Sport-Related Concussion and Sensory Function in Young Adults

Context:

The long-term implications of concussive injuries for brain and cognitive health represent a growing concern in the public consciousness. As such, identifying measures sensitive to the subtle yet persistent effects of concussive injuries is warranted.

Objective:

To investigate how concussion sustained early in life influences visual processing in young adults. We predicted that young adults with a history of concussion would show decreased sensory processing, as noted by a reduction in P1 event-related potential component amplitude.

Design:

Cross-sectional study.

Setting:

Research laboratory.

Patients or Other Participants:

Thirty-six adults (18 with a history of concussion, 18 controls) between the ages of 20 and 28 years completed a pattern-reversal visual evoked potential task while event-related potentials were recorded.

Main Outcome Measure(s):

The groups did not differ in any demographic variables (all P values > .05), yet those with a concussive history exhibited reduced P1 amplitude compared with the control participants (P = .05).

Conclusions:

These results suggest that concussion history has a negative effect on visual processing in young adults. Further, upper-level neurocognitive deficits associated with concussion may, in part, result from less efficient downstream sensory capture.Key Words: mild traumatic brain injuries, visual processing, event-related potentials, pattern-reversal visual evoked potentials

Key Points

• Visual processing and higher-level cognitive function were affected by concussion over the long term.
• The potential contributions of low-level sensory deficits to higher-order neurocognitive dysfunction after concussion should be studied.
• Event-related potentials have greater sensitivity than standard clinical tools and have the potential for clinical use.

The long-term and cumulative effects of concussive injuries represent a growing concern in the public consciousness. Concussion has been defined as “a complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces.”^1,2 Estimated incidence rates for this condition, described as a “silent epidemic” by the Centers for Disease Control and Prevention,^2–5 range from a conservative 300 000 per year^4–6 to a more liberal and recent estimate of 3.8 million cases in the United States annually.⁷ Because 15% to 20% of these injuries result from sport participation,⁸ sport-related concussion represents an increasing concern, not only in the public domain but also in clinical and research settings.Based on clinical evaluations, concussed persons typically return to their preinjury level of functioning within 7 to 10 days of injury,^9,10 a time paralleling the acute neurometabolic cascade associated with concussion.^11,12 Indeed, several investigations^2,13–15 of young adult athletes with a concussion history indicate normal performance on a variety of clinical tests after the acute injury stage. However, more recent studies using highly sensitive assessment measures suggest that a multitude of chronic nervous system dysfunctions and cognitive deficits stem from concussive injuries.^16–28 Thus, the chronic, subclinical effects of concussion remain unclear, and measures sensitive to subtle and persistent deficits stemming from concussion are needed.Electroencephalography, which records brain activity from electrodes placed on the scalp, has been extensively used to examine neuroelectric activity in normal and clinical populations for almost a century. More recently, event-related potentials (ERPs; patterns of neuroelectric activity that occur in preparation for or in response to an event) have emerged as a technique to provide insight into the neural processes underlying perception, memory, and action.²⁹ The ERPs may be obligatory responses (exogenous) to stimuli in the environment or may reflect higher-order cognitive processes (endogenous) that often require active consideration by a person.³⁰Over the past decade, electroencephalography and ERPs in particular have demonstrated the requisite sensitivity to detect subtle, covert deficits in neurocognitive function associated with concussion^{17,23,27,31–33} (for review, see Broglio et al²⁹). Although several groups have evaluated ERP components, such as the ERN, N2, and P3, to examine attention, perception, and memory, few authors^23,34–36 have evaluated the effects of concussion on neuroelectric indexes of sensory function. In particular, only 3 studies have evaluated the influence of concussion on visual-evoked potentials (VEPs).^23,34,35 Findings from these studies suggest that for a significant portion of people, concussion may lead to chronic impairment in the neuroelectric correlates of visual processing.Believed to reflect the functional integrity of the visual system, VEPs are electrophysiologic signals passively evoked in response to visual stimuli that demonstrate a parietal-occipital maximum.^37–40 Efficient visual processing and sensory integration are essential to day-to-day functioning^34,41; however, the visual system of a concussed individual is typically unevaluated.³⁴ Thus, VEPs represent an underused and potentially valuable tool for evaluating and understanding sensory and nervous system dysfunction after injury.One VEP paradigm of particular utility is the pattern-reversal task (PR-VEP). This task uses an inverting patterned stimulus to evoke an electrocortical waveform, which is characterized by a negative deflection at about 75 milliseconds (N75), followed by a positive deflection at about 100 milliseconds (P1).⁴² The PR-VEP task is a standard in clinical research assessing central nervous system function⁴³ because of the high sensitivity, specificity, and intraindividual stability of PR-VEPs relative to VEPs elicited by other paradigms.^44,45 Specifically, the P1 elicited by this paradigm is less variable than the P1 components elicited by other paradigms, making it preferable for evaluating clinical populations.⁴⁰ For example, Sarnthein et al⁴⁵ observed a test-retest sensitivity of 95% and specificity of 99.7% for P1 component values. Further, Mellow et al,⁴⁶ evaluating binocular reproducibility in a single participant, observed test-retest coefficients of variation of 9% to 14% for P1 amplitude and 1% to 2% for P1 latency.The P1 component is an exogenous or obligatory potential and is the first positive-going deflection after stimulus presentation (or inversion). The P1 is thought to reflect sensory processes such as gating, amplification, and preferential attention to sensory inputs.^38,47 Within the context of the PR-VEP paradigm, the P1 is believed to index the functioning of the geniculostriatal pathway,³⁹ which is thought to mediate visual processing. The P1 component values can provide important information to researchers and clinicians: reduced P1 amplitude may indicate neuronal atrophy,⁴⁸ and increased P1 latency may indicate slowed neural conduction within the visual pathways.⁴⁹To our knowledge, only one set of authors²³ has evaluated the P1 component in relation to sport-induced concussion by using a pattern-reversal task to elicit VEPs in young and middle-aged adults. Approximately one-third of the participants who reported a concussion history evidenced P1 deficits, as determined by clinical diagnostic criteria. Such findings suggest that concussion may negatively influence the P1 component in a subset of persons, but further investigation is warranted to clarify the nature of the relationship between concussive injuries and the P1 VEP. Accordingly, the purpose of our investigation was to assess the relationship of sport-related concussion on visual processing using a pattern-reversal paradigm.     

Ankle Dorsiflexion Among Healthy Men With Different Qualities of Lower Extremity Movement

Context:

Lower extremity movement patterns have been implicated as a risk factor for various knee disorders. Ankle-dorsiflexion (DF) range of motion (ROM) has previously been associated with a faulty movement pattern among healthy female participants.

Objective:

To determine the association between ankle DF ROM and the quality of lower extremity movement during the lateral step-down test among healthy male participants.

Design:

Cross-sectional study.

Setting:

Training facility of the Israel Defense Forces.

Patients or Other Participants:

Fifty-five healthy male Israeli military recruits (age = 19.7 ± 1.1 years, height = 175.4 ± 6.4 cm, mass = 72.0 ± 7.6 kg).

Intervention(s):

Dorsiflexion ROM was measured in weight-bearing and non–weight-bearing conditions using a fluid-filled inclinometer and a universal goniometer, respectively. Lower extremity movement pattern was assessed visually using the lateral step-down test and classified categorically as good or moderate. All measurements were performed bilaterally.

Main Outcome Measure(s):

Weight-bearing and non–weight-bearing DF ROM were more limited among participants with moderate quality of movement than in those with good quality of movement on the dominant side (P = .01 and P = .02 for weight-bearing and non–weight-bearing DF, respectively). Non–weight-bearing DF demonstrated a trend toward a decreased range among participants with moderate compared with participants with good quality of movement on the nondominant side (P = .03 [adjusted P = .025]). Weight-bearing DF was not different between participants with good and moderate movement patterns on the nondominant side (P = .10). Weight-bearing and non–weight-bearing ankle DF ROM correlated significantly with the quality of movement on both sides (P < .01 and P < .05 on the dominant and nondominant side, respectively).

Conclusions:

Ankle DF ROM was associated with quality of movement among healthy male participants. The association seemed weaker in males than in females.Key Words: anterior cruciate ligament, hip, knee, lateral step-down test, patellofemoral pain syndrome

Key Points

• Healthy males with a moderate quality of movement on the lateral step-down test exhibited less ankle-dorsiflexion range of motion than those with a good quality of movement.
• When a lower quality of movement is present in males, clinicians should consider interventions to increase ankle dorsiflexion.

An altered lower extremity movement pattern, consisting of excessive femoral adduction and internal rotation leading to excessive knee valgus alignment, has been implicated as a risk factor for patellofemoral pain syndrome (PFPS) and noncontact anterior cruciate ligament injuries.^1–3 Various factors have been suggested to contribute to an altered movement pattern, including decreased strength of the ipsilateral hip musculature,^4,5 increased subtalar joint pronation,^6,7 and altered motor control.⁸ Assessment of movement pattern and the factors associated with it is therefore commonly performed in the evaluation of patients with PFPS, as well as in screening for the risk of knee injury.^9–11Another possible contributor to an altered movement pattern is the available ipsilateral ankle-dorsiflexion (DF) range of motion (ROM). Decreased ankle DF ROM can limit the forward progression of the tibia over the talus during activities that require simultaneous knee flexion and ankle DF (eg, squatting, stair descent). A possible compensation for the limited motion of the tibia could be subtalar pronation, which may shift the tibia and the knee medially into greater valgus alignment.^6,12–14 Some evidence already exists for the association between ankle DF and the lower extremity movement pattern. Decreased DF has been previously associated with increased knee valgus during a drop-land maneuver,¹⁴ a squat,¹⁵ and a step-down maneuver¹⁶ among healthy participants.One limitation of the current literature regarding this topic is the inclusion of only female participants in many of the studies evaluating lower extremity movement patterns and the associated factors.^{4,6,14,16–18} This is likely because of sex differences in kinematics, kinetics, and muscle-activation patterns during various functional activities.^8,19,20 Women have been shown to perform activities such as cutting, jumping, and landing with greater knee valgus alignment and greater knee extension than men.^19,20 These differences are hypothesized to account for the greater incidence of noncontact anterior cruciate ligament tears and PFPS among women.^1,2,21,22 Accordingly, authors^14,16 of the 2 studies that have previously linked decreased ankle DF with a faulty movement pattern included only female participants as well. A third study of a mixed population demonstrated only a statistical trend for the association between ankle DF and a faulty movement pattern.¹⁵ It is therefore unclear whether the association between ankle DF and lower extremity movement pattern is similar for both sexes.Paradoxically, another limitation of the current literature is the use of sophisticated 3-D motion-analysis systems in many of the studies evaluating lower extremity movement patterns.^2,4,14,17,18 Although this type of analysis certainly contributes to a high level of precision and reliability, clinicians and coaches typically do not have the access, time, or skill to operate such systems. Instead, visual observation is often relied on to assess movement patterns in the clinic or on the field. It is unknown, however, to what extent any movement deviations identified during 3-D motion analyses correlate with movement deviations identified visually. Consequently, the findings from 3-D motion analyses studies may be difficult to apply in the clinical setting or on the field. We therefore decided to assess whether ankle DF ROM is related to the quality of lower extremity movement as assessed visually among healthy male participants.The lateral step-down (LSD) test is frequently used to assess movement patterns of the lower extremity.^9,11,23–25 Piva et al²⁵ suggested a visually based rating system for classifying the quality of movement during the LSD test. The reliability of this rating system has been established previously.^16,25 Our hypothesis was that male participants with a lower quality of movement on the LSD would exhibit less ankle DF ROM.     

