The Utility of Functional Data Analyses to Reveal Between-Limbs Asymmetries in Those With a History of Anterior Cruciate Ligament Reconstruction

ContextResearchers have traditionally used motion capture to quantify discrete data points (peak values) during hop testing. However, these analyses restrict the evaluation to a single time point (ie, certain percentage of stance) and provide only a narrow view of movement. Applying more comprehensive analyses may help investigators identify important characteristics that are masked by discrete analyses often used to screen patients for activity.ObjectiveTo examine the utility of functional data analyses to reveal asymmetries that are undetectable using discrete (ie, single time point) evaluations in participants with a history of anterior cruciate ligament reconstruction (ACLR) who achieved clinical hop symmetry.DesignCross-sectional study.SettingLaboratory.Patients or Other ParticipantsFifteen participants with unilateral ACLR (age = 21 ± 3 years, time from surgery = 4 ± 3 years) and 15 control participants without ACLR (age = 23 ± 2 years).Intervention(s)Lower extremity biomechanics during the triple–hop-for-distance task for the ACLR and contralateral limbs of patients and a representative limb of control participants were measured.Main Outcome Measure(s)Peak sagittal-plane joint power, joint work, and power profiles were determined.ResultsUsing discrete analyses, we identified lower peak knee power and work in the ACLR limb compared with the contralateral and control limbs (P < .05) but were unable to demonstrate differences at the ankle or hip. Using functional data analyses, we observed asymmetries at the ankle, knee, and hip between the ACLR and contralateral or control limbs throughout stance (P < .05), and it was revealed that these asymmetries stemmed from knee power deficits that were prominent during early loading.ConclusionsDespite achieving hop-distance symmetry, the ACLR knees absorbed less power. Although this information was revealed using discrete analyses, underlying asymmetries at the ankle and hip were masked. Using functional data analyses, we found interlimb asymmetries at the ankle, knee, and hip. Importantly, we found that functional data analyses more fully elucidated the extent and source of asymmetries, which can be used by clinicians and researchers alike to aid in clinical decision making.     

Gait Biomechanics in Individuals Meeting Sufficient Quadriceps Strength Cutoffs After Anterior Cruciate Ligament Reconstruction

ContextQuadriceps weakness is associated with disability and aberrant gait biomechanics after anterior cruciate ligament reconstruction (ACLR). Strength-sufficiency cutoff scores, which normalize quadriceps strength to the mass of an individual, can predict who will report better function after ACLR. However, whether gait biomechanics differ between individuals who meet a strength-sufficiency cutoff (strong) and those who do not (weak) remains unknown.ObjectiveTo determine whether vertical ground reaction force, knee-flexion angle, and internal knee-extension moment differ throughout the stance phase of walking between individuals with strong and those with weak quadriceps after ACLR.DesignCase-control study.SettingLaboratory.Patients or Other ParticipantsIndividuals who underwent unilateral ACLR >12 months before testing were dichotomized into strong (n = 31) and weak (n = 116) groups.Main Outcome MeasuresMaximal isometric quadriceps strength was measured at 90° of knee flexion using an isokinetic dynamometer and normalized to body mass. Individuals who demonstrated maximal isometric quadriceps strength ≥3.0 N·m·kg⁻¹ were considered strong. Three-dimensional gait biomechanics were collected at a self-selected walking speed. Biomechanical data were time normalized to 100% of stance phase. Vertical ground reaction force was normalized to body weight (BW), and knee-extension moment was normalized to BW × height. Pairwise comparison functions were calculated for each outcome to identify between-groups differences for each percentile of stance.ResultsVertical ground reaction force was greater in the weak group for the first 22% of stance (peak mean difference [MD] = 6.2% BW) and less in the weak group between 36% and 43% of stance (MD = 1.4% BW). Knee-flexion angle was greater (ie, more flexion) in the strong group between 6% and 52% of stance (MD = 2.3°) and smaller (ie, less flexion) between 68% and 79% of stance (MD = 1.0°). Knee-extension moment was greater in the strong group between 7% and 62% of stance (MD = 0.007 BW × height).ConclusionsIndividuals with ACLR who generated knee-extension torque ≥3.0 N·m·kg⁻¹ exhibited different biomechanical gait profiles than those who could not. More strength may allow for better energy attenuation after ACLR.     

Explosive Quadriceps Strength Symmetry and Landing Mechanics Limb Symmetry After Anterior Cruciate Ligament Reconstruction in Females

