Efficacy of ACL injury risk screening methods in identifying high‐risk landing patterns during a sport‐specific task

Screening methods sensitive to movement strategies that increase anterior cruciate ligament (ACL) loads are likely to be effective in identifying athletes at‐risk of ACL injury. Current ACL injury risk screening methods are yet to be evaluated for their ability to identify athletes' who exhibit high‐risk lower limb mechanics during sport‐specific maneuvers associated with ACL injury occurrences. The purpose of this study was to examine the efficacy of two ACL injury risk screening methods in identifying high‐risk lower limb mechanics during a sport‐specific landing task. Thirty‐two female athletes were screened using the Landing Error Scoring System (LESS) and Tuck Jump Assessment. Participants' also completed a sport‐specific landing task, during which three‐dimensional kinematic and kinetic data were collected. One‐dimensional statistical parametric mapping was used to examine the relationships between screening method scores, and the three‐dimensional hip and knee joint rotation and moment data from the sport‐specific landing. Higher LESS scores were associated with reduced knee flexion from 30 to 57 ms after initial contact (P = 0.003) during the sport‐specific landing; however, no additional relationships were found. These findings suggest the LESS and Tuck Jump Assessment may have minimal applicability in identifying athletes' who exhibit high‐risk landing postures in the sport‐specific task examined.     

Patellofemoral joint loading during the forward and backward lunge

ObjectiveTo examine patellofemoral joint (PFJ) loading in two lunge movements: Forward Lunge (FL) and Backward Lunge (BL).DesignRepeated Measures.SettingUniversity Biomechanics Laboratory.Participants20 asymptomatic females.Main outcome measuresSix trials of two lunge movements (FL and BL) to a depth of 75% of leg length were performed. 3-D motion capture and force platforms were used to collect data as input into a musculoskeletal model to determine quadriceps force, PFJ reaction force, PFJ stress, and knee flexion angle.ResultsMultivariate analysis indicated differences in PFJ loading variables and joint angles between the lunge movements (Forward vs. Backward) and phases (Down vs. Up). Quadriceps force, PFJ reaction force, and knee flexion angle were larger in the FL movement and Up phases. PFJ loading rate was greater in the FL movement along with a lower forward trunk tilt.ConclusionThe FL produced greater PFJ loading variables compared to the BL. Further research is needed to examine a population of individuals who have patellofemoral pain (PFP) to see if their symptoms may be reduced when using the BL.     

Reduction of risk factors for ACL Re-injuries using an innovative biofeedback approach: A phase I randomized clinical trial

ObjectivesDetermine the safety and initial efficacy of a novel biofeedback intervention to improve landing mechanics in patients following anterior cruciate ligament reconstruction (ACLR).MethodsForty patients post-ACLR (age: 16.9 ± 2.0 years) were randomly allocated to a biofeedback intervention or an attention control group. Patients in the biofeedback group completed 12 sessions over six-weeks that included bilateral unweighted squats with visual and tactile biofeedback. Patients in the control group completed a six-week educational program. Lower extremity mechanics were collected during a bilateral stop jump at baseline, six-weeks, and 12-weeks post-intervention. Linear mixed-effects models adjusted for sex and graft type determined the main effects of and interactions between group and time.ResultsNo group by time interaction existed for peak knee extension moment symmetry. A group by time interaction existed for peak vertical ground reaction force symmetry (p = 0.012), where patients in the biofeedback group had greater improvements in symmetry between baseline and post-intervention that were not maintained through the retention assessments.ConclusionThis novel biofeedback program did not reduce risk factors for second ACL injuries. Future work could develop and test multidisciplinary interventions for reducing second ACL injury risk factors.Clinicaltrials.gov identifier(NCT03273673)     

Reliability of a field-based drop vertical jump screening test for ACL injury risk assessment