Unusual Mechanism of Injury Resulting in a Thoracic Chance Fracture in a Rodeo Athlete: A Case Report

Objective:

To introduce the characteristics of a Chance fracture and increase awareness of the mechanism of injury that may occur during athletic activity.

Background:

A T12 Chance fracture was diagnosed in an 18-year-old male rodeo athlete. The rider was forced into extreme lumbothoracic hyperflexion when the horse bucked within the chute, pinning the rider''s legs to his chest.

Differential Diagnosis:

Burst fracture, abdominal organ rupture, spinal dislocation, spinal cord injury, disk herniation, pars interarticularis fracture, spinal nerve injury, paralysis.

Treatment:

The patient underwent an open reduction and fixation of the thoracic fracture. Posterior stabilization was obtained with nonsegmental instrumentation. Allograft and autografts were used for posterolateral arthrodesis at T11–T12 and T12–L1.

Uniqueness:

Motor vehicle crashes with occupants wearing lap-type–only restraints account for nearly all previously reported Chance fractures. When only lap seatbelts are worn, the pelvis is stabilized, and the torso continues moving forward with impact. The stabilized body segment for this individual was reversed. Nearly 3 years after the initial surgery, fixation, and infection, the bareback rider has returned to full participation in rodeo.

Conclusions:

To our knowledge, this is the first reported diagnosis of a T12 Chance fracture in a rodeo athlete. When animals buck, athletes can be forced into hyperflexion, exposing them to Chance fractures. Therefore, anyone treating rodeo athletes must suspect possible spinal fracture when this mechanism is present and must treat all athletes with early conservative management and hospital referral.Key Words: sports, flexion-distraction injuries, spinal fractures, emergency medicineRodeo is considered an extreme sport, and subsequently, extreme risk is implied.¹ Horseback riding, including rodeo and recreational riding, has been identified as one of the most common activities resulting in injuries requiring visits to emergency departments.² The rough-stock events in rodeo include bareback riding, saddle bronc riding, and bull riding.¹ Other events, including steer wrestling, tie-down roping, team roping, and ladies'' barrel racing, are considered timed events.¹ In rodeo events, participants most often are injured while participating in rough-stock events.³ In an epidemiologic analysis of Canadian Professional Rodeo athletes, Butterwick et al⁴ found bull riders (31.2% of all injuries) were injured most frequently, followed by bareback riders and saddle bronc riders (16.0% and 14%, respectively, of all injuries).Intercollegiate rodeo is extremely competitive; the skill required and risk of injury are comparable with those seen in the professional ranks.⁵ During a 7-month, 10-event rodeo season, nearly one-quarter of all collegiate rough stock competitors sustained injuries.⁵ At the professional and collegiate ranks, competitors enter multiple rodeos each week and travel among towns to attend competitions. Depending on the event, the injury rate for rodeo participants ranges from 2.3 to 19.7 per 100 animal-exposures.^5,6 Rough-stock competitors are 3 to 4 times more likely to be injured than other rodeo competitors.^6,7Young athletes have an increased frequency of thoracolumbar spine injuries while participating in high-risk sporting activities, such as elite skiing, climbing, motorcycle racing, skydiving, and other extreme sports.⁸ More than half (53%) of all trauma to the thoracic and lumbar spine seen in adolescents has been attributed to recreational or competitive athletic activities.⁹ Chance¹⁰ first described unusual spinal injury patterns with a hyperflexion mechanism, usually resulting in a splitting of the posterior lumbar spine and neural arch without spinal cord damage, in patients admitted to the hospital after automobile crashes. Denis¹¹ later postulated that the use of lap seatbelts in automobiles could explain these injuries because the restraints serve as an axis of rotation, subjecting the anterior spinal elements to compression during flexion and the posterior elements to distraction or tension.A Chance fracture is a unique spinal hyperflexion-distraction injury occurring around a fulcrum, which most often is described in the literature as a seatbelt crossing the lap.¹² Ruptures are seen in the posterior ligaments, and the injury may include fractures to the pedicles or spinous process of the vertebrae.¹⁰ Chance fractures are relatively uncommon among the general population with the exception of individuals injured in automobile accidents and high-velocity athletic activities.^13,14Denis¹¹ proposed classifying the spine into 3 columns. The anterior column comprises the anterior longitudinal ligament, anterior annulus, and anterior vertebral body.¹¹ The middle column comprises the posterior longitudinal ligament, posterior annulus, and posterior portion of the vertebral body. The posterior column comprises the spinal structures located dorsally to the posterior longitudinal ligament.¹¹ Chance fractures result in a failure of the bony or soft tissue structures of the posterior and middle columns as they are subjected to tension, whereas the anterior column remains largely intact and becomes a fulcrum for injury.¹¹ We present this case of a collegiate bareback rider who sustained a Chance fracture of the thoracic vertebra (T12). The mechanism of injury was the same as for other reported Chance fractures; however, the thoracic spine was stabilized in this patient, whereas most researchers have indicated the legs are typically the fixated segment during injury.^{10–12,14,15} The athlete successfully underwent surgery; although he had medical complications, he eventually returned to bareback riding competition.     

Jump-Landing Biomechanics and Knee-Laxity Change Across the Menstrual Cycle in Women With Anterior Cruciate Ligament Reconstruction

Context:

Of the individuals able to return to sport participation after an anterior cruciate ligament(ACL) injury, up to 25% will experience a second ACL injury. This population may be more sensitive to hormonal fluctuations, which may explain this high rate of second injury.

Objective:

To examine changes in 3-dimensional hip and knee kinematics and kinetics during a jump landing and to examine knee laxity across the menstrual cycle in women with histories of unilateral noncontact ACL injury.

Design

 Controlled laboratory study.

Setting:

Laboratory.

Patients or Other Participants:

A total of 20 women (age = 19.6 ± 1.3 years, height = 168.6 ± 5.3 cm, mass = 66.2 ± 9.1 kg) with unilateral, noncontact ACL injuries.

Intervention(s)

Participants completed a jump-landing task and knee-laxity assessment 3 to 5 days after the onset of menses and within 3 days of a positive ovulation test.

Main Outcome Measure(s):

Kinematics in the uninjured limb at initial contact with the ground during a jump landing, peak kinematics and kinetics during the loading phase of landing, anterior knee laxity via the KT-1000, peak vertical ground reaction force, and blood hormone concentrations (estradiol-β-17, progesterone, free testosterone).

Results:

At ovulation, estradiol-β-17 (t = −2.9, P = .009), progesterone (t = −3.4, P = .003), and anterior knee laxity (t = −2.3, P = .03) increased, and participants presented with greater knee-valgus moment (Z = −2.6, P = .01) and femoral internal rotation (t = −2.1, P = .047). However, during the menses test session, participants landed harder (greater peak vertical ground reaction force; t = 2.2, P = .04), with the tibia internally rotated at initial contact (t = 2.8, P = .01) and greater hip internal-rotation moment (Z = −2.4, P = .02). No other changes were observed across the menstrual cycle.

Conclusions

Knee and hip mechanics in both phases of the menstrual cycle represented a greater potential risk of ACL loading. Observed changes in landing mechanics may explain why the risk of second ACL injury is elevated in this population.Key Words: hormones, estrogen, vertical ground reaction force, knee-valgus moment

Key Points

• Clinicians should be aware of the high rate of second injury and biomechanical consequences of many factors related to return to sport participation after anterior cruciate ligament (ACL) injury, including sensitivity to hormonal fluctuations and asymmetrical limb loading.
• The biomechanical profiles of women with ACL injury changed during the preovulatory phase of the menstrual cycle, possibly increasing the risk of second ACL injury.
• Women with ACL reconstructions should have their landing mechanics evaluated before returning to sport participation.
• Anterior knee laxity and jump-landing biomechanics changed across the menstrual cycle in women with unilateral ACL injuries.
• Both menstrual cycle phases had biomechanical variables associated with ACL loading.

