Associations between Distance and Loading Symmetry during Return to Sport Hop Testing

Anterior Cruciate Ligament Return to Play: "A Framework for Decision Making"

Anterior cruciate ligament (ACL) injury is common in athletic individuals and often leads to physical impairments, a low rate of return to performance, reinjuries, and sometimes reductions in career length [...].

Anterior Cruciate Ligament Reconstruction Return to Sport Testing Passing Rates for Healthy People: A Systematic Review

BACKGROUND

Return to sport (RTS) is a common goal after anterior cruciate ligament (ACL) reconstruction (ACLR) but carries a relatively high risk of reinjury with up to 20% to 25% of athletes experiencing graft rupture or contralateral ACL tear. While there is increased emphasis on establishing safe RTS criteria for athletes to return to previous activity levels, studies show that even healthy individuals have difficulty passing RTS testing.

PURPOSE

To synthesize data concerning whether healthy individuals can pass ACLR RTS rehabilitation tests.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

Following the established PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, the authors conducted a systematic literature search in May 2023. Three databases were used in the search (PubMed, EMBASE, and SPORTDiscus) to retrieve all studies that conducted ACLR RTS rehabilitation tests on healthy individuals. Tests included were isometric strength, isokinetic strength, hop, and balance tests. The search was performed in duplicate, and a quality assessment of all studies was included.

RESULTS

A total of 1724 studies were retrieved, of which 32 were included, involving 1552 controls with no history of ACL injury. From the studies analyzed, 5.3% to 42.2% of healthy participants failed 6 different hop tests, 15.2% failed the Star Excursion Balance Test, 37% failed the isometric knee flexion test, 50% failed the isometric knee extension test, and 23.7% to 28.9% failed the drop vertical jump test. An asymmetry index ≥10% was found in 6 of the 18 isokinetic tests and 2 of the 14 isometric tests. Hop testing was the most common test in the included studies (56.3%), followed by balance testing (31.3%), isometric strength testing (31.3%), isokinetic strength testing (25%), and drop vertical jump (6.3%).

CONCLUSION

Many healthy individuals fail ACLR RTS tests, with some having an inherent variation from side to side that is >10%. The passing threshold for RTS testing should be a value that is practical yet helps reduce reinjury rates.

Sensor-based technologies for motion analysis in sports injuries: a scoping review

BACKGROUND

Insightful motion analysis provides valuable information for athlete health, a crucial aspect of sports medicine. This systematic review presents an analytical overview of the use of various sensors in motion analysis for sports injury assessment.

METHODS

A comprehensive search of PubMed/MEDLINE, Scopus, and Web of Science was conducted in February 2024 using search terms related to "sport", "athlete", "sensor-based technology", "motion analysis", and "injury." Studies were included based on PCC (Participants, Concept, Context) criteria. Key data, including sensor types, motion data processing methods, injury and sport types, and application areas, were extracted and analyzed.

RESULTS

Forty-two studies met the inclusion criteria. Inertial measurement unit (IMU) sensors were the most commonly used for motion data collection. Sensor fusion techniques have gained traction, particularly for rehabilitation assessment. Knee injuries and joint sprains were the most frequently studied injuries, with statistical methods being the predominant approach to data analysis.

CONCLUSIONS

This review comprehensively explains sensor-based techniques in sports injury motion analysis. Significant research gaps, including the integration of advanced processing techniques, real-world applicability, and the inclusion of underrepresented domains such as adaptive sports, highlight opportunities for innovation. Bridging these gaps can drive the development of more effective, accessible, and personalized solutions in sports health.

Validity, reliability, and bias between instrumented pedals and loadsol insoles during stationary cycling