ContextEmerging evidence suggests that a lower quadriceps rate of torque development (RTD) after anterior cruciate ligament (ACL) reconstruction (ACLR) may be associated with altered landing mechanics. However, the influence of quadriceps RTD magnitude and limb symmetry on landing mechanics limb symmetry remains unknown.ObjectiveTo assess the influence of quadriceps RTD magnitude and limb symmetry on limb symmetry in sagittal-plane landing mechanics during functional landing tasks in females with or without ACLR.DesignCross-sectional study.SettingLaboratory.Patients or Other ParticipantsA total of 19 females with ACLR (age = 19.21 ± 1.81 years, height = 164.12 ± 6.97 cm, mass = 63.79 ± 7.59 kg, time after surgery = 20.05 ± 9.50 months) and 19 females serving as controls (age = 21.11 ± 3.28 years, height = 167.26 ± 7.26 cm, mass = 67.28 ± 9.25 kg).Main Outcome Measure(s)Landing mechanics were assessed during a double-legged (DL) jump-landing task, a single-legged jump-landing task, and a side-cutting task. Quadriceps RTD was collected during isometric muscle contractions. Separate stepwise multiple linear regression models were used to determine the variance in limb symmetry in the sagittal-plane knee moment at initial contact, peak vertical ground reaction force, and loading rate that could be explained by quadriceps RTD magnitude or limb symmetry, group (ACLR or control), and their interaction.ResultsIn the ACLR group, greater limb symmetry in quadriceps RTD was associated with greater symmetry in sagittal-plane knee moment at initial contact during the DL task (P = .004). Peak vertical ground reaction force and loading rate could not be predicted by quadriceps RTD magnitude or limb symmetry, group, or their interaction during any task.ConclusionsDeveloping greater symmetry but not magnitude in quadriceps RTD likely enabled more symmetric sagittal-plane knee landing mechanics during the DL task in the ACLR group and thus may reduce the risk of a second ACL injury. Such a protective effect was not found during the single-legged or side-cutting tasks, which may indicate that these tasks do not allow for the compensatory landing mechanism of shifting load to the uninvolved limb that was possible during the DL task.     

Drop-Landing Performance and Knee-Extension Strength After Anterior Cruciate Ligament Reconstruction

Context

Individuals with a history of anterior cruciate ligament reconstruction (ACLR) are at greater risk of reinjury and developing early-onset osteoarthritis due to persistent abnormal joint loading. Real-time clinical assessment tools may help identify patients experiencing abnormal movement patterns after ACLR.

Objective

To compare performance on the Landing Error Scoring System (LESS) between participants with ACLR and uninjured control participants and to determine the relationship between LESS score and knee-extension strength in these participants.

Design

Controlled laboratory study.

Setting

Research laboratory.

Patients or Other Participants

Forty-six recreationally active participants, consisting of 22 with ACLR (12 men, 10 women; age = 22.5 ± 5.0 years, height = 172.8 ± 7.2 cm, mass = 74.2 ± 15.6 kg, body mass index = 24.6 ± 4.0) and 24 healthy control participants (12 men, 12 women; age = 21.7 ± 3.6 years, height = 168.0 ± 8.8 cm, mass = 69.2 ± 13.6 kg, body mass index = 24.3 ± 3.2) were enrolled.

Main Outcome Measure(s)

Bilateral normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/kg) and LESS scores were measured during a single testing session. We compared LESS scores between groups using a Mann-Whitney U test and the relationships between LESS scores and normalized knee-extension MVIC torque using Spearman ρ bivariate correlations.

Results

The ACLR participants had a greater number of LESS errors (6.0 ± 3.6) than healthy control participants (2.8 ± 2.2; t₄₄ = −3.73, P = .002). In ACLR participants, lower normalized knee-extension MVIC torque in the injured limb (ρ = −0.455, P = .03) was associated with a greater number of landing errors.

Conclusions

Participants with ACLR displayed more errors while landing. The occurrence of landing errors was negatively correlated with knee-extension strength, suggesting that weaker participants had more landing errors. Persistent quadriceps weakness commonly associated with ACLR may be related to a reduced quality of lower extremity movement during dynamic tasks.Key Words: quadriceps weakness, Landing Error Scoring System, knee-extension torque

Key Points

• Participants with anterior cruciate ligament reconstruction had more landing errors than healthy control participants.
• Landing errors were negatively correlated with knee-extension strength, suggesting that weaker participants demonstrated more landing errors.
• Persistent quadriceps weakness, which is associated with anterior cruciate ligament reconstruction, may be related to poorer-quality lower extremity movement during dynamic tasks.