The risk of sustaining a noncontact anterior cruciate ligament (ACL) injury is not equal across the menstrual cycle.^1–4 The menstrual cycle consists of the follicular, ovulatory, and luteal phases, which have markedly different hormonal profiles. The follicular phase is associated with the lowest concentrations of estrogen, progesterone, and testosterone. Ovulation, which follows the follicular phase, occurs between days 9 and 20 and is associated with a spike in luteinizing hormone and then a spike in estrogen.⁵ This is the largest concentration of estrogen during the menstrual cycle. The final phase of the menstrual cycle is the luteal phase, which is associated with prolonged elevated estrogen levels. Progesterone also increases substantially during this phase. Researchers^6,7 have reached consensus that the preovulatory phase (from the follicular phase to ovulation) of the menstrual cycle presents the highest risk for noncontact ACL injuries. The risk of injury is thought to result from hormonal fluctuations influencing tissue that, in turn, affects neuromuscular characteristics during dynamic tasks, such as landing from a jump.^8,9 Differences across menstrual cycle phases have been identified in variables believed to be associated with joint stability, including laxity,^5,10,11 muscle stiffness,⁹ strength,^12–14 proprioception,¹⁵ and muscle-activation patterns.¹⁶ However, this area is not without controversy, with other researchers^17–20 observing no change across the menstrual cycle in similar variables.Reproductive hormones seem to influence ACL laxity in females with normal menstrual cycles and physiologic levels of estrogen and progesterone.^5,11,21–25 Numerous authors have concluded that anterior laxity differs between sexes, with males having less laxity than females.^25–31 Again, this area is not without controversy, as several authors have concluded that anterior knee laxity does not change across the menstrual cycle.^18,31–36 However, negative correlations have been observed between ACL stiffness and estrogen concentration in active females, indicating that an increase in estrogen is associated with lower levels of ligament stiffness.²¹ Additionally, evidence^8,37,38 has suggested that ACL laxity may influence muscular response during dynamic activity. Park et al⁸ collected biomechanical data on 26 participants and initially observed no change in kinematic and kinetic variables across the 3 phases of the menstrual cycle. However, when they reorganized participants based on their relative levels of knee laxity into low-, medium-, and high-laxity time points, the authors found that the high-laxity group had a 30% increase in adduction impulse, 20% increase in adduction moment, and 45% increase in external rotation compared with the medium- and low-laxity groups.⁸ This information demonstrates that knee laxity can influence joint loading and potentially influence noncontact ACL injury.Besides knee laxity, other biomechanical factors are associated with ACL loading and ACL injury during jumping and landing. Landing with decreased sagittal-plane motion or moment (knee and hip extension) and increased frontal- and rotational-plane motion of the hip (adduction and internal rotation) and knee (valgus and internal rotation) contribute to ACL loading.³⁹ Researchers^8,40,41 have examined changes in jump-landing mechanics across the menstrual cycle in healthy female populations without histories of ACL injury. These authors observed no change in jump-landing hip and knee mechanics across the menstrual cycle, leading them to conclude that injury rates were most likely due to other factors, including strength or ligament properties.⁴¹ One limitation of these studies is that some women may be more responsive to hormonal fluctuations than others (ie, responders versus nonresponders).^5,11 We theorize that females with histories of ACL injury may be responsive to hormonal fluctuations, and this increased sensitivity may have a greater effect on tissue and ultimately landing mechanics. Additionally, up to 25% of individuals who sustain primary ACL ruptures will have second ACL injuries, with many second injuries occurring in the contralateral limb.^42–44 In a recent paper on second ACL injuries, Paterno et al⁴² examined athletes who were returning to high-level sports and observed that 75% of second ACL injuries occurred in the contralateral limb and 88% of individuals sustaining these injuries were females. The rate of second injury is particularly high for individuals returning to sport participation even after successfully completing rehabilitation programs.⁴⁴ This warrants further investigation because underlying risk factors, such as hormones, could play a role in the rates of second injury in the contralateral limb. Therefore, the purpose of our study was to examine anterior knee laxity and 3-dimensional hip and knee kinematics and kinetics across the menstrual cycle in a population of women with previous unilateral, noncontact ACL injuries. We hypothesized that biomechanical variables assessed during a jump landing would be altered at ovulation in ways that would increase ACL loading and laxity compared with menses. We based this theory on research in which investigators^5,38 have identified increased ligamentous laxity at ovulation. Additionally, we hypothesized that hip and knee kinematics and kinetics during a jump landing would change in ways associated with increased ACL loading.^5,38     

Validity of Musculoskeletal Ultrasound for Identification of Humeroradial Joint Chondral Lesions: A Preliminary Investigation

Context:

Epicondylalgia is a common condition involving pain-generating structures such as tendon, neural, and chondral tissue. The current noninvasive reference standard for identifying chondral lesions is magnetic resonance imaging. Musculoskeletal ultrasound (MUS) may be an inexpensive and effective alternative.

Objective:

To determine the intrarater reliability and validity of MUS for identifying humeroradial joint (HRJ) chondral lesions.

Design:

Cross-sectional study.

Setting:

Clinical anatomy research laboratory.

Patients or Other Participants:

Twenty-eight embalmed cadavers (14 women, 14 men; mean age = 79.5 ± 8.5 years).

Main Outcome Measure(s):

An athletic trainer performed MUS evaluation of each anterior and distal-posterior capitellum and radial head to identify chondral lesions. The reference standard was identification of chondral lesions by gross macroscopic examination. Intrarater reliability for reproducing an image was calculated using the intraclass correlation coefficient (3,k) for measurements of the articular surface using 2 images. Intrarater reliability to evaluate a single image was calculated using the Cohen κ for agreement as to the presence of chondral lesions. Validity was calculated using the agreement of MUS images and gross macroscopic examination.

Results:

Intrarater reliability was 0.88 (95% confidence interval = 0.77, 0.94) for reproducing an image and 0.93 (95% confidence interval = 0.80, 1.06) for evaluating a single image. Identifying chondral lesions on all HRJ surfaces with MUS demonstrated sensitivity = 0.93, specificity = 0.28, positive predictive value = 0.58, negative predictive value = 0.77, positive likelihood ratio = 1.28, and negative likelihood ratio = 0.27.

Conclusions:

Musculoskeletal ultrasound is a reliable and sensitive tool for a clinician with relatively little experience and training to rule out HRJ chondral lesions. These results may assist with clinical assessment and decision making in patients with lateral epicondylalgia to rule out HRJ chondral lesions.Key Words: elbow joint, articular cartilage, reliability, assessment

Key Points

• When used by a clinician with limited experience and training, musculoskeletal ultrasound imaging was reliable and sensitive for ruling out humeroradial joint chondral lesions.
• More study is needed, but musculoskeletal ultrasound imaging may be helpful in assessing and managing patients with lateral epicondylalgia.

The elbow is one of the joints most commonly affected by articular cartilage degeneration and loosening of chondral fragments.¹ Chondral lesions and articular cartilage degeneration primarily occur in the lateral compartment of the elbow within the humeroradial joint (HRJ).^2–4 Although HRJ chondral lesions can occur secondary to acute trauma, they may be present in the absence of trauma.⁵Lateral elbow conditions occur in a variety of sports,⁶ and up to 50% of overhead athletes experience elbow injuries.⁷ In overhead athletes, valgus extension overload is observed during the late cocking phase of throwing.⁸ This results in significant compression forces of up to 500 N on the HRJ, which can lead to chondral lesions.^8,9 In the general population, HRJ chondral lesions have been demonstrated in 51% to 81% of patients with chronic lateral elbow pain.^5,10 Articular cartilage lesions are easily misdiagnosed as tendinopathy of the wrist extensors because they have similar clinical presentations.^5,11 Symptoms include insidious onset of lateral elbow pain, pain with resisted wrist extension, and failure to respond to conservative treatment.⁵ To our knowledge, no validated clinical examination exists for the differential diagnosis of HRJ chondral lesions from lateral epicondylopathy.The current noninvasive reference standard for the diagnosis of chondral lesions is magnetic resonance imaging.¹² Musculoskeletal ultrasound (MUS) is a safe and inexpensive alternative imaging technique that is effective in showing articular cartilage abnormalities and loose bodies,^1,13 although most research to date has focused on the hip, knee, and hand.^12,14,15 At the elbow joint, several authors^16,17 have demonstrated validity for detecting loose bodies with MUS. However, we know of no authors who have evaluated the validity of MUS for identifying HRJ chondral lesions.Traditionally, radiologists perform and interpret MUS examinations.¹⁸ More recently, the use of MUS has expanded to sports medicine clinicians, physiotherapists, and athletic trainers.^18–21 As the use of MUS extends into clinics and athletic training facilities, the reliability of clinicians'' examinations with MUS must be expanded because the technique is user dependent.²² Furthermore, it is critical to establish whether the performance of such clinicians is equal to that of expert technicians. However, before interrater reliability can be evaluated, MUS must be validated for identifying HRJ chondral lesions to determine its usefulness.Although our purpose was not to establish the reliability of clinicians'' use of MUS, we know that for a tool to be valid, it must be reliable.²³ Therefore, the purposes of our study were to (1) investigate the intrarater reliability and validity of an athletic trainer to identify chondral lesions in the HRJ using MUS and (2) determine the prevalence of HRJ chondral lesions in elderly specimens. We hypothesized that an athletic trainer would be reliable at reproducing and evaluating MUS images and accurate in identifying chondral lesions at the HRJ using MUS.     

Feedback in Clinical Education,Part I: Characteristics of Feedback Provided by Approved Clinical Instructors

Context

Providing students with feedback is an important component of athletic training clinical education; however, little information is known about the feedback that Approved Clinical Instructors (ACIs; now known as preceptors) currently provide to athletic training students (ATSs).

Objective

To characterize the feedback provided by ACIs to ATSs during clinical education experiences.

Design

Qualitative study.

Setting

One National Collegiate Athletic Association Division I athletic training facility and 1 outpatient rehabilitation clinic that were clinical sites for 1 entry-level master''s degree program accredited by the Commission on Accreditation of Athletic Training Education.

Patients or Other Participants

A total of 4 ACIs with various experience levels and 4 second-year ATSs.

Data Collection and Analysis

Extensive field observations were audio recorded, transcribed, and integrated with field notes for analysis. The constant comparative approach of open, axial, and selective coding was used to inductively analyze data and develop codes and categories. Member checking, triangulation, and peer debriefing were used to promote trustworthiness of the study.

Results

The ACIs gave 88 feedback statements in 45 hours and 10 minutes of observation. Characteristics of feedback categories included purpose, timing, specificity, content, form, and privacy.

Conclusions

Feedback that ACIs provided included several components that made each feedback exchange unique. The ACIs in our study provided feedback that is supported by the literature, suggesting that ACIs are using current recommendations for providing feedback. Feedback needs to be investigated across multiple athletic training education programs to gain more understanding of certain areas of feedback, including frequency, privacy, and form.Key Words: assessment, evaluation, pedagogy, preceptors

Key Points

• Feedback had several different components that made each feedback exchange unique.
• The feedback that the Approved Clinical Instructors (ACIs) provided mostly was aligned with recommendations in the literature, suggesting our ACIs provided effective feedback to athletic training students and current recommendations are applicable to athletic training clinical education.
• Researchers should continue to assess the feedback that is occurring in different athletic training education programs to gain more understanding of the current use of feedback across several programs so they can guide ACI training and evaluation, including the development of recommendations for the appropriate frequency of feedback.