Objectives: There is an epidemic of anterior cruciate ligament (ACL) injuries in youth athletes. Poor neuromuscular control is an easily modifiable risk factor for ACL injury, and can be screened for by observing dynamic knee valgus on landing in a drop vertical jump test. This study aims to validate a simple, clinically useful population-based screening test to identify at-risk athletes prior to participation in organized sports. We hypothesized that both physicians and allied health professionals would be accurate in subjectively assessing injury risk in real-time field and office conditions without motion analysis data and would be in agreement with each other. Methods: We evaluated the inter-rater reliability of risk assessment by various observer groups, including physicians and allied health professionals, commonly involved in the care of youth athletes. Fifteen athletes age 11–17 were filmed performing a drop vertical jump test. These videos were viewed by 242 observers including orthopaedic surgeons, orthopaedic residents/fellows, coaches, athletic trainers (ATCs), and physical therapists (PTs), with the observer asked to subjectively estimate the risk level of each jumper. Objective injury risk was calculated using normalized knee separation distance (measured using Dartfish, Alpharetta, GA), based on previously published studies. Risk assessments by observers were compared to each other to determine inter-rater reliability, and to the objectively calculated risk level to determine sensitivity and specificity. Seventy one observers repeated the test at a minimum of 6 weeks later to determine intra-rater reliability. Results: Between groups, the inter-rater reliability was high, κ = 0.92 (95% CI 0.829–0.969, p < 0.05), indicating that no single group gave better (or worse) assessments, including comparisons between physicians and allied health professionals. With a screening cutoff isolated to subjects identified by observers as “high risk”, the sensitivity was 63.06% and specificity 82.81%. Reducing the screening cutoff to also include jumpers identified as “medium risk” increased sensitivity to 95.04% and decreased the specificity to 46.07%. Intra-rater reliability was moderate, κ = 0.55 (95% CI 0.49–0.61, p < 0.05), indicating that individual observers made reproducible risk assessments. Conclusions: This study supports the use of a simple, field-based observational drop vertical jump screening test to identify athletes at risk for ACL injury. Our study shows good inter- and intra-rater reliability and high sensitivity and suggests that screening can be performed without significant training by physicians as well as allied health professionals, including: coaches, athletic trainers and physical therapists. Identification of these high-risk athletes may play a role in enrollment in appropriate preventative neuromuscular training programs, which have been shown to decrease the incidence of ACL injuries in this population.     

The drill wobble effect: oversizing the femoral tunnel during ACL reconstruction

Objectives: In ACL reconstruction, autologous tendon graft can be attached to the femur, within a boney tunnel, using an Endobutton device. The ultimate aim being to achieve biological fixation and incorporation into the bone. Accurate bone tunnel diameter to match the tendon graft is vital to biologic incorporation and strength. The common technique of in sequence passing a guide wire, a cannulated 4.5 mm Endobutton drill, then a cannulated femoral socket drill causes the guidewire to lose cortical fixation and stability before the femoral socket drill is passed.

The Objective of this study is to analyze this common technique of femoral socket creation and determine if it results in unintentionally oversizing the femoral socket due to femoral socket drill-wobble over a destabilised guide wire.

Methods: 12 cadaveric femoral pairs equally divided between two groups underwent femoral socket creation in one of the two following sequences.

Group 1: Guidewire, 4.5 mm endobutton drill, 8 mm femoral socket drill. Group 2: Guidewire, 8 mm femoral socket drill, 4.5 mm endobutton drill. The created femoral tunnels apertures and calibres were measured and then compared for accuracy between the two groups.

Results: Passing the 4.5 mm drill before the 8 mm socket drill results in oversized tunnel apertures and calibres when compared to passing an 8 mm socket drill after the 4.5 mm drill has been passed (p<0.0001).

Conclusion: To most precisely create an 8 mm femoral socket in ACL reconstruction, the 8 mm femoral socket reamer followed by the 4.5 mm should be passed over the guide wire to prevent guide wire destabilization and drill-wobble.     