Anterior cruciate ligament (ACL) injuries are common in the athletic population, and ACL reconstruction (ACLR) is the most common intervention to restore joint stability.¹ However, despite successful surgical intervention, ACL injury may result in persistent lower extremity weakness and negative long-term effects on joint health.² Currently, active individuals are permitted to return to sport based on a variable set of criteria established by clinicians and supported by research; yet in many cases, these criteria do not include quantifiable analyses of movement patterns that measure persistent alterations in knee-joint loading and prospectively monitor the potential risk for knee injury.^3–5 When making decisions regarding return to activity and rehabilitation strategies, clinicians must have access to easy, time-efficient tools that produce objective clinical findings to better assess individuals with a history of injury.Individuals with ACLR experience neuromuscular and sensorimotor deficits that can persist long after completion of rehabilitation.^2,6 These deficits result in reduced physical activity level, patient-reported knee function, and quadriceps strength and activation and alterations in functional performance^7–11 that may have major implications for knee-joint reinjury^7,12 and the development of posttraumatic osteoarthritis (OA).^13–15 Assessing landing biomechanics after ACLR provides a clinically relevant method to evaluate global lower extremity function, including muscle strength and postural control during a common functional movement pattern. In addition, alterations in frontal-plane and sagittal-plane biomechanics have been hypothesized to predict which individuals may be at risk for reinjury or long-term joint degeneration due to persistent aberrant joint loading.¹⁶ Most studies have focused on jump landings in the healthy population to understand the risk factors for initial ACL injury, but the neuromuscular and motor-control demands present during jump-landing tasks also provide a useful tool for assessing recovery and post-ACLR injury risk.¹⁷ During double-limb landings after ACLR, individuals have consistently shown reductions in external knee-flexion moment and hip-extension moment, whereas external ankle plantar-flexion moments increased immediately after initial contact compared with the contralateral limb and with healthy matched control participants.^16–18 These findings suggest a tendency toward quadriceps avoidance coupled with compensatory adaptations at the hip and ankle. Unfortunately, whereas these compensations may enable completion of the task and potentially a higher level of daily activity, they also represent a substantial deviation from normal movement patterns, which may help to explain why individuals with ACLR are at greater risk for reinjury,¹⁹ contralateral knee injury,^19,20 and development of premature knee-joint OA.²¹Understanding the persistent functional compensation patterns that can be assessed clinically after ACLR is essential for targeting patient-specific treatments and identifying which patients may be at greater risk for subsequent injury. The Landing Error Scoring System (LESS) is a viable clinical tool designed to predict lower extremity injury risk by identifying high-risk movement patterns during a drop-landing task.²² The LESS has mainly been used as a measure of primary knee-injury risk and only recently has been investigated in a predominantly female sample of individuals with ACLR who committed a greater number of errors than healthy matched control participants.²³ In addition, the relation of the LESS to common patient-reported outcome measures and modifiable clinical measurements has not been described in this population. Therefore, the primary purpose of our study was to compare performance on the LESS between participants with ACLR and healthy control participants. We hypothesized that participants with ACLR would have greater LESS scores (ie, more landing errors) than healthy control participants. Our secondary purpose was to quantify the relationship between the LESS score and knee-extension strength, as well as self-reported measures of physical activity, pain, and lower extremity function in participants with ACLR and in healthy participants. We hypothesized that greater LESS scores would be negatively related to deficits in knee-extension strength, physical activity level, and lower extremity function in participants with ACLR.     

Lower extremity proprioceptive sensation in patients with early stage knee osteoarthritis: A comparative study

BackgroundKnee OA causes pain and proprioceptive impairment. The body acts as a closed kinetic chain, and deformation on the knee cannot only affect the knee joint but also can affect the other joints.ObjectiveTo assess the proprioception of lower extremity in early stage knee osteoarthritis compared with without knee osteoarthritis individuals.MethodsThe study sample consisted of 26 adults with early stage knee osteoarthritis and 26 subjects without knee osteoarthritis individuals. Western Ontario and McMaster Universities Osteoarthritis Index was used for clinical disease severity. Visual Analogue Scale was used for pain severity. Proprioception (position and motion sense) was measured by isokinetic dynamometer.ResultsWestern Ontario and McMaster Universities Osteoarthritis Index total score was 10.9 ± 5. Visual Analogue Scale scores during activity were found to be significantly higher than the scores at rest and night for both sides. Hip flexion and internal rotation joint position sense were significantly different between two groups (all p's < 0.05). Hip abduction, knee flexion, ankle and subtalar position sense, as well as hip and knee motion sense were similar between groups (all p's > 0.05). Ankle dorsiflexion and eversion motion sense were significantly different between two groups (all p's < 0.05).ConclusionsThis study demonstrated that the hip flexion and internal rotation position sense and ankle/subtalar joints motion sense may be affected on early stage of knee osteoarthritis. Investigation of the mechanism of proprioception for joints and also focusing on the longitudinal relationship between proprioception, knee OA disease and symptoms is recommended for future studies.     

A Comparison of Psychological Readiness and Patient-Reported Function Between Sexes After Anterior Cruciate Ligament Reconstruction

ContextPostoperative functional and return-to-sport outcomes after anterior cruciate ligament reconstruction (ACLR) differ by sex. However, whether sex disparities are observed in patient-reported outcome measures (PROMs) before return to sport after ACLR is unclear.ObjectivesTo compare common PROMs between young men and women who had not yet returned to sport after ACLR.DesignCross-sectional study.SettingUniversity laboratory.Patients or Other ParticipantsForty-five young men (age = 18.7 ± 2.7 years, time since surgery = 6.8 ± 1.4 months) and 45 women matched for age (±1 year) and time since surgery (±1 month; age = 18.8 ± 2.8 years, time since surgery = 6.9 ± 1.4 months) with ACLR participated.Main Outcome Measure(s)Participants completed the Tegner Activity Scale, ACL Return to Sport After Injury scale, Tampa Scale of Kinesiophobia, International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Score, and Knee Injury and Osteoarthritis Outcome Score (KOOS). The PROMs were compared between men and women using Mann-Whitney U tests. Odds ratios were calculated to evaluate the odds of a male reporting a PROM value above the previously established normative value as compared with a female.ResultsSex differences were present for the IKDC score (P = .01) and KOOS Pain score (P = .04) but not for the Tegner Activity Scale (P = .22), ACL Return to Sport After Injury scale score (P = .78), Tampa Scale of Kinesiophobia score (P = .64), or other KOOS subscales (P values = .40 to .52). The odds of reporting values above normative levels differed only for the IKDC score (odds ratio = 2.72, 95% confidence interval = 1.16, 6.38).ConclusionsAfter ACLR, young men and women reported similar levels of knee-related function, fear of movement, and readiness for return to sport and were equally likely to meet clinically meaningful normative values before return to sport. Overreliance on patient reports or objective functional outcomes in evaluating patient progress and readiness for return to sport after ACLR may limit clinicians in their ability to comprehensively evaluate and develop individualized interventional approaches that optimize patient outcomes.     