Feedback is any information provided to a student that helps correct, reinforce, or suggest change in his or her performance.^1,2 It is a type of evaluation that is less formal and judgmental than structured, summative evaluation and assessment² and is an effective educational technique.^3,4 Providing feedback to students also has been described as one of the most important characteristics of clinical instructors in athletic training,^5,6 medicine,^7,8 nursing,⁹ and physical therapy.¹⁰ In addition, feedback has been shown to improve clinical performance in medical^11,12 and nursing students.^13,14Most research on feedback has been focused on the recommended characteristics of feedback, such as its specificity, timing, tone, and relation to educational and career goals.^3,4,15 Much of the existing research is based on student and instructor perceptions of whether these recommendations are followed rather than actual observed feedback.^12,16 Feedback research in athletic training is much less extensive than other areas of clinical education. Most research on feedback in athletic training education has been focused on general effective clinical instructor behaviors.^5,17,18 These investigators have identified feedback as an important behavior of Approved Clinical Instructors (ACIs),⁵ and along with evaluation, it is considered a standard for selecting, training, and evaluating ACIs.^17,18 Several authors^1,19,20 have provided suggestions for giving effective feedback to athletic training students (ATSs) in clinical education. The supervision, questioning, feedback (SQF) model of clinical teaching provides guidelines for giving feedback to ATSs at different developmental levels.¹ Stemmans²¹ compared the quantity of feedback provided by clinical instructors with different amounts of experience. The researcher found that novice clinical instructors provided less feedback to ATSs than more experienced clinical instructors did. Berry et al²² reported that students in outpatient rehabilitation clinics spent more time engaged in active learning than did students in intercollegiate and high school settings. Because learning experiences differ among clinical settings, the feedback exchange also may differ among settings.Providing feedback is considered to be one of the most important roles of ACIs during clinical education experiences.^5,6 However, feedback has been minimally explored in practitioner-based articles and research studies specific to athletic training. Little is known about the feedback ACIs provide to ATSs. Similarly, to our knowledge, no one has examined how feedback is used in different clinical education settings, such as rehabilitation clinics and collegiate athletic training facilities. Therefore, the purpose of our study was to characterize the feedback provided by ACIs to ATSs during clinical education sessions in 1 outpatient rehabilitation clinic and 1 collegiate athletic training facility.     

Medial Tibiofemoral-Joint Stiffness in Males and Females Across the Lifespan

Context:

Analyzing ligament stiffness between males and females at 3 maturational stages across the lifespan may provide insight into whether changes in ligament behavior with aging may contribute to joint laxity.

Objective:

To compare the stiffness of the medial structures of the tibiofemoral joint and the medial collateral ligament to determine if there are differences at 3 distinct ages and between the sexes.

Design:

Cross-sectional study.

Setting:

Laboratory.

Patients or Other Participants:

A total of 108 healthy and physically active volunteers with no previous knee surgery, no acute knee injury, and no use of exogenous hormones in the past 6 months participated. They were divided into 6 groups based on sex and age (8–10, 18–40, 50–75 years).

Main Outcome Measure(s):

Ligament stiffness of the tibiofemoral joint was measured with an arthrometer in 0° and 20° of tibiofemoral-joint flexion. The slope values of the force-strain line that represents stiffness of the medial tibiofemoral joint at 0° and the medial collateral ligament at 20° of flexion were obtained.

Results:

When height and mass were controlled, we found a main effect (P < .001) for age group: the 8- to 10-year olds were less stiff than both the 18- to 40- and the 50- to 75-year-old groups. No effects of sex or tibiofemoral-joint position on stiffness measures were noted when height and mass were included as covariates.

Conclusions:

Prepubescent medial tibiofemoral-joint stiffness was less than postpubescent knee stiffness. Medial tibiofemoral-joint stiffness was related to height and mass after puberty in men and women.Key Words: medial collateral ligament, arthrometry, hormones, sex differences

Key Points

• Medial tibiofemoral-joint stiffness was less in prepubescents than in postpubescents.
• After puberty, medial tibiofemoral-joint stiffness was influenced by height and mass in both men and women.

The mechanical properties of connective tissue with respect to sex have been studied mainly in an effort to explain the greater risk of knee ligament injury in female athletes than in male athletes. Most authors^1–3 have focused on the laxity of the anterior cruciate ligament (ACL) in postpubertal men and women. Theories have been generated and extensive research has been conducted to explain the two- to eightfold increase in ACL injuries in female athletes over male athletes.^1–4 Although a single cause has not been identified, risk factors have been generalized into 4 categories⁵: environmental (external factors such as surface and footwear),⁵ anatomic and postural,^1–4 hormonal,^6–13 and biomechanical^14–16 (such as kinematics^16,17 and neuromuscular factors^15,18,19).The injury rate to the collateral ligaments of the knee is also greater in females than males but not to the same extent as for ACL injury.^1,2 However, the medial collateral ligament (MCL), a major stabilizing structure in the tibiofemoral joint, remains a prevalent source of injury in the general population,²⁰ particularly as a result of sport participation.^1–3 As males and females mature from prepuberty, through puberty and adulthood, and then reach the postfertile years, the material properties and structure of the joints change, as do hormonal levels.^21–23 In this study, we examine the mechanical and material properties of the MCL and other supporting structures of the tibiofemoral joint in vivo in prepubertal and postpubertal males and females and older adults, including postmenopausal females. These properties in these groups of participants have not been previously described in the literature. Examining the material properties of a ligament, such as stiffness, provides a way to detect joint structural differences between sexes and across age groups, thus elucidating structural differences in the ligament material properties secondary to the exposure to sex hormones.Aronson et al^24,25 measured stiffness of the medial tibiofemoral joint in full extension because of the important role the medial joint structures play in minimizing valgus positioning (abduction of the joint), which has been suggested to contribute to ACL injury risk.^3,5,15–17 Additionally, Aronson et al^24,25 examined the extracapsular MCL in 20° of flexion to reduce the confounding contributions of possible changes in intracapsular structures, such as meniscal injury and articular degeneration, to stiffness measurements.The purpose of our investigation was to assess the stiffness of the medial tibiofemoral joint in full extension and the MCL in 20° of flexion in males and females in 3 distinct age groups (prepubertal children, postpubertal young adults, and older adults).     

Soccer-Specific Warm-Up and Lower Extremity Injury Rates in Collegiate Male Soccer Players

Context:

A number of comprehensive injury-prevention programs have demonstrated injury risk-reduction effects but have had limited adoption across athletic settings. This may be due to program noncompliance, minimal exercise supervision, lack of exercise progression, and sport specificity. A soccer-specific program described as the F-MARC 11+ was developed by an expert group in association with the Federation Internationale de Football Association (FIFA) Medical Assessment and Research Centre (F-MARC) to require minimal equipment and implementation as part of regular soccer training. The F-MARC 11+ has been shown to reduce injury risk in youth female soccer players but has not been evaluated in an American male collegiate population.

Objective:

To investigate the effects of a soccer-specific warm-up program (F-MARC 11+) on lower extremity injury incidence in male collegiate soccer players.

Design:

Cohort study.

Setting:

One American collegiate soccer team followed for 2 seasons.

Patients or Other Participants:

Forty-one male collegiate athletes aged 18–25 years.

Intervention(s):

The F-MARC 11+ program is a comprehensive warm-up program targeting muscular strength, body kinesthetic awareness, and neuromuscular control during static and dynamic movements. Training sessions and program progression were monitored by a certified athletic trainer.

Main Outcome Measure(s):

Lower extremity injury risk and time lost to lower extremity injury.

Results:

The injury rate in the referent season was 8.1 injuries per 1000 exposures with 291 days lost and 2.2 injuries per 1000 exposures and 52 days lost in the intervention season. The intervention season had reductions in the relative risk (RR) of lower extremity injury of 72% (RR = 0.28, 95% confidence interval = 0.09, 0.85) and time lost to lower extremity injury (P < .01).

Conclusions:

This F-MARC 11+ program reduced overall risk and severity of lower extremity injury compared with controls in collegiate-aged male soccer athletes.Key Words: injury prevention, sport injuries, athletic trainers

Key Points

• The F-MARC 11+ reduced the risk of lower extremity injuries in youth female soccer players, but limited evidence for its effectiveness exists in males and at the collegiate level.
• A traditional warm-up did not prevent injury as effectively as the F-MARC 11+ program, despite taking the same amount of time.
• When supervised by an athletic trainer, the F-MARC 11+ prevented injuries in collegiate male soccer players.
• An athletic trainer administered intervention, reduced injury risk, and improved program compliance, progression, and execution.

Soccer is among the most popular sports in the world, boasting more than 265 million¹ youth and amateur players and more than 37 000 American collegiate players.² Soccer participation has continued to increase over the past decade worldwide and especially in the United States National Collegiate Athletic Association (NCAA).² Lower extremity injury rates for male NCAA soccer athletes have remained relativity stable over the past decade (practice versus game: 8 versus 12.18 per 1000 exposures).² Junge and Dvorak,³ in a systematic review of soccer injuries in international male players, reported 10 to 35 injuries per 1000 hours of match play and 2 to 7 per 1000 hours of training in international male soccer players. In cohorts of international, elite-level soccer athletes, the injury rate was high (1.3 injuries per player per season); most injuries affected the lower extremity (87%) and resulted from noncontact mechanisms (58%).⁴ The most common injury in male collegiate soccer players was ankle sprains (3.19 per 1000 exposures), followed by thigh muscle strains and knee sprains at 2.28 and 2.07 per 1000 exposures, respectively.² These findings are consistent with reports of international-level soccer athletes.⁴ These lower extremity injuries have substantial short-term consequences, such as loss of participation, and the potential for long-term consequences, such as decreased physical activity⁵ and increased risk of osteoarthritis.^5–10 Nearly 20% of all soccer injuries were severe, requiring greater than 10 days of time lost from activity.² Knee ligament ruptures and leg fractures accounted for 35% of these injuries, many of which required surgical intervention and prolonged rehabilitative care; these patients also had a greatly increased risk of a secondary injury when they returned to soccer competition.^2,11The high injury rate in soccer players has persisted despite scientific advances in injury etiology,^12–17 screening techniques, and the identification of athletes who may be at greater risk.^18–25 Although injury-prevention programs have successfully decreased lower extremity injuries such as ankle sprains,^24,26–29 anterior cruciate ligament (ACL) injuries,^18,30,31 and hamstrings strains,^{20,24,29,32–34} they have not yet been widely adopted,³⁵ limiting their potential effects in soccer athletes.³⁶Although numerous training programs have been designed to prevent injury,^{3,24,26,29,31,32,37–55} few incorporate sport-specific components.^{37,38,41,42,56,57} Many of these programs have shown promising results in decreasing the risk of injury.^{18,37,38,41,58} However, extensive time, expert personnel, and special equipment are needed for these programs to be effective. To make injury-prevention programs as widely accessible as possible, the F-MARC 11+ program was developed by the Federation International de Football Association (FIFA) Medical Assessment and Research Center (F-MARC).⁵⁹ This program can be completed in a short time frame, takes minimal training to implement, and requires only a soccer ball, making it an attractive alternative for sport coaches, strength and conditioning professionals, and rehabilitation specialists already working with limited time and budgets. Thus far, 4 studies^37,38,41,60 have reported on the use of a version of the F-MARC 11+ program in adolescent males and females, with injury reductions ranging from 21% to 71%. In Norwegian handball players, similar training programs have produced a 49% reduction in injury risk⁴⁰ and 94% reduction in ACL injury risk.³⁹To our knowledge, the F-MARC 11+ has yet to be investigated for effectiveness in injury risk reduction in an American male collegiate soccer population. Therefore, our aim was to examine the effect of a sport-specific program implemented with athletic trainer supervision to track compliance, injury occurrence, and program performance quality. We hypothesized that the comprehensive, exercise-based soccer warm-up program (the F-MARC 11+) would be more effective than the traditional dynamic warm-up in preventing lower extremity injuries in male NCAA Division III collegiate soccer athletes.     