A glass foreign body in the knee joint mistaken for ACL avulsion: an unusual case

Foreign body in the knee is associated with trauma to knee or deliberate self harm. We see them often in clinical practice. They come in all forms and shapes. Very rarely one can find a foreign body within a joint without obvious external scarring (e.g. needle). We have not come across anywhere in the literature of a large foreign body in the knee joint without a definitive history of injury where the external scar has healed so well to become inconspicuous. With this background it is even more difficult when the X-rays mimic anterior cruciate ligament (ACL) avulsion. This case report highlights the fact that diagnosis of a foreign body in the knee joint can sometimes be challenging and almost impossible when there is no history of any injury and when the X-ray mimics ACL avulsion.     

Joint power and kinematics coordination in load carriage running: Implications for performance and injury

Investigating the impact of incremental load magnitude on running joint power and kinematics is important for understanding the energy cost burden and potential injury-causative mechanisms associated with load carriage. It was hypothesized that incremental load magnitude would result in phase-specific, joint power and kinematic changes within the stance phase of running, and that these relationships would vary at different running velocities. Thirty-one participants performed running while carrying three load magnitudes (0%, 10%, 20% body weight), at three velocities (3, 4, 5 m/s). Lower limb trajectories and ground reaction forces were captured, and global optimization was used to derive the variables. The relationships between load magnitude and joint power and angle vectors, at each running velocity, were analyzed using Statistical Parametric Mapping Canonical Correlation Analysis. Incremental load magnitude was positively correlated to joint power in the second half of stance. Increasing load magnitude was also positively correlated with alterations in three dimensional ankle angles during mid-stance (4.0 and 5.0 m/s), knee angles at mid-stance (at 5.0 m/s), and hip angles during toe-off (at all velocities). Post hoc analyses indicated that at faster running velocities (4.0 and 5.0 m/s), increasing load magnitude appeared to alter power contribution in a distal-to-proximal (ankle → hip) joint sequence from mid-stance to toe-off. In addition, kinematic changes due to increasing load influenced both sagittal and non-sagittal plane lower limb joint angles. This study provides a list of plausible factors that may influence running energy cost and injury risk during load carriage running.     

ACL injury risk in elite female youth soccer: Changes in neuromuscular control of the knee following soccer‐specific fatigue

Fatigue is known to influence dynamic knee joint stability from a neuromuscular perspective, and electromechanical delay (EMD) plays an important role as the feedback activation mechanism that stabilizes the joint. The aim of this study was to investigate the influence of soccer‐specific fatigue on EMD in U13‐, U15‐, and U17‐year‐old female soccer players. Thirty‐six youth soccer players performed eccentric actions of the hamstrings in a prone position at 60, 120, and 180°/s before and after a soccer‐specific fatigue trial. Surface electromyography was used to determine EMD from the semitendinosus, biceps femoris and gastrocnemius. A time × age × muscle × velocity repeated measures analysis of variance was used to explore the influence of fatigue on EMD. A significant main effect for time (P = 0.001) indicated that EMD was significantly longer post‐ compared with pre‐fatigue (58.4% increase). A significant time × group interaction effect (P = 0.046) indicated EMD was significantly longer in the U13 age group compared with the U15 (P = 0.011) and U17 (P = 0.021) groups and greater post‐fatigue. Soccer‐specific fatigue compromised neuromuscular feedback mechanisms and the age‐related effects may represent a more compliant muscle‐tendon system in younger compared with older girls, increasing risk of injury.     