Feasibility of a Wearable-Based Physical Activity Goal-Setting Intervention Among Individuals With Anterior Cruciate Ligament Reconstruction

ContextIndividuals with a history of anterior cruciate ligament reconstruction (ACLR) demonstrate persistent reductions in physical activity (PA) volume that are not being addressed during rehabilitation. Currently, it is challenging for clinicians to prescribe exercise interventions that extend beyond in-person rehabilitative care in a manner that is responsive and acceptable to patients.ObjectiveTo investigate the feasibility of using a novel, technology-driven, personalized goal-setting intervention over a 2-month period among young individuals with a history of primary unilateral ACLR.DesignSingle-blinded feasibility study.SettingUniversity communityPatients or Other ParticipantsTen women and 2 men (age = 22.0 ± 3.0 years, time since surgery = 56.0 ± 36.3 months) with a history of primary unilateral ACLR.Intervention(s)All participants completed a 28-day PA observation period immediately followed by a 28-day individualized PA goal-setting intervention period delivered via a commercially available PA monitor.Main Outcome Measure(s)Primary feasibility outcomes were days of PA monitor wear compliance and days of goal achievement during the intervention period. Participants also completed the Knee Osteoarthritis Outcome Score (KOOS) at study enrollment and after the intervention period, and the individual change in the KOOS Quality of Life subscale was compared with the minimal detectable change (7.2 points).ResultsAverage PA monitor wear compliance was 95.5% ± 7.3% during the observation period and 97.7% ± 2.9% during the intervention period. Median goal achievement was 31.5% ± 6.8% during the intervention period. Five participants demonstrated meaningful improvements in the KOOS Quality of Life subscale during the study period.ConclusionsIndividualized goal setting via mobile technology appears to be a feasible approach to PA promotion. However, based on the low rate of daily goal attainment during the intervention period, continued refinement of this intervention aproach would be beneficial before broad clinical implementation.     

Reliability and Validity of a Clinical Assessment Tool for Measuring Scapular Motion in All 3 Anatomical Planes

ContextA single clinical assessment device that can be used to objectively measure scapular motion in each anatomical plane is not currently available. The development of a novel electric goniometer would allow scapular motion in all 3 anatomical planes to be quantified.ObjectiveTo investigate the reliability and validity of an electric goniometer for measuring scapular motion in each anatomical plane during upper extremity elevation.DesignCross-sectional study.SettingLaboratory.Patients or Other ParticipantsSixty participants (29 women, 31 men; age = 30 ± 14 years, height = 1.73 ± 0.10 m, mass = 75.32 ± 16.90 kg) recruited from the general population.Intervention(s)An electric goniometer was used to record clinical measurements of scapular position at rest and total arc of motion (excursion) during active upper extremity elevation in 2 testing sessions separated by several days. Measurements were recorded independently by 2 examiners. In 1 session, scapular motion was recorded simultaneously using a 14-camera, 3-dimensional optical motion-capture system.Main Outcome Measure(s)Reliability analysis included examination of clinical measurements for scapular position at rest and excursion during each condition. Both the intrarater reliability between testing sessions and the interrater reliability recorded in the same session were assessed using intraclass correlation coefficients (ICCs [2,3]). The criterion validity was examined by comparing the mean excursion values of each condition recorded using the electric goniometer and the 3-dimensional optical motion-capture system. Validity was assessed by evaluating the average difference and root mean square error.ResultsThe between-sessions intrarater reliability was moderate to good (ICC [2,3] range = 0.628–0.874). The within-session interrater reliability was moderate to excellent (ICC [2,3] range = 0.545–0.912). The average difference between total excursion values recorded using the electric goniometer and the 3-dimensional optical motion-capture system ranged from −7° to 4°, and the root mean square error ranged from 7° to 10°.ConclusionsThe reliability of scapular measurements was best when a standard operating procedure was used. The electric goniometer provided an accurate measurement of scapular excursions in all 3 anatomical planes during upper extremity elevation.     

Quadriceps Oxygenation During Exercise in Patients With Anterior Cruciate Ligament Reconstruction