The Persistent Influence of Concussive Injuries on Cognitive Control and Neuroelectric Function

Context:

Increasing attention is being paid to the deleterious effects of sport-related concussion on cognitive and brain health.

Objective:

To evaluate the influence of concussion incurred during early life on the cognitive control and neuroelectric function of young adults.

Design:

Cross-sectional study.

Setting:

Research laboratory.

Patients or Other Participants:

Forty young adults were separated into groups according to concussive history (0 or 1+). Participants incurred all injuries during sport and recreation before the age of 18 years and were an average of 7.1 ± 4.0 years from injury at the time of the study.

Intervention(s):

All participants completed a 3-stimulus oddball task, a numeric switch task, and a modified flanker task during which event-related potentials and behavioral measures were collected.

Main Outcome Measure(s):

Reaction time, response accuracy, and electroencephalographic activity.

Results:

Compared with control participants, the concussion group exhibited decreased P3 amplitude during target detection within the oddball task and during the heterogeneous condition of the switch task. The concussion group also displayed increased N2 amplitude during the heterogeneous version of the switch task. Concussion history was associated with response accuracy during the flanker task.

Conclusions:

People with a history of concussion may demonstrate persistent decrements in neurocognitive function, as evidenced by decreased response accuracy, deficits in the allocation of attentional resources, and increased stimulus-response conflict during tasks requiring variable amounts of cognitive control. Neuroelectric measures of cognitive control may be uniquely sensitive to the persistent and selective decrements of concussion.Key Words: concussions, inhibition, mental flexibility, attention, P3, N2

Key Points

• • Seven years after concussion, participants displayed disrupted higher-order neurocognition in the form of chronically impaired attention, working memory, inhibition, and interference control.
• • The observed deficits in attention and conflict monitoring were only evident when cognitive demands were increased. Subtle deficits may remain unrecognized with other types of testing.

During the past decade, increased research efforts have been dedicated toward understanding the causes of brain and cognitive dysfunction stemming from concussive injuries. Concussions have been described as a “silent epidemic” by the Centers for Disease Control and Prevention,¹ and estimates of the incidence in the United States range from a conservative 300 000 per year² in 1997 to the more recent estimate of nearly 4 million cases per year.³ As 15%–20% of these injuries result from sport participation,⁴ sport-related concussion represents a growing public health concern. Concussion can be defined as a complex pathophysiologic process affecting the brain that is caused by a direct blow or an impulsive force transmitted to the head.⁵ Injured persons commonly display deficits in cognition, postural control, and symptoms,⁶ so the cost to society is heavy, with known negative effects on academic^7–9 and vocational¹⁰ performance. The annual economic burden of concussions approaches $17 billion in direct and indirect expenses in the United States,¹¹ warranting more investigation in the clinical and laboratory settings.Based on clinical evaluations, injured people typically return to a preinjury level of functioning within 7 to 10 days,¹² a time frame mirroring the acute neurometabolic cascade associated with concussion.¹³ Investigations of young adult athletes who have progressed past the acute stages of injury indicate normal performance on a variety of clinical tests,^14–17 leading to a general belief that concussion is a transient brain injury. However, the transient view of concussion has recently come into question, as a growing body of evidence illustrates numerous chronic nervous system dysfunctions and cognitive deficits stemming from these injuries.^18–28 Further, recent epidemiologic reports^16,29 reveal increased prevalence of mild cognitive impairment, dementia, and Alzheimer disease in retired contact-sport athletes. Evidence from these studies appears to diverge from the concept of concussion as a transient injury.Given this divergence and the lack of a definitive diagnostic tool, identifying aspects of cognition that are sensitive to subtle concussion-related deficits during the postacute phase is warranted. Because concussive injuries are inherently difficult to assess³⁰ and result in a wide variety of injury outcomes, assessing multiple aspects of cognitive functioning (eg, planning, memory, cognitive flexibility) may provide further insight into the nature and duration of these injuries.³¹The aspects of cognitive functioning described by Aubry et al³¹ fall under the domain of cognitive control, which designates a subset of goal-directed, self-regulatory operations involved in the selection, scheduling, and coordination of computational processes underlying perception, memory, and action.^32,33 Recent evaluations of the cognitive control of concussed persons demonstrate that tasks requiring this feature may be sensitive to detecting persistent cognitive deficits. For example, Pontifex et al²⁶ observed deficits in cognitive control, as indicated by decreased response accuracy during a modified flanker task, which requires variable amounts of inhibitory control (ie, an aspect of cognitive control) in previously concussed persons an average of 2.9 years after injury. Also using a flanker task, de Beaumont et al²⁰ observed decreased response accuracy in previously concussed persons an average of 34.7 years after injury relative to age-matched control participants. In addition, Ellemberg et al²² noted deficits in a group of previously concussed athletes 6 months after injury during the Stroop color-word test, which further measures inhibitory control, and the Tower of London DX task, which requires planning, working memory, and cognitive flexibility. Together, these studies provide convergent evidence that tasks requiring various aspects of cognitive control may be well suited for examining the relationship between concussion history and prolonged cognitive dysfunction. However, further examination of task specificity appears necessary if future researchers are to adequately detail this relationship.In addition to focusing on cognitive control, investigators have recently begun to incorporate sensitive measures of brain function in sport-related concussion research. Electroencephalography and event-related potentials (ERPs) in particular have emerged as valuable tools to evaluate covert neurocognitive deficits between stimulus engagement and response execution that stem from concussion. Therefore, electroencephalography may contribute to the development and refinement of differential diagnostic information for those with atypical clinical recovery after concussive injuries. The benefit of the ERP approach lies in its temporal sensitivity, which allows researchers to parse individual components in the stimulus-response relationship. Recent investigations^{19,23,34–36} have demonstrated the efficacy of neuroelectric measures in detecting neurocognitive deficits associated with a concussion history. Beyond providing a unique method for researchers and clinicians to monitor enduring neurocognitive alterations, ERPs may serve as a measure of treatment effectiveness.In particular, the P3 component has been of considerable interest in recent concussion research. The P3 component can be further divided into interrelated but distinct subcomponents, the P3b (P300) and P3a, which are differentiated by both the context in which they occur and scalp topography.³⁷ The P3b component, which is evoked in response to an infrequently occurring target stimulus, is believed to reflect the allocation of attentional resources (as indexed by component amplitude³⁷) and stimulus classification and evaluation speed (as indexed by component latency^38,39) and demonstrates a centroparietal maximum.³⁷ The P3a component, which is evoked in response to a distracter or novel stimulus, is believed to reflect the orienting of focal attention to such novel or distracting environmental stimuli and exhibits a frontocentral maximum.^37,40,41 Therefore, the P3 components can serve as valuable measures for researchers and clinicians to evaluate multiple aspects of cognition and brain function.Authors evaluating the persistent effects of concussion on neuroelectric indexes of cognition have observed decreased P3 amplitude^19,20,23 and increased P3 latency,²³ suggesting that concussive injuries may negatively affect attentional resource allocation and the speed of cognitive processing during environmental interactions. Further, this effect appears to endure: deficits have been observed in participants from approximately 3 years^19,23 to more than 34 years after injury.²⁰In addition to the P3 component, recent researchers^19,26,42 have also observed enduring concussion-related deficits in the neuroelectric correlates of conflict monitoring and adaptation during cognitive control performance. These results suggest that in addition to attentional resource allocation, concussive injuries may negatively affect indexes of conflict monitoring and adaptation. One neuroelectric index of conflict is the N2 component, which immediately precedes the P3 component. The frontocentral N2, observed during cognitive control tasks, has been linked to the conscious detection of deviance,^19,43 the mismatch of a stimulus with a mental template, and increased cognitive control over response inhibition.⁴⁴ Accordingly, N2 amplitudes are more negative during conditions of greater conflict,^44,45 arising from competition between the execution and inhibition of a single response.⁴⁶ Thus, the N2 component can serve as a valuable index of stimulus-response conflict during cognitively demanding environmental transactions.Accordingly, the goal of our study was to evaluate the chronic influence of concussion on cognitive and brain function using cognitive control tasks, which allowed us to measure neuroelectric function. We used tasks requiring cognitive flexibility, inhibitory control, and working memory. We hypothesized that, relative to uninjured control participants, those with a concussion history would demonstrate deficits in task performance (ie, reaction time and response accuracy) for conditions requiring the upregulation of cognitive control. Further, we predicted that participants with a concussion history would demonstrate a smaller P3 amplitude, reflecting deficits in the allocation of attentional resources during cognitive control operations relative to participants without a concussion history, and a longer P3 latency for those with a concussion history, indicating prolonged delays in the speed of cognitive processing. Last, we predicted that participants with a concussion history would demonstrate increased stimulus-response conflict, as evidenced by greater N2 amplitude relative to controls, during task conditions requiring the upregulation of cognitive control.     

Age-Related,Sport-Specific Adaptions of the Shoulder Girdle in Elite Adolescent Tennis Players

Context:

Tennis requires repetitive overhead movements that can lead to upper extremity injury. The scapula and the shoulder play a vital role in injury-free playing. Scapular dysfunction and glenohumeral changes in strength and range of motion (ROM) have been associated with shoulder injury in the overhead athlete.