Electromechanical delay of the knee extensor muscles is not altered after harvesting the patellar tendon as a graft for ACL reconstruction: implications for sports performance

Although the scar tissue, which heals the donor site defect, has different elasticity from the neighbouring patellar tissue, it remains unclear if this scar tissue can lead to the changes of the electromechanical delay (EMD) of the knee extensor muscles. If such changes do exist, they can possibly affect both the utilization of the stored energy in the series elastic component, as well as the optimal performance of the knee joint movement. The purpose of this study was to investigate the influence of harvesting the patellar tendon during anterior cruciate ligament (ACL) reconstruction and the associated patellar tendon scar tissue development on the EMD of the rectus femoris (RF) and vastus medialis (VM) muscles. Seventeen patients who underwent an ACL reconstruction using the medial third of the patellar tendon were divided in two groups based upon their post-operative time interval. Maximal voluntary contraction from the knee extensors, surface EMG activity, and ultrasonographic measurements of the patellar tendon cross-section area were obtained from both knees. Our results revealed that no significant changes for the maximal voluntary contraction of the knee extensors and for the EMD of the RF and the VM muscles due to patellar scar tissue development after harvesting the tendon for ACL reconstruction. The EMD, as a component of the stretch reflex, is important for the utilization of the stored energy in the series elastic component and thus, optimal sports performance. However, from our results, it can be implied that the ACL reconstruction using a patellar tendon graft would not impair sports performance as far as EMD is concerned.     

Comparative and morphological analysis of commonly used autografts for anterior cruciate ligament reconstruction with the native ACL: an electron,microscopic and morphologic study

Ligaments and tendons are similar in composition but differ in proportion and arrangement. Tendons are being used as grafts for the ACL reconstruction. Their microscopic structure has not been sufficiently studied and compared to the native ACL. A null hypothesis was declared stating that the anterior cruciate ligament should be histological, morphologically and functionally different from the tendon grafts used for ACL reconstruction. We investigated similarities and differences of the structure of ACL and tendons used as a graft tissue for ACL reconstruction. In this study, standardized samples of quadriceps, hamstrings (semitendinosus and gracilis) and patellar tendons, and the ACL were harvested from 26 autopsies (average age 36.4) and were investigated using light and electron microscopy, immunohistochemistry and morphometry. The thickness of the collagen fibrils, collagen organization and diameter, the fibril/interstitium ratio, density of fibroblasts and blood vessels, and distribution of the collagen type I, III and V fibrils were analyzed. The semitendinosus showed the highest density of fibroblasts and blood vessels, while the gracilis the highest fibril/interstitium ratio. No differences regarding the thickness of collagen fibrils and distribution of fibrils were found. The ACL had the highest concentration of type III and V collagen fibrils as well as elastic fibers. The histological and ultrastructural appearance of the ACL differs from those of the tendons used as graft, for ACL reconstruction. Its ultrastructure is varied and complex, with its collagen fibers bundles lying in many directions.     

New understanding of the complex structure of knee menisci: Implications for injury risk and repair potential for athletes

Menisci help maintain the structural integrity of the knee. However, the poor healing potential of the meniscus following a knee injury can not only end a career in sports but lead to osteoarthritis later in life. Complete understanding of meniscal structure is essential for evaluating its risk for injury and subsequent successful repair. This study used novel approaches to elucidate meniscal architecture. The radial and circumferential collagen fibrils in the meniscus were investigated using novel tissue‐preparative techniques for light and electron microscopic studies. The results demonstrate a unique architecture based on differences in the packaging of the fundamental collagen fibrils. For radial arrays, the collagen fibrils are arranged in parallel into ～10 μm bundles, which associate laterally to form flat sheets of varying dimensions that bifurcate and come together to form a honeycomb network within the body of the meniscus. In contrast, the circumferential arrays display a complex network of collagen fibrils arranged into ～5 μm bundles. Interestingly, both types of architectural organization of collagen fibrils in meniscus are conserved across mammalian species and are age and sex independent. These findings imply that disruptions in meniscal architecture following an injury contribute to poor prognosis for functional repair.     