The purpose of this study was to evaluate the validity and reliability of the loadsol in measuring pedal reaction force (PRF) during stationary cycling as well as lower limb symmetry. Ten healthy participants performed bouts of cycling at 1kg, 2kg, and 3kg workloads (conditions) on a cycle ergometer. The ergometer was fitted with instrumented pedals and participants wore loadsol plantar pressure insoles. A 3 x 2 (Condition x Sensor Type) ANOVA was used to examine the differences in measured peak PRF, impulse, and symmetry indices. Root mean square error, intraclass correlation coefficients, and Passing-Bablok regressions were used to further assess reliability and validity. The loadsol demonstrated poor (< 0.5) to excellent (> 0.9) agreement as measured by intraclass correlation coefficients for impulse and peak PRF. Passing-Bablok regression revealed a systematic bias only when assessing all workloads together for impulse with no bias present when looking at individual workloads. The loadsol provides a consistent ability to measure PRF and symmetry when compared to a gold standard of instrumented pedals but exhibits an absolute underestimation of peak PRF. This study provides support that the loadsol can identify and track symmetry differences in stationary cycling which means there is possible usage for clinical scenarios and interventions in populations with bilateral asymmetries such as individuals with knee replacements, limb length discrepancies, diabetes, or neurological conditions. Further investigation of bias should be conducted in longer cycling sessions to ensure that the loadsol system is able to maintain accuracy during extended use.

Are lower limb symmetry and self-reported symptoms associated with functional and neuromuscular outcomes in Brazilian adults with anterior cruciate ligament reconstruction? A cross-sectional study

INTRODUCTION

After anterior cruciate ligament (ACL) reconstruction, determining readiness to return to participation is challenging. The understanding of which neuromuscular performance parameters are associated with limb symmetry and self-reported symptoms may be useful to improve monitoring the rehabilitation towards adequate decision-making to return.

OBJECTIVES

To compare the ACL-operated and injury-free lower limbs regarding functional performance; and to investigate whether lower limb strength and functional performance are associated with self-reported symptoms and functional lower limb symmetry.

METHOD

Thirty-four participants were included. Functional performance was assessed by using the Y-Balance test, Single-leg Hop, and Functional Movement Screen. An isokinetic dynamometer was used to evaluate the strength levels in open and closed kinetic chains. The functional lower limb symmetry was calculated considering the single-leg hop test results for each lower limb.

RESULTS

There were no differences in dynamic balance (Y-Balance) between the operated and injury-free limbs. The operated limb presented a worst performance in the single-leg hop. Self-reported symptoms prevalence and lower limb symmetry were associated with knee extension strength and functional performance (Y-Balance).

CONCLUSION

Individuals submitted to ACL-reconstruction presented worse functional performance in the operated limb compared to the injury-free limb. Both knee strength and dynamic balance were associated with limb symmetry and self-reported symptoms.

Women's College Volleyball Players Exhibit Asymmetries During Double-Leg Jump Landing Tasks

CONTEXT

Women's volleyball requires frequent and repetitive jumping that when performed with altered biomechanics, including kinematic or kinetic asymmetry, may place the athlete at high risk for injury. This study identified and analyzed lower-extremity biomechanical asymmetries in college women's volleyball players during standard and sport-specific double-leg landing tasks.

DESIGN

Cross-sectional laboratory study.

METHODS

Eighteen female college volleyball players were analyzed using standard 3D motion capture techniques during a drop vertical jump and an unanticipated lateral reactive jump task. Repeated-measures multivariate analysis of variance identified asymmetries in kinematic and kinetic variables of each task.

RESULTS

Average symmetry indices ranged from 9.3% to 31.3% during the drop vertical jump and 11.9% to 25.6% during the reactive jump task. During the drop vertical jump, the dominant limb exhibited lower knee abduction moments (P = .03), ankle dorsiflexion moments (P = .02), ankle eversion moments (P = .003) and vertical ground reaction forces (P = .03), and greater ankle inversion moments (P = .001). Both kinematic (λ = 0.27, P = .03) and kinetic (λ = 0.12, P = .008) asymmetries were identified during the reactive jump task. The dominant limb exhibited greater peak knee flexion (P = .003) and ankle dorsiflexion (P = .02) angles, and greater ankle dorsiflexion (P = .005) and inversion (P = .03) moments than the nondominant limb.

CONCLUSIONS

These asymmetries observed during double-leg landing tasks may predispose volleyball athletes to unilaterally higher ground reaction or muscle forces and ultimately a greater risk of injury during landing.

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

OBJECTIVES

Determine the safety and initial efficacy of a novel biofeedback intervention to improve landing mechanics in patients following anterior cruciate ligament reconstruction (ACLR).

METHODS

Forty 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.

RESULTS

No 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.

CONCLUSION

This 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).