Objective:

To compare scapular position and strength and shoulder ROM and strength between Swedish elite tennis players of 3 age categories (<14, 14–16, and >16 years).

Design:

Cross-sectional study.

Setting:

Tennis training sports facilities.

Patients or Other Participants:

Fifty-nine adolescent Swedish elite tennis players (ages 10–20 years) selected based on their national ranking.

Main Outcome Measure(s):

We used a clinical screening protocol with a digital inclinometer and a handheld dynamometer to measure scapular upward rotation at several angles of arm elevation, isometric scapular muscle strength, glenohumeral ROM, and isometric rotator cuff strength.

Results:

Players older than 16 years showed less scapular upward rotation on the dominant side at 90° and 180° (P < .05). Although all absolute scapular muscle strength values increased with age, there was no change in the body-weight–normalized strength of the middle (P = .9) and lower (P = .81) trapezius or serratus anterior (P = .17). Glenohumeral internal-rotation ROM and total ROM tended to decrease, but this finding was not statistically significant (P = .052 and P = .06, respectively). Whereas normalized internal-rotator strength increased from 14 to 16 years to older than 16 years (P = .009), normalized external-rotator and supraspinatus strength remained unchanged.

Conclusions:

Age-related changes in shoulder and scapular strength and ROM were apparent in elite adolescent tennis players. Future authors should examine the association of these adaptations with performance data and injury incidence.Key Words: upper extremity, scapular position, scapular muscle strength, range of motion, rotator cuff strength

Key Points

• Elite adolescent tennis players showed some sport-specific adaptations in glenohumeral internal-rotation range of motion, rotator cuff strength, and scapular upward rotation.
• Sport-specific adaptations seemed to change within the 10- to 20-years-old age range.

The tennis serve uses rapid upper extremity movements to create high racket and ball speeds. Optimal upper extremity strength, flexibility, and neuromuscular coordination are necessary for attaining a high-velocity outcome.^1,2Due to the high loads and forces put on the shoulder complex during serving and hitting, tennis players are at increased risk for shoulder pain. Injury risk seems to increase with age^3,4 and, despite some lack of evidence, has been suggested to be related to the level and volume of play.^3–5 Shoulder injuries in overhead athletes are commonly due to repetitive use,⁶ muscle fatigue,⁷ and may be related to scapular dyskinesis,^8,9 rotator cuff injury and weakness,¹⁰ or glenohumeral internal-rotation deficit,^11,12 resulting in int ernal impingement or labral injury (or both).^13,14In high-performance sports, athletes start full-time practice in early childhood, which overlaps with the period of skeletal and muscular development.^15,16 As a result of the high demands on joint mobility, muscle strength, and complex biomechanics in the shoulder girdle during overhead sport movements, sport-specific adaptations at the glenohumeral and scapulothoracic level may occur even during adolescence.^4,8,17Numerous authors have reported glenohumeral^18,19 and scapulothoracic^20,21 alterations in adult overhead sport populations. In addition, changes in glenohumeral range of motion³ and rotator cuff strength¹⁷ have been described in elite junior tennis players. Only recently have some studies^4,8 been published describing the scapular position, strength, and flexibility variables in this young population. However, in these investigations, only general data were established for the whole period of adolescence. The specific age-related changes within adolescents (11–18 years) and the progression over time in this age category were not apparent. Moreover, even though the literature highlights the importance of the coupled movements at the shoulder and scapulothoracic joint for optimal kinematics during the tennis serve,¹ to date no authors have combined glenohumeral and scapulothoracic measurements in adolescent tennis players. Therefore, the purpose of our study was to describe the age-related, sport-specific adaptations in the shoulder girdle in adolescent elite tennis players: in particular, glenohumeral rotational range of motion and strength and scapular upward rotation and muscle strength.     

Altered Knee and Ankle Kinematics During Squatting in Those With Limited Weight-Bearing–Lunge Ankle-Dorsiflexion Range of Motion

Context:

Ankle-dorsiflexion (DF) range of motion (ROM) may influence movement variables that are known to affect anterior cruciate ligament loading, such as knee valgus and knee flexion. To our knowledge, researchers have not studied individuals with limited or normal ankle DF-ROM to investigate the relationship between those factors and the lower extremity movement patterns associated with anterior cruciate ligament injury.

Objective:

To determine, using 2 different measurement techniques, whether knee- and ankle-joint kinematics differ between participants with limited and normal ankle DF-ROM.

Design:

Cross-sectional study.

Setting:

Sports medicine research laboratory.

Patients or Other Participants:

Forty physically active adults (20 with limited ankle DF-ROM, 20 with normal ankle DF-ROM).

Main Outcome Measure(s):

Ankle DF-ROM was assessed using 2 techniques: (1) nonweight-bearing ankle DF-ROM with the knee straight, and (2) weight-bearing lunge (WBL). Knee flexion, knee valgus-varus, knee internal-external rotation, and ankle DF displacements were assessed during the overhead-squat, single-legged squat, and jump-landing tasks. Separate 1-way analyses of variance were performed to determine whether differences in knee- and ankle-joint kinematics existed between the normal and limited groups for each assessment.

Results:

We observed no differences between the normal and limited groups when classifying groups based on nonweight-bearing passive-ankle DF-ROM. However, individuals with greater ankle DF-ROM during the WBL displayed greater knee-flexion and ankle-DF displacement and peak knee flexion during the overhead-squat and single-legged squat tasks. In addition, those individuals also demonstrated greater knee-varus displacement during the single-legged squat.

Conclusions:

Greater ankle DF-ROM assessed during the WBL was associated with greater knee-flexion and ankle-DF displacement during both squatting tasks as well as greater knee-varus displacement during the single-legged squat. Assessment of ankle DF-ROM using the WBL provided important insight into compensatory movement patterns during squatting, whereas nonweight-bearing passive ankle DF-ROM did not. Improving ankle DF-ROM during the WBL may be an important intervention for altering high-risk movement patterns commonly associated with noncontact anterior cruciate ligament injury.Key Words: knee flexion, knee valgus, knee varus, anterior cruciate ligament, squat, jump landing

Key Points

• Nonweight-bearing ankle-dorsiflexion range of motion was not associated with changes in ankle or knee kinematics during the overhead-squat, single-legged squat, or jump-landing task.
• Greater ankle-dorsiflexion range of motion during the weight-bearing lunge resulted in greater sagittal-plane motion at the knee and ankle during the squatting tasks but not the jump landing.
• Compared with nonweight-bearing passive measures, ankle-dorsiflexion range of motion during the weight-bearing lunge may be a more sensitive measure for identifying those with high-risk movement patterns.

An estimated 350 000 anterior cruciate ligament (ACL) reconstructions are performed annually in the United States,¹ with most of those injuries occurring during sport participation by individuals between 15 and 25 years old.^2,3 Recent estimates have illustrated a national increase in ACL injuries of 67.8% during a 10-year period.⁴ In addition to those concerning numbers, 70% of ACL injuries result from noncontact mechanisms, defined as no contact with another player or piece of equipment, such as plant-and-cut maneuvers, landing from a jump, and decelerating.^5,6 The high incidence of noncontact ACL injury is driving researchers to investigate possible biomechanical and neuromuscular factors that may contribute to ACL injury.Dynamic maneuvers, such as the overhead-squat (OHS),⁷ single-legged squat (SLS),⁸ and jump-landing (JL)⁹ tasks, have been used in laboratory and clinical settings to elucidate faulty lower extremity movement patterns and to identify individuals potentially at risk for ACL injury. Some of the key patterns of movement identified are side-to-side (frontal-plane) or rotational (transverse-plane) movements at the knee because those movements place the greatest load on the ACL in combination with an anterior tibial shear force (sagittal plane).¹⁰ Anterior cruciate ligament loading is exacerbated when the knee is in a minimally flexed or hyperextended position in conjunction with a large quadriceps muscle contraction.^11,12 Noncontact ACL injury mechanisms are often described as landing in a relatively extended knee position (sagittal plane) combined with frontal- and transverse-plane loading.¹² Movement at adjacent joints also influences knee loading. Researchers^7,13,14 have identified a potential relationship between limited dorsiflexion range of motion (DF-ROM) in the ankle and knee kinematics, such as medial knee displacement, which may increase the risk of ACL injury. Ideally, those squatting and JL movements would include primarily sagittal-plane motion at all lower extremity joints to perform properly and absorb and dissipate the landing forces.¹⁵ Restrictions in the ability to move through ankle DF during weight bearing can interfere with performance by potentially increasing the plantar-flexion moment when the ankle is dorsiflexed¹⁶ and restricting the forward rotation of the shank at the ankle when the foot is in contact with the ground.¹⁷ Limitations in ankle-DF displacement are often accompanied by less sagittal-plane motion at proximal joints, such as the knee and trunk.^15,18 Therefore, ankle-DF restrictions may contribute to limited sagittal-plane motion at the knee and thereby contribute to compensatory increases in frontal- and transverse-plane motions that are potentially injurious to the ACL.Less DF-ROM assessed passively in a nonweight-bearing (NWB) position has been associated with greater medial-knee displacement during a variety of tasks.^7,14 Bell et al⁷ studied individuals with medial-knee displacement, which is a clinical observation of dynamic valgus collapse, and observed that participants who displayed medial-knee displacement during an OHS had approximately 20% less NWB, passive ankle DF than did those participants without medial-knee displacement. Furthermore, the medial-knee displacement observed during the OHS was corrected when a 2-in (5.08-cm) lift was placed under the heel; the correction may have occurred because of the increased tibial angle in the anterior direction. Less passive DF-ROM assessed in NWB movements has also been associated with greater frontal-plane knee excursion during a double-legged drop-landing in young female soccer players¹⁴ and with decreased knee-flexion displacement during a jump-landing task.¹⁹Other authors have investigated ankle-DF motion during dynamic movements in relation to knee kinematics, with contrasting findings. Compared with men, women with greater DF-ROM measured during SLS²⁰ and double-legged drop landings²¹ demonstrated greater maximum knee-valgus angles. This body of research suggests that ankle DF-ROM may contribute to the amount of knee valgus (frontal plane) and knee flexion (sagittal plane) an individual uses during dynamic movement, but the relationship is unclear and requires further investigation.Previous examinations^7,14,19 of the relationship between ankle DF-ROM and knee kinematics may be limited because of the NWB, passive assessments that were often used. Weight-bearing measures of ankle DF-ROM may provide a better representation of the available ROM during functional, weight-bearing tasks.²² However, previous authors have not, to our knowledge, investigated the relationship between knee kinematics during dynamic movement and separate weight-bearing and NWB ankle DF-ROM assessments. In addition, no previous researchers, to our knowledge, have intentionally recruited a participant population with known limitations in ankle DF-ROM. Therefore, the purpose of our study was to investigate knee and ankle kinematics during dynamic tasks in participants who were identified as having limited ankle DF-ROM and to compare the results with those of participants who had normal ankle DF-ROM. Ankle-DF motion was assessed passively through both weight-bearing and NWB techniques before testing, and total displacement during dynamic movement was calculated. The goal of comparing the ROM of normal and limited groups was to find an assessment that could be used clinically to indicate how an individual will perform during a more functional task. We hypothesized that individuals with less DF-ROM, both NWB and weight bearing, would display kinematics associated with ACL loading (less sagittal-plane motion and greater frontal-plane motion) during an OHS, SLS, and JL task.     