ContextThe causes of persistent muscle weakness after anterior cruciate ligament reconstruction (ACLR) are not well known. Changes in muscle oxygenation have been proposed as a possible mechanism.ObjectiveTo investigate changes in quadriceps muscle oxygenation during knee extension in ACLR-involved and ACLR-uninvolved limbs.DesignCase-control study.SettingLaboratory.Patients or Other ParticipantsA total of 20 individuals: 10 patients with primary, unilateral ACLR (7 women, 3 men; age = 22.90 ± 3.45 years, height = 170.81 ± 7.93 cm, mass = 73.7 ± 15.1 kg) and 10 matched control individuals (7 women, 3 men; age = 21.50 ± 2.99 years, height = 170.4 ± 10.7 cm, mass = 68.86 ± 9.51 kg).Intervention(s)Each participant completed a single data-collection session consisting of 5-second isometric contractions at 25%, 50%, and 75% of the volitional maximum followed by a 30-second maximal isometric knee-extension contraction.Main Outcome Measure(s)Oxygenated hemoglobin (O₂Hb) measures in the reconstructed thigh were continuously recorded (versus the uninvolved contralateral limb as well as the nondominant thigh of healthy control individuals) using 3 wearable, wireless near-infrared spectroscopy units placed superficially to the vastus medialis, vastus lateralis, and rectus femoris muscles. Relative changes in oxygenation were ensemble averaged and plotted for each contraction intensity with associated 90% CIs. Statistical significance occurred where portions of the exercise trials with CIs on the O₂Hb graph did not overlap. Effect sizes (Cohen d, 90% CI) were determined for statistical significance.ResultsWe observed less relative change in O₂Hb in patients with ACLR than in healthy control participants in the rectus femoris at 25% (d = 2.1; 90% CI = 1.5, 2.7), 50% (d = 2.8; 90% CI = 2.6, 2.9), and 75% (d = 2.0; 90% CI = 1.9, 2.2) and for the vastus medialis at 75% (d = 1.5; 90% CI = 1.4, 1.5) and 100% (d = 2.6; 90% CI = 2.5, 2.7). Less relative change in O₂Hb was also noted for the vastus medialis in ACLR-involved versus ACLR-uninvolved limbs at 100% (d = 2.62; 90% CI = 2.54, 2.70).ConclusionsQuadriceps muscle oxygenation during exercise differed between patients with ACLR and healthy control individuals. However, not all portions of the quadriceps were affected uniformly across contraction intensities.     

Comparison of Lower Extremity Kinematics and Hip Muscle Activation During Rehabilitation Tasks Between Sexes

Context:

Closed kinetic chain exercises are an integral part of rehabilitation programs after lower extremity injury. Sex differences in lower extremity kinematics have been reported during landing and cutting; however, less is known about sex differences in movement patterns and activation of the hip musculature during common lower extremity rehabilitation exercises.

Objective:

To determine whether lower extremity kinematics and muscle activation levels differ between sexes during closed kinetic chain rehabilitation exercises.

Design:

Cross-sectional with 1 between-subjects factor (sex) and 1 within-subjects factor (exercise).

Setting:

Research laboratory.

Patients or Other Participants:

Participants included 21 women (age  =  23 ± 5.8 years, height  =  167.6 ± 5.1 cm, mass  =  63.7 ± 5.9 kg) and 21 men (age  =  23 ± 4.0 years, height  =  181.4 ± 7.4 cm, mass  =  85.6 ± 16.5 kg).

Intervention(s):

In 1 testing session, participants performed 3 trials each of single-leg squat, lunge, and step-up-and-over exercises.

Main Outcome Measure(s):

We recorded the peak joint angles (degrees) of knee flexion and valgus and hip flexion, extension, adduction, and external rotation for each exercise. We also recorded the electromyographic activity of the gluteus maximus, rectus femoris, adductor longus, and bilateral gluteus medius muscles for the concentric and eccentric phases of each exercise.

Results:

Peak knee flexion angles were smaller and peak hip extension angles were larger for women than for men across all tasks. Peak hip flexion angles during the single-leg squat were smaller for women than for men. Mean root-mean-square amplitudes for the gluteus maximus and rectus femoris muscles in both the concentric and eccentric phases of the 3 exercises were greater for women than for men.

Conclusions:

Sex differences were observed in sagittal-plane movement patterns during the rehabilitation exercises. Because of the sex differences observed in our study, future researchers need to compare the findings for injured participants by sex to garner a better representation of altered kinematic angles and muscle activation levels due to injury.     

Identifying Relationships Among Lower Extremity Alignment Characteristics

Context:

The relationship between lower extremity alignment and lower extremity injury risk remains poorly understood, perhaps because most authors have examined only individual or a select group of alignment variables. Examining the relationships among alignment variables may allow us to more accurately describe lower extremity posture and clarify the relationship between lower extremity alignment and injury risk in future studies.

Objective:

To measure lower extremity alignment variables and examine whether relationships could be identified among these variables.

Design:

Observational study.

Setting:

Laboratory.

Patients or Other Participants:

Two hundred eighteen (102 males: age  =  23.1 ± 3.2 years, height  =  177.3 ± 8.4 cm, mass  =  80.8 ± 13.0 kg; 116 females: age  =  21.8 ± 2.7 years, height  =  163.5 ± 7.4 cm, mass  =  63.4 ± 12.4 kg) healthy, college-aged participants.

Main Outcome Measure(s):

We measured pelvic angle, femoral anteversion, quadriceps angle, tibiofemoral angle, genu recurvatum, and tibial torsion to the nearest degree and navicular drop to the nearest millimeter on the right and left lower extremities. Separate principal components factor analyses were performed for each sex and side (left, right).

Results:

A distinct lower extremity factor was identified, with relationships observed among increased pelvic angle, increased quadriceps angle, and increased tibiofemoral angle. A second distinct lower extremity factor was identified, with relationships observed among increased supine genu recurvatum, decreased tibial torsion, and increased navicular drop. Femoral anteversion loaded as an independent third factor. These distinct lower extremity alignment factors were consistent across side and sex.

Conclusions:

Factor analysis identified 3 distinct lower extremity alignment factors that describe the potential interactions among lower extremity alignment variables. Future authors should examine how these collective alignment variables, both independently and in combination, influence dynamic knee function and risk for lower extremity injuries.     