The use of wearable technology as an assessment tool to identify between-limb differences during functional tasks following ACL reconstruction. A scoping review

OBJECTIVE

To report how wearable sensors have been used to identify between-limb deficits during functional tasks following ACL reconstruction and critically examine the methods used.

METHODS

We performed a scoping review of studies including participants with ACL reconstruction as the primary surgical procedure, who were assessed using wearable sensors during functional movement tasks (e.g., balance, walking or running, jumping and landing) at all postsurgical time frames.

RESULTS

Eleven studies met the inclusion criteria. The majority examined jumping-landing tasks and reported kinematic and kinetic differences between limbs (involved vs. unninvolved) and groups (injured vs. controls). Excellent reliability and moderate-strong agreement with laboratory protocols was indicated, with IMU sensors providing an accurate estimation of kinetics, but the number of studies and range of tasks used were limited. Methodological differences were present including, sensor placement, sampling rate, time post-surgery and type of assessment which appear to affect the outcome.

CONCLUSIONS

Wearable sensors consistently identified between-limb and group deficits following ACL reconstruction. Preliminary evidence suggests these technologies could be used to monitor knee function during rehabilitation, but further research is needed including, validation against criterion measures. Practitioners should also consider how the methods used can affect the accuracy of the outcome.

Kinetic measurement system use in individuals following anterior cruciate ligament reconstruction: a scoping review of methodological approaches

PURPOSE

Our primary objectives were to (1) describe current approaches for kinetic measurements in individuals following anterior cruciate ligament reconstruction (ACLR) and (2) suggest considerations for methodological reporting. Secondarily, we explored the relationship between kinetic measurement system findings and patient-reported outcome measures (PROMs).

METHODS

We followed the PRISMA extension for scoping reviews and Arksey and O'Malley's 6-stage framework. Seven electronic databases were systematically searched from inception to June 2020. Original research papers reporting parameters measured by kinetic measurement systems in individuals at least 6-months post primary ACLR were included.

RESULTS

In 158 included studies, 7 kinetic measurement systems (force plates, balance platforms, pressure mats, force-measuring treadmills, Wii balance boards, contact mats connected to jump systems, and single-sensor insoles) were identified 4 main movement categories (landing/jumping, standing balance, gait, and other functional tasks). Substantial heterogeneity was noted in the methods used and outcomes assessed; this review highlighted common methodological reporting gaps for essential items related to movement tasks, kinetic system features, justification and operationalization of selected outcome parameters, participant preparation, and testing protocol details. Accordingly, we suggest considerations for methodological reporting in future research. Only 6 studies included PROMs with inconsistency in the reported parameters and/or PROMs.

CONCLUSION

Clear and accurate reporting is vital to facilitate cross-study comparisons and improve the clinical application of kinetic measurement systems after ACLR. Based on the current evidence, we suggest methodological considerations to guide reporting in future research. Future studies are needed to examine potential correlations between kinetic parameters and PROMs.

The impact of standardized footwear on load and load symmetry

BACKGROUND

The inability to standardize footwear is a potential issue when measuring landing kinetics in non-laboratory settings. This study determined the impact of not standardizing footwear on load and load symmetry during landing. A secondary purpose of this study was to introduce the Load Analysis Program, an open-source MATLAB® user-interface for computing kinetic and kinetic symmetry from data collected using loadsol® sensors.

METHODS

Forty uninjured participants completed bilateral and unilateral landing tasks in their own preferred athletic footwear and in laboratory-standardized footwear. Peak impact force, impulse, and a limb symmetry index of both kinetic outcomes were computed using loadsol® sensors (200 Hz) for both footwear conditions, and compared between footwear conditions using intraclass correlation coefficients and Bland-Altman plots.

FINDINGS

The agreement between the preferred and standardized conditions was good to excellent for peak impact force, peak impact force limb symmetry index, and impulse limb symmetry index during the bilateral task (intraclass correlation coefficient = 0.870-0.951). The agreement was moderate to poor for unilateral limb symmetry index measures (intraclass correlation coefficient = 0.399-0.516). During the preferred footwear condition, impulse was greater for the left limb during bilateral landing, and peak impact force during unilateral landing on the right limb was decreased, when compared to the standardized footwear condition (p < 0.05).

INTERPRETATION

These results suggest that while not standardizing footwear can alter the results of certain load metrics, laboratory-relevant landing mechanics information can be obtained with participants wearing their own footwear.