Neuromuscular Fatigue and Tibiofemoral Joint Biomechanics When Transitioning From Non–Weight Bearing to Weight Bearing

Context:Fatigue is suggested to be a risk factor for anterior cruciate ligament injury. Fatiguing exercise can affect neuromuscular control and laxity of the knee joint, which may render the knee less able to resist externally applied loads. Few authors have examined the effects of fatiguing exercise on knee biomechanics during the in vivo transition of the knee from non–weight bearing to weight bearing, the time when anterior cruciate ligament injury likely occurs.Objective:To investigate the effect of fatiguing exercise on tibiofemoral joint biomechanics during the transition from non–weight bearing to early weight bearing.Design:Cross-sectional study.Setting:Research laboratory.Intervention(s):Participants were tested before (preexercise) and after (postexercise) a protocol consisting of repeated leg presses (15 repetitions from 10°–40° of knee flexion, 10 seconds'' rest) against a 60% body-weight load until they were unable to complete a full bout of repetitions.Results:The axial compressive force (351.8 ± 44.3 N versus 374.0 ± 47.9 N; P = .018), knee-flexion excursion (8.0° ± 4.0° versus 10.2° ± 3.7°; P = .046), and anterior tibial translation (6.7 ± 1.7 mm versus 8.2 ± 1.9 mm; P < .001) increased from preexercise to postexercise. No significant correlations were noted.Conclusions:Neuromuscular fatigue may impair initial knee-joint stabilization during weight acceptance, leading to greater accessory motion at the knee and the potential for greater anterior cruciate ligament loading.Key Words: knee, anterior cruciate ligament, axial loading

Key Points

• After closed chain exercise, participants demonstrated an increase in anterior tibial translation during simulated lower extremity weight acceptance.
• Observed alterations of knee biomechanics in a fatigued state may suggest increased anterior cruciate ligament strain during the latter part of the competition.

The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments in the knee.^1–4 Injuries to the ACL frequently result from noncontact mechanisms, occurring when the knee is near full extension at the time of foot strike during activities such as landing, cutting, and deceleration-type maneuvers.⁵ Neuromuscular fatigue has been defined as any exercise-induced loss in the ability to produce force with a muscle or muscle group, involving processes at all levels of the motor pathway between the brain and the muscle.^6–8 Furthermore, fatigue has been suggested as a contributing risk factor for noncontact ACL injury^9–14 because the risk of noncontact knee injuries appears to increase later in games.^15,16 Specifically, prolonged exercise, which contributes to the delayed activation of muscles agonistic to the ACL,^13,17 has been suggested to increase risk of knee injury.¹³The quadriceps and hamstrings play a critical role in providing dynamic stability of the knee joint during sports activities,¹⁸ so various lower extremity fatigue protocols have been used to decrease the force-producing capabilities of these muscles.^10,19,20 Commonly, fatigue has been induced using isokinetic exercise protocols.^12,14,21,22 However, the true nature of muscle function and its effect on functional knee-joint biomechanics during sporting activity is likely difficult to assess from isolated forms of isometric, concentric, or eccentric contractions. Exercise that results in complete volitional exhaustion of a single muscle or muscle group rarely occurs during functional activity. Therefore, fatigue protocols that involve total lower extremity actions incorporating submaximal stretch-shortening cycles^23,24 may better mimic the type of muscular fatigue associated with prolonged weight-bearing activity.A number of authors^23,25,26 have examined the effect of lower extremity muscle fatigue on knee-joint biomechanics during jumping and landing activities. These results suggest that, depending on the fatigue protocol and task used, knee-flexion excursion (KF_EXC) may be either decreased or increased postexercise, thus modulating joint stiffness.^25,27 These changes in KF_EXC appear to primarily depend on the peak knee flexion obtained,^11,27 given that little to no change in the initial knee-flexion landing angle has been reported at ground contact in response to fatiguing exercise.^9,20 Moran et al²⁸ examined the effect of an incremental treadmill protocol and reported that exercise-induced alterations in tibial peak-impact acceleration were not attributed to changes in the knee angles at foot contact during a drop jump. This suggests that fatiguing exercise does not alter the initial knee-position angle at ground contact, but it may have a profound effect on knee-joint biomechanics during the weight-acceptance phase of landing. Because ACL injuries typically occur near the time of foot strike^1,4 with the knee in shallow flexion (average, 23° of initial knee flexion),²⁹ understanding the effect of fatiguing exercise on knee-joint biomechanics during this early weight-acceptance phase may lend further insight into the role of fatigue in ACL injury mechanisms.As the knee transitions from non–weight bearing (NWB) to weight bearing (WB), the natural anterior translation of the tibia (ATT) relative to the femur at low knee-flexion angles (eg, 15°–30°)^30,31 is restrained by the ACL.³¹ Greater axial loads^30,32,33 and slowing of the quadriceps and hamstrings onset times in response to an anterior tibial load may contribute to increased ATT¹⁴ at shallow knee-flexion angles; hence, fatigue may compromise the biomechanics of the tibiofemoral joint during weight acceptance, thereby modifying the strain placed upon the ACL with continued loading and subsequent maneuvers (eg, plant and cut). This may be particularly problematic in landing situations where KF_EXC decreases in response to fatiguing exercise.^9,25,34 Although decreased KF_EXC may represent a compensatory strategy to prevent collapse of the body due to fatigue of the quadriceps muscles,^10,34 the reduced KF_EXC may increase axial loads at the knee joint, and these greater axial loads may increase the amount of ATT.³⁵The purpose of our study was to investigate the effects of a lower extremity exercise protocol on tibiofemoral-joint biomechanics as the knee transitioned from NWB to WB in vivo. Based on previous fatigue studies of submaximal total lower extremity actions,^9,25 our expectation was that fatiguing exercise would decrease KF_EXC, increase axial compressive force (ACF), and subsequently increase ATT during transition from NWB to WB.     

Joint Stability Characteristics of the Ankle Complex in Female Athletes With Histories of Lateral Ankle Sprain,Part II: Clinical Experience Using Arthrometric Measurement

Context:

This is part II of a 2-part series discussing stability characteristics of the ankle complex. In part I, we used a cadaver model to examine the effects of sectioning the lateral ankle ligaments on anterior and inversion motion and stiffness of the ankle complex. In part II, we wanted to build on and apply these findings to the clinical assessment of ankle-complex motion and stiffness in a group of athletes with a history of unilateral ankle sprain.

Objective:

To examine ankle-complex motion and stiffness in a group of athletes with reported history of lateral ankle sprain.

Design:

Cross-sectional study.

Setting:

University research laboratory.

Patients or Other Participants:

Twenty-five female college athletes (age = 19.4 ± 1.4 years, height = 170.2 ± 7.4 cm, mass = 67.3 ± 10.0 kg) with histories of unilateral ankle sprain.

Intervention(s):

All ankles underwent loading with an ankle arthrometer. Ankles were tested bilaterally.

Main Outcome Measure(s):

The dependent variables were anterior displacement, anterior end-range stiffness, inversion rotation, and inversion end-range stiffness.

Results:

Anterior displacement of the ankle complex did not differ between the uninjured and sprained ankles (P = .37), whereas ankle-complex rotation was greater for the sprained ankles (P = .03). The sprained ankles had less anterior and inversion end-range stiffness than the uninjured ankles (P < .01).

Conclusions:

Changes in ankle-complex laxity and end-range stiffness were detected in ankles with histories of sprain. These results indicate the presence of altered mechanical characteristics in the soft tissues of the sprained ankles.Key Words: ankle instability, joint laxity measurement, ankle sprains

Key Points

• Ankles with histories of lateral sprain showed more ankle-complex inversion rotation and less anterior and inversion stiffness than uninjured ankles.
• The mechanical property of stiffness might be important to understanding how lateral ankle sprain affects ligamentous elasticity and joint stability.
• These clinically important findings indicate that increased ankle-complex laxity is not the only identifiable mechanical tissue characteristic that changes after lateral ankle sprain.

Ankle sprain is one of the most common injuries encountered during sporting activity.¹ Lateral ankle sprain injury can result in changes to the ligaments and surrounding soft tissues that often lead to mechanical instability and functional insufficiencies.^2–7 Equally concerning is the recurrence rate after an initial sprain.⁸ A search of epidemiologic and cohort studies identified history of lateral ankle sprain as a consistent risk factor associated with ankle sprain in sport.^8–12 Our understanding of the connection between history of ankle sprain and mechanical measures of ankle stability is unclear because not all ankles develop mechanical instability after 1 or more ankle sprains.^7,13Increased ligament laxity can result from a tear or lengthening of the involved ligamentous structures supporting the joint or less-than-optimal healing of the injured tissues.² Individuals with histories of ankle sprain present with increased joint laxity and persistent symptoms, such as the feeling of or actual giving way of the ankle during jumping and cutting activities.^14–16 However, some authors have not reported findings of increased laxity in the sprained ankles despite the presence of functional insufficiencies, such as impaired proprioception, altered neuromuscular control, strength deficits, and diminished postural control.^6,17The passive stiffness characteristics of a joint are created in part by the viscoelastic properties of the soft tissues that surround and support the joint.¹⁸ Leardini et al¹⁹ reported that passive stiffness provided by the soft tissue structures is a vital component of joint stability. Thus, the mechanical property of stiffness may be important to understanding joint stability after injury. Only Wikstrom et al²⁰ have investigated passive ankle-joint stiffness in people who reported experiencing ankle sprains. They found no differences in anterior laxity or anterior stiffness of the ankle between individuals with or without reported functional ankle instability. In a later study, Wikstrom et al⁷ reported that patients who had histories of ankle sprain and presented with no signs or symptoms of chronic ankle instability (CAI) and patients with CAI had increased anterior ankle-joint stiffness relative to uninjured control participants. When jointly examined, these previous reports appear specious because laxity and stiffness are inversely related. We wanted to build on the work of Wikstrom et al^7,20 and also examine the effects of previous lateral ankle sprain on inversion ankle-complex motion and stiffness. Therefore, the purpose of our clinically based study was to determine ankle-complex motion and stiffness in a group of athletes with a reported history of lateral ankle sprain. We hypothesized that ankles with histories of lateral sprain would demonstrate altered motion and stiffness characteristics when compared with the uninjured ankles.     