Jump-Landing Mechanics After Anterior Cruciate Ligament Reconstruction: A Landing Error Scoring System Study

Context:

The Landing Error Scoring System (LESS) is a clinical evaluation of jump-landing mechanics and may provide useful information in assisting with return-to-sport decisions in patients after anterior cruciate ligament reconstruction (ACLR). However, it is currently unknown how patients with ACLR perform on the LESS compared with healthy controls.

Objective:

To determine if the total LESS score differed between individuals with ACLR and healthy controls and to determine the types of errors that differ between groups.

Design:

Cross-sectional study.

Setting:

Research laboratory.

Patients or Other Participants:

A total of 27 individuals with unilateral ACLR (age = 19.8 ± 1.8 years, height = 170 ± 5.5 cm, mass = 68.8 ± 11.9 kg) and 27 controls (age = 20.5 ± 1.7 years, height = 169 ± 8.4 cm, mass = 66.6 ± 9.0 kg) with no history of ACLR.

Intervention(s):

Each participant completed 3 trials of a standardized jump-landing task.

Main Outcome Measure(s):

Each jump landing was assessed for specific postures using standardized LESS criteria by a blinded evaluator. Individual LESS items were summed to create a total LESS score. The dominant limb was assessed in the control group, and the reconstructed limb was assessed in the ACLR group.

Results:

The ACLR group had higher LESS scores compared with controls (ACLR: 6.7 ± 2.1 errors, control: 5.6 ± 1.5 errors, P = .04). Additionally, the ACLR group was more likely to err when landing with lateral trunk flexion (Fisher exact test, P = .002).

Conclusions:

Individuals with ACLR had worse landing mechanics as measured by the LESS. Lateral trunk deviation may be related to quadriceps avoidance in the reconstructed limb or poor trunk neuromuscular control. The LESS is useful for evaluating landing errors in patients with ACLR and may help to identify areas of focus during rehabilitation and before return to sport.Key Words: musculoskeletal injuries, jump landing, trunk, core neuromuscular control

Key Points

• Individuals with anterior cruciate ligament reconstruction had higher Landing Error Scoring System scores (ie, worse landing mechanics) than the control group.
• Errors in the Landing Error Scoring System were most common for lateral trunk flexion away from the reconstructed limb in patients after anterior cruciate ligament reconstruction.

Second anterior cruciate ligament (ACL) injury rates range from 12% to 26% and include injury to both the ipsilateral (graft failure or retear) and contralateral ACL.^1–3 When compared with the general population, rates for these injuries are highest in individuals who return to sport and participate in high-risk activities.^1–3 In fact, individuals with prior ACL injury and reconstruction are 15 times more likely to suffer a second ACL injury than those with no history of ACL rupture.³ Paterno et al⁴ illustrated this point by tracking individuals with ACL reconstruction (ACLR) for 1 year after return to sport. Thirteen of 56 athletes (23%) who returned to cutting and pivoting sports suffered a second ACL injury (10 contralateral, 3 ipsilateral). This elucidates the difficulty in safely returning patients to activity, as all had completed a rehabilitation program and were cleared by their health care providers to return to sport. Most return-to-activity guidelines are based on time from surgery, stability of the graft, and functional ability rather than biomechanical movement patterns that have been shown to increase an individual''s risk for ACL injury.^4–6Lower extremity kinematics and kinetics differ between individuals with ACLR and healthy controls when examined using 3-dimensional motion analysis.^7–9 Delahunt et al⁸ compared kinematics during a drop vertical jump in 14 females with ACLR (average of 4.4 years after surgical reconstruction) with healthy controls. The reconstructed group had greater peak hip- and knee-adduction angles, greater hip internal-rotation angles, and decreased peak knee-flexion angles.⁸ Additionally, female soccer players with ACLR have been reported to exhibit greater knee-abduction angles and adductor moment during a side-step cutting maneuver than healthy controls.⁷ Furthermore, patients with reconstructions landed with greater force on the healthy limb compared with the reconstructed limb.¹⁰ Together, these studies establish that individuals with ACLR have movement strategies that may be partially responsible for high second-injury rates in this population.The purpose of rehabilitation after ACLR depends on the goals of each patient. In adolescents, in whom ACLR is common, patients often have the goal of returning to sport. Current guidelines dictate that a patient''s reconstructed extremity be greater than 90% of the reference limb during clinical testing. These tests often encompass a variety of factors associated with performance, such as quadriceps and hamstrings strength and hop tests. Oftentimes, performance on these tests is based on a single factor, such as the time to completion or distance travelled. Although these metrics are important, how an individual moves during these activities should also be examined. Evaluating the quality of motion may provide clinicians with useful information about neuromuscular control during high-risk activities that can be addressed during the rehabilitation process and can also be part of the return-to-sport decision criteria.One of the most researched tools available to evaluate quality of motion during landing is the Landing Error Scoring System (LESS). The LESS evaluates 17 items or errors related to landing position that are associated with ACL loading.¹¹ Errors are summed, with a higher score theoretically associated with a higher risk of injury. The LESS has good to excellent interrater and intrarater reliability and has been validated against 3-dimensional motion analysis.^11,12 Females have worse (higher) LESS scores than males,^11,13 and the types of errors differ between sexes. Females are more likely to have poor landing technique, with less hip and knee flexion at initial contact, increased knee valgus with a wide stance, and decreased knee-flexion displacement.¹³ Males are more likely to commit errors during landing due to toeing out, landing heels first, and landing with an asymmetrical foot position.¹³ The LESS score can be improved using prepractice injury-prevention programs.¹⁴ Previous researchers have focused only on healthy individuals with no history of injury, and given the elevated risk of injury in those with ACLR,⁴ the LESS may be useful for evaluating movement mechanics and assisting with return-to-sport decision making. It is currently unknown if individuals with ACLR perform differently on the LESS or exhibit different errors on specific LESS items than healthy controls.Therefore, the purpose of our investigation was to determine if total LESS scores differed between individuals with ACLR and healthy controls. A second purpose was to determine if the frequencies of errors for each LESS item differed between groups. We hypothesized that the ACLR group would have a higher total LESS score compared with healthy controls and that item-specific errors would be more frequently observed in the ACLR group.     