Ski and snowboard school programs: Injury surveillance and risk factors for grade‐specific injury

The objective of our study was to evaluate incidence rates and profile of school program ski and snowboard‐related injuries by school grade group using a historical cohort design. Injuries were identified via Accident Report Forms completed by ski patrollers. Severe injury was defined as those with ambulance evacuation or recommending patient transport to hospital. Poisson regression analysis was used to examine the school grade group‐specific injury rates adjusting for risk factors (sex, activity, ability, and socioeconomic status) and accounting for the effect of clustering by school. Forty of 107 (37%) injuries reported were severe. Adolescents (grades 7‐12) had higher crude injury rates (91 of 10 000 student‐days) than children (grades 1‐3: 25 of 10 000 student‐days; grades 4‐6: 65 of 10 000 student‐days). Those in grades 1‐3 had no severe injuries. Although the rate of injury was lower in grades 1‐3, there were no statistically significant grade group differences in adjusted analyses. Snowboarders had a higher rate of injury compared with skiers, while higher ability level was protective. Participants in grades 1‐3 had the lowest crude and adjusted injury rates. Students in grades 7‐12 had the highest rate of overall and severe injuries. These results will inform evidence‐based guidelines for school ski/snowboard program participation by school‐aged children.     

Knee and hip loading patterns at different phases in the menstrual cycle: implications for the gender difference in anterior cruciate ligament injury rates

BACKGROUND: Menstrual cycle phase has been correlated with risk of noncontact anterior cruciate ligament injury in women. The mechanism by which hormonal cycling may affect injury rate is unknown. HYPOTHESES: Jumping and landing activities performed during different phases of the menstrual cycle lead to differences in foot strike knee flexion, as well as peak knee and hip loads, in women not taking an oral contraceptive but not in women taking an oral contraceptive. Women will experience greater normalized joint loads than men during these activities. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty-five women (13 using oral contraceptives) and 12 men performed repeated trials of a horizontal jump, vertical jump, and drop from a 30-cm box on the left leg. Lower limb kinematics (foot strike knee flexion) and peak externally applied moments were calculated (hip adduction moment, hip internal rotation moment, knee flexion moment, knee abduction moment). Men were tested once. Women were tested twice for each phase of the menstrual cycle (follicular, luteal, ovulatory), as determined from serum analysis. An analysis of variance was used to examine differences between phases of the menstrual cycle and between groups (alpha = .05). RESULTS: No significant differences in moments or knee angle were observed between phases in either female group or between the 2 female groups or between either female group and the male controls. CONCLUSIONS: Variations of the menstrual cycle and the use of an oral contraceptive do not affect knee or hip joint loading during jumping and landing tasks. CLINICAL RELEVANCE: Because knee and hip joint loading is unaffected by cyclic variations in hormone levels, the observed difference in injury rates is more likely attributable to persistent differences in strength, neuromuscular coordination, or ligament properties.     

Drill design using the ’control-chaos continuum’: Blending science and art during return to sport following knee injury in elite football

Establishing the level of risk, planning and adapting the return to sport (RTS) process following a complex knee injury involves drawing on a combination of relevant high-quality evidence and practitioner experience. On-pitch rehabilitation is a critical element of this process, providing an effective transition from rehabilitation to team training. The ‘control-chaos continuum’ (CCC) is an adaptable framework for on-pitch rehabilitation moving from high control to high chaos, progressively increasing running load demands and incorporating greater perceptual and neurocognitive challenges within sport-specific drills. Drills are a key element of the CCC, and are designed to ensure specificity, ecological validity and maintaining player interest. We showcase drill progression through the phases of the CCC, highlighting the use of constraints to create drills that incorporate the physical, technical, tactical and injury-specific needs of the player. We also provide recommendations to help practitioners create training session content using the CCC to help replicate the demands of team training within their own environment.     

Embolisation with Guglielmi detachable coils during the period of increased risk for cerebral vasospasm: early outcome

In a retrospective study, we investigated whether embolisation of intracranial aneurysms during the spasm period (days 3–14) after subarachnoid haemorrhage carries an increased risk. A comparison was made with patients embolised during the same period but in the first 2 days after the haemorrhage. The two groups compared well except for a higher incidence of posterior circulation aneurysm in the group with delayed treatment. There seems to be no difference in the short-term outcome between the two. Received: 30 April 1999 Accepted: 3 March 2000