Gait Kinematics After Taping in Participants With Chronic Ankle Instability

Context:

Chronic ankle instability is characterized by repetitive lateral ankle sprains. Prophylactic ankle taping is a common intervention used to reduce the risk of ankle sprains. However, little research has been conducted to evaluate the effect ankle taping has on gait kinematics.

Objective:

To investigate the effect of taping on ankle and knee kinematics during walking and jogging in participants with chronic ankle instability.

Design:

Controlled laboratory study.

Setting:

Motion analysis laboratory.

Patients or Participants:

A total of 15 individuals (8 men, 7 women; age = 26.9 ± 6.8 years, height = 171.7 ± 6.3 cm, mass = 73.5 ± 10.7 kg) with self-reported chronic ankle instability volunteered. They had an average of 5.3 ± 3.1 incidences of ankle sprain.

Intervention(s):

Participants walked and jogged in shoes on a treadmill while untaped and taped. The tape technique was a traditional preventive taping procedure. Conditions were randomized.

Main Outcome Measure(s):

Frontal-plane and sagittal-plane ankle and sagittal-plane knee kinematics were recorded throughout the entire gait cycle. Group means and 90% confidence intervals were calculated, plotted, and inspected for percentages of the gait cycle in which the confidence intervals did not overlap.

Results:

During walking, participants were less plantar flexed from 64% to 69% of the gait cycle (mean difference = 5.73° ± 0.54°) and less inverted from 51% to 61% (mean difference = 4.34° ± 0.65°) and 76% to 81% (mean difference = 5.55° ± 0.54°) of the gait cycle when taped. During jogging, participants were less dorsiflexed from 12% to 21% (mean difference = 4.91° ± 0.18°) and less inverted from 47% to 58% (mean difference = 6.52° ± 0.12°) of the gait cycle when taped. No sagittal-plane knee kinematic differences were found.

Conclusions:

In those with chronic ankle instability, taping resulted in a more neutral ankle position during walking and jogging in shoes on a treadmill. This change in foot positioning and the mechanical properties of the tape may explain the protective aspect of taping in preventing lateral ankle sprains.Key Words: external ankle supports, ankle prophylactic measures, recurrent ankle sprains

Key Points

• Taping the ankles of participants with chronic ankle instability resulted in more neutral positioning when they walked or jogged in shoes on a treadmill.
• Taping may protect the ankle by way of its mechanical properties and its neuromuscular effect on ankle position.

Lateral ankle sprains are very common injuries,¹ comprising an estimated 85% of all ankle injuries.^2,3 A history of ankle sprain has been found to be the leading risk factor in predicting future sprains.^4–6 Up to an estimated 70% of individuals who incur an initial ankle sprain and who are exposed to sports with a high risk of ankle-joint injuries will develop chronic ankle instability (CAI),^7,8 which is characterized by residual symptoms for at least 1 year after the initial ankle sprain.^8–10 Although the high prevalence of CAI is known, very little is actually understood regarding the mechanism or prevention of lateral ankle sprains.Gait kinematic alterations in those with a history of lateral ankle sprain have been hypothesized to contribute to CAI.^11–13 In a cadaver study¹⁴ of foot–floor clearance, inverting the foot 10°, regardless of plantar flexion, caused a collision between the lateral aspect of the foot and the floor, resulting in an ankle sprain. Individuals with CAI underestimate the combined motions of plantar flexion and inversion during passive joint position sense testing.¹⁵ These alterations in joint position sense may lead to alterations in kinematics during gait, which may contribute to ankle sprains and instability; an increased plantar-flexion touch-down position upon initial contact is known to increase the risk of ankle-joint injury.^14,16 Recently, researchers have compared the ankle kinematics of CAI participants with healthy controls while walking and jogging on a treadmill barefoot^17,18 and shod¹⁹ and walking on a walkway while shod.²⁰ Compared with healthy controls, frontal-plane and sagittal-plane kinematics were altered during various aspects of the gait cycle, and these changes are believed to contribute to repetitive incidences of ankle sprains.Prophylactic ankle taping is a common means of reducing the risk of injury to the lateral ankle ligaments, including recurrent ankle sprains.^21,22 The purpose of ankle taping is to restrict ankle inversion and plantar-flexion motion.^22,23 In healthy people, taping reduces sagittal-plane range of motion compared with the untaped condition while running, cutting, and landing from a drop.^24–26 Sagittal-plane kinematics during walking have been reported to be altered at foot contact and toe-off in individuals with CAI wearing an ankle brace.²⁷ During a functional drop landing, those with CAI demonstrated a decreased plantar-flexion angle immediately (50 milliseconds) before and at initial contact while wearing prophylactic ankle-joint taping compared with the untaped condition.²⁸ Previous researchers, however, have focused on discrete time points²⁷ or a specific window²⁸ during the gait cycle. We know of no literature evaluating frontal-plane and sagittal-plane kinematics during the entire walking and jogging gait cycle when CAI participants were taped.Therefore, the purpose of our study was to compare frontal-plane and sagittal-plane ankle kinematics in shod CAI participants while walking and jogging on a treadmill with or without traditional ankle taping. The secondary purpose was to evaluate sagittal-plane knee kinematics to determine if changes occurred with ankle taping. We evaluated kinematics at the knee to determine if kinematic alterations at the ankle affected movement up the kinetic chain.     

Osteoarthritis Prevalence Following Anterior Cruciate Ligament Reconstruction: A Systematic Review and Numbers-Needed-to-Treat Analysis

Objective:

To determine the prophylactic capability of anterior cruciate ligament (ACL) reconstruction in decreasing the risk of knee osteoarthritis (OA) when compared with ACL-deficient patients, as well as the effect of a concomitant meniscectomy. We also sought to examine the influence of study design, publication date, and graft type as well as the magnitude of change in physical activity from preinjury Tegner scores in both cohorts.

Data Sources:

We searched Web of Science and PubMed databases from 1960 through 2012 with the search terms osteoarthritis, meniscectomy, anterior cruciate ligament, anterior cruciate ligament reconstruction, and anterior cruciate ligament deficient.

Study Selection:

Articles that reported the prevalence of tibiofemoral or patellofemoral OA based on radiographic assessment were included. We calculated numbers needed to treat and relative risk reduction with associated 95% confidence intervals for 3 groups (1) patients with meniscal and ACL injury, (2) patients with isolated ACL injury, and (3) total patients (groups 1 and 2).

Data Extraction:

A total of 38 studies met the criteria. Of these, 27 assessed the presence of tibiofemoral osteoarthritis in patients treated with anterior cruciate ligament reconstruction.

Data Synthesis:

Overall, ACL reconstruction (ACL-R) yielded a numbers needed to treat to harm of 16 with a relative risk increase of 16%. Anterior cruciate ligament reconstruction along with meniscectomy yielded a numbers needed to treat to benefit of 15 and relative risk reduction of 11%. Isolated ACL-R showed a numbers needed to treat to harm of 8 and relative risk increase of 43%. Activity levels were decreased in both ACL-R (d = −0.90; 95% confidence interval = 0.77, 1.13) and ACL-deficient (d = −1.13; 95% confidence interval = 0.96, 1.29) patients after injury.

Conclusions:

The current literature does not provide substantial evidence to suggest that ACL-R is an adequate intervention to prevent knee osteoarthritis. With regard to osteoarthritis prevalence, the only patients benefiting from ACL-R were those undergoing concomitant meniscectomy with reconstruction.Key Words: knee, meniscectomy, activity level, absolute risk reduction

Key Points

• The current literature does not support the prophylactic benefit of anterior cruciate ligament reconstruction in reducing the prevalence of knee osteoarthritis after anterior cruciate ligament injury.
• Meniscal status and graft type affect the risk of knee osteoarthritis after anterior cruciate ligament injury and reconstruction.

The anterior cruciate ligament (ACL) is a major stabilizer of the knee, restricting anterior tibial translation and rotational forces at the tibiofemoral joint. Anterior cruciate ligament rupture occurs in approximately 250 000 Americans each year.^1,2 Anterior cruciate ligament deficiency (ACL-D) results in pain, increased instability, and altered function in a large proportion of patients.³ Total medical costs encompassing diagnosis, surgical reconstruction, and postoperative rehabilitation of ACL injuries total $3 billion in the United States annually.⁴The development of posttraumatic knee osteoarthritis (OA) has been established as a significant risk after ACL injury.^5,6 Knee OA is a chronic, progressive disease that leads to increased disability and significant economic burden on the health care system.^7,8 The mechanisms that contribute to the development of OA after ACL injury are not completely understood, yet current hypotheses have focused on influences from altered biochemical processes,⁹ biomechanical alterations,¹⁰ and deficits in neuromuscular function.^8,11 It has been suggested that ACL reconstruction (ACL-R) may aid patients in regaining proper joint kinematics, possibly minimizing the abnormal stresses that could occur with ACL-D.^8,12,13 Although ACL-R is primarily performed to regain stability after ACL rupture, a long-term goal of this procedure is to decrease the risk of developing knee OA and improve long-term joint health.^12,13Concomitant meniscal injury requiring meniscectomy after ACL rupture cannot be ignored as a contributing factor to knee OA. Meniscal damage is associated with approximately 25% to 45% of ACL ruptures^8,14–16 and has been reported to be as high as 50%.¹⁷ Meniscal damage and ACL injury increase the risk of knee OA, likely a result of diminished intra-articular energy attenuation and altered arthrokinematics.¹⁸ Isolated ACL-R and ACL-R with meniscectomy are common surgical procedures, but we do not completely understand the ability of these procedures to decrease the risk of OA development.Therefore, the purpose of our article is to systematically review the literature to determine the prophylactic capacity of ACL-R in decreasing the prevalence of knee OA compared with ACL-D patients receiving only conservative treatment.