Factors Associated With Energy Expenditure and Energy Balance in Acute Sport-Related Concussion

ContextSport-related concussion (SRC) is characterized by a pathologic neurometabolic cascade that results in an increased intracranial energy demand and a decreased energy supply. Little is known about the whole-body energy-related effects of SRC.ObjectiveTo examine factors associated with whole-body resting metabolic rate (RMR), total energy expenditure (TEE), energy consumption (EC), and energy balance (EBal) in student-athletes acutely after SRC and healthy matched control individuals.DesignCase-control study.SettingUniversity research laboratory.Patients or Other ParticipantsStudent-athletes diagnosed with SRC (n = 28, 50% female, age = 18.4 ± 1.8 years, body mass index [BMI] = 24.1 ± 4.1 kg/m²) assessed ≤72 hours postinjury and a matched control group (n = 28, 50% female, age = 19.4 ± 2.9 years, BMI = 24.7 ± 4.78 kg/m²).Main Outcome Measure(s)Resting metabolic rate was measured via indirect calorimetry. Participants reported their physical activity and dietary intake for 3 days, which we used to estimate TEE and EC, respectively, and to calculate EBal (EC:TEE ratio). Resting metabolic rate, TEE, and EC were normalized to body mass. Group and group-by-sex comparisons were conducted for RMR·kg⁻¹, TEE·kg⁻¹, EC·kg⁻¹, and EBal using independent t tests with the a priori α = .05. Associations of age, sex, concussion history, BMI, and symptom burden with RMR·kg⁻¹ and EBal were explored with linear regression models.ResultsTotal energy expenditure·kg⁻¹ was lower (P < .01; mean difference ± SD = −5.31 ± 1.41 kcal·kg⁻¹) and EBal was higher (P < .01; 0.28 ± 0.10) in SRC participants than in control participants. Both sexes with SRC had lower TEE·kg⁻¹ than did the control participants (P values ≤ .04); females with SRC had higher EBal than controls (P = .01), but male groups did not differ. Higher RMR·kg⁻¹ was associated with history of concussion (adjusted R² = .10, β = 0.65). Younger age (β = −0.35), fewer concussions (β = −0.35), lower BMI (β = −0.32), greater symptom duration (β = 1.50), and lower symptom severity (β = −1.59) were associated with higher EBal (adjusted R² = .54).ConclusionsTotal energy expenditure·kg⁻¹ and EBal appeared to be affected by acute SRC, despite no differences in RMR·kg⁻¹. Sex, concussion history, BMI, and symptom burden were associated with acute energy-related outcomes.     

Influence of age on dynamic position sense: evidence using a sequential movement task

Age related changes to the nervous system are well documented. The main objectives of this study were to examine age-associated changes in dynamic position sense and relate these changes to measures of balance and physical function. Two groups of individuals (young <30 years; elderly >60 years) performed an upper extremity movement sequence triggered by a pre-determined target angle during passive rotations of the ankle joint at ten random velocities (10–90° s^–1). Balance was assessed with a series of timed standing tests. Physical function was assessed with the SF 36 questionnaire. Muscle activity was recorded from the ankle dorsiflexors and plantarflexors during the dynamic position tests. Increased error in the elderly group suggested that dynamic position sense declines with age. Moreover, this decline in dynamic position sense was associated with decreased balance and an impaired perception of physical function. The elderly also co-contracted the ankle plantarflexors and dorsiflexors during the proprioceptive testing, perhaps as a strategy to gain up spindle sensitivity. These findings suggest that impaired dynamic position sense of the ankle contributes to alterations in the overall physical function and balance in the elderly. Rehabilitative training methods that improve dynamic position sense of the ankles may improve physical function and balance in the elderly.     

Effectiveness of a Low-Calorie Weight Loss Program in Moderately and Severely Obese Patients

AimsTo compare effectiveness of a 1-year weight loss program in moderately and severely obese patients.MethodsThe study sample included 311 obese patients participating in a weight loss program, which comprised a 12-week weight reduction phase (low-calorie formula diet) and a 40-week weight maintenance phase. Body weight and glucose and lipid values were determined at the beginning of the program as well as after the weight reduction and the weight maintenance phase. Participants were analyzed according to their BMI class at baseline (30-34.9 kg/m²; 35-39.9 kg/m²; 40-44.9 kg/m²; 45-49.9 kg/m²; ≥50 kg/m²). Furthermore, moderately obese patients (BMI ℋ 40 kg/m²) were compared to severely obese participants (BMI ≥ 40 kg/m²).ResultsOut of 311 participants, 217 individuals completed the program. Their mean baseline BMI was 41.8 ± 0.5 kg/m². Average weight loss was 17.9 ± 0.6%, resulting in a BMI of 34.3 ± 0.4 kg/m² after 1 year (p ℋ 0.001). Overall weight loss was not significantly different in moderately and severely obese participants. Yet, severely obese participants achieved greater weight loss during the weight maintenance phase than moderately obese participants (−3.1 ± 0.7% vs. −1.2 ± 0.6%; p = 0.04). Improvements in lipid profiles and glucose metabolism were found throughout all BMI classes.Conclusion1-year weight loss intervention improves body weight as well as lipid and glucose metabolism not only in moderately, but also in severely obese individuals.Key Words: Weight loss, Weight maintenance, Weight regain, Obesity, Low calorie diet, Formula diet, Diabetes conversion     

Cooling Capacity of Transpulmonary Cooling and Cold-Water Immersion After Exercise-Induced Hyperthermia

ContextCold-water immersion (CWI) may not be feasible in some remote settings, prompting the identification of alternative cooling methods as adjunct treatment modalities for exertional heat stroke (EHS).ObjectiveTo determine the differences in cooling capacities between CWI and the inhalation of cooled air.DesignRandomized controlled clinical trial.SettingLaboratory.Patients or Other ParticipantsA total of 12 recreationally active participants (7 men, 5 women; age = 26 ± 4 years, height = 170.6 ± 10.1 cm, mass = 76.0 ± 18.0 kg, body fat = 18.5% ± 9.7%, peak oxygen uptake = 42.7 ± 8.9 mL·kg⁻¹·min⁻¹).Intervention(s)After exercise in a hot environment (40°C and 40% relative humidity), participants were randomized to 3 cooling conditions: cooling during passive rest (PASS; control), CWI, and the Polar Breeze thermal rehabilitation machine (PB) with which participants inspired cooled air (22.2°C ± 1.0°C).Main Outcome Measure(s)Rectal temperature (T_REC) and heart rate were continuously measured throughout cooling until T_REC reached 38.25°C.ResultsCooling rates during CWI (0.18°C·min⁻¹ ± 0.06°C·min⁻¹) were greater than those during PASS (mean difference [95% CI] of 0.16°C·min⁻¹ [0.13°C·min⁻¹, 0.19°C·min⁻¹]; P < .001) and PB (0.15°C·min⁻¹ [0.12°C·min⁻¹, 0.16°C·min⁻¹]; P < .001). Elapsed time to reach a T_REC of 38.25°C was also faster with CWI (9.71 ± 3.30 minutes) than PASS (−58.1 minutes [−77.1, −39.9 minutes]; P < .001) and PB (−46.8 minutes [−65.5, −28.2 minutes]; P < .001). Differences in cooling rates and time to reach a T_REC of 38.25°C between PASS and PB were not different (P > .05).ConclusionsTranspulmonary cooling via cooled-air inhalation did not promote an optimal cooling rate (>0.15°C·min⁻¹) for the successful treatment of EHS. In remote settings where EHS is a risk, access and use of treatment methods via CWI or cold-water dousing are imperative to ensuring survival.Trial RegistryClinicalTrials.gov (NCT0419026).     

Increased Contact Time and Strength Deficits in Runners With Exercise-Related Lower Leg Pain

ContextExercise-related lower leg pain (ERLLP) is common in runners.ObjectiveTo compare biomechanical (kinematic, kinetic, and spatiotemporal) measures obtained from wearable sensors as well as lower extremity alignment, range of motion, and strength during running between runners with and those without ERLLP.DesignCase-control study.SettingField and laboratory.Patients or Other ParticipantsOf 32 young adults who had been running regularly (>10 mi [16 km] per week) for ≥3 months, 16 had ERLLP for ≥2 weeks and 16 were healthy control participants.Main Outcome Measure(s)Both field and laboratory measures were collected at the initial visit. The laboratory measures consisted of alignment (arch height index, foot posture index, navicular drop, tibial torsion, Q-angle, and hip anteversion), range of motion (great toe, ankle, knee, and hip), and strength. Participants then completed a 1.67-mi (2.69-km) run along a predetermined route to calibrate the RunScribe devices. The RunScribe wearable sensors collected kinematic (pronation excursion and maximum pronation velocity), kinetic (impact g and braking g), and spatiotemporal (stride length, step length, contact time, stride pace, and flight ratio) measures. Participants then wore the sensors during at least 3 training runs in the next week.ResultsThe ERLLP group had a slower stride pace than the healthy group, which was accounted for as a covariate in subsequent analyses. The ERLLP group had a longer contact time during the stance phase of running (mean difference [MD] = 18.00 ± 8.27 milliseconds) and decreased stride length (MD = −0.11 ± 0.05 m) than the control group. For the clinical measures, the ERLLP group demonstrated increased range of motion for great-toe flexion (MD = 13.9 ± 4.6°) and ankle eversion (MD = 6.3 ± 2.7°) and decreased strength for ankle inversion (MD = −0.49 ± 0.23 N/kg), ankle eversion (MD = −0.57 ± 0.27 N/kg), and hip flexion (MD = −0.99 ± 0.39 N/kg).ConclusionsThe ERLLP group exhibited a longer contact time and decreased stride length during running as well as strength deficits at the ankle and hip. Gait retraining and lower extremity strengthening may be warranted as clinical interventions in runners with ERLLP.