Bilateral Squatting Mechanics Are Associated With Landing Mechanics in Anterior Cruciate Ligament Reconstruction Patients

BACKGROUND

Proper lower extremity biomechanics during bilateral landing is important for reducing injury risk in athletes returning to sports after anterior cruciate ligament reconstruction (ACLR). Although landing is a quick ballistic movement that is difficult to modify, squatting is a slower cyclic movement that is ideal for motor learning.

HYPOTHESIS

There is a relationship between lower extremity biomechanics during bilateral landing and bilateral squatting in patients with an ACLR.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 41 patients after a unilateral ACLR (24 men, 17 women; 5.9 ± 1.4 months after ACLR) completed 15 unweighted bilateral squats and 10 bilateral stop-jumps. Three-dimensional lower extremity kinematics and kinetics were collected, and peak knee abduction angle, knee abduction/adduction range of motion, peak vertical ground-reaction force limb symmetry index (LSI), vertical ground-reaction force impulse LSI, and peak knee extension moment LSI were computed during the descending phase of the squatting and landing tasks. Wilcoxon signed-rank tests were used to compare each outcome between limbs, and Spearman correlations were used to compare outcomes between the squatting and landing tasks.

RESULTS

The peak vertical ground reaction force, the vertical ground reaction force impulse, and the peak knee extension moment were reduced in the surgical (Sx) limb relative to the nonsurgical (NSx) limb during both the squatting and landing tasks (P < .001). The relationship between squatting and landing tasks was strong for the peak knee abduction angle (R = 0.697-0.737; P < .001); moderate for the frontal plane knee range of motion (NSx: R = 0.366, P = .019; Sx: R = 0.418, P = 0.007), the peak knee extension moment LSI (R = 0.573; P < .001), the vertical ground reaction force impulse LSI (R = 0.382; P < .014); and weak for the peak vertical ground reaction force LSI (R = 0.323; P = .039).

CONCLUSION

Patients who have undergone an ACLR continue to offload their surgical limb during both squatting and landing. Additionally, there is a relationship between movement deficits during squatting and movement deficits during landing in patients with an ACLR preparing to return to sports.

CLINICAL RELEVANCE

As movement deficits during squatting and landing were related before return to sports, this study suggests that interventional approaches to improve squatting biomechanics may translate to improved landing biomechanics in patients with an ACLR.

Including jump height when normalizing single hop impact kinetics can change the directionality of findings

BACKGROUND

Assessing landing kinetics during hop testing could improve return to sport decisions following anterior cruciate ligament reconstruction (ACL) reconstruction. However, different methods for normalizing kinetic outcomes could influence the interpretation of landing kinetics and therefore the clinical recommendations.

METHODS

Twenty-one females who had returned to sport following primary unilateral ACL reconstructed completed two single hops for maximum distance on each limb. Hop distance, hop height, peak impact force, and impulse were computed for each hop, and peak impact force and impulse magnitudes were assessed when 1) non-normalized 2) normalized by bodyweight, and 3) normalized by peak potential energy during the hop.

FINDINGS

Along with hop distance and height, peak impact force and impulse were found to be lower on the surgical limb relative to the non-surgical limb for both non-normalized data and when normalized to bodyweight only (p < 0.001, d > 0.95). However, peak impact force and impulse were found to be higher on the surgical limb relative to the non-surgical limb when normalizing outcomes to peak potential energy (p < 0.001, d > 1.03).

INTERPRETATION

Different normalization methods result in different interpretations of single hop kinetics. ACL reconstruction patients have shorter hop distances, lower hop heights, lower force magnitudes, and worse energy absorption when hopping on their surgical limb, relative to their non-surgical limb. We believe that normalizing landing kinetics using bodyweight and using peak potential energy provide different information, and as such, we suggest that future research use both methods based on the research question.

Reduction of Risk Factors for ACL Re-injuries using an Innovative Biofeedback Approach: Rationale and Design

Nearly 1 in 60 adolescent athletes will suffer anterior cruciate ligament (ACL) injuries with 90% of these athletes electing to undergo an ACL reconstruction (ACLR) at an estimated annual cost of $3 billion. While ACLR and subsequent rehabilitation allow these athletes to return to sports, they have a 15-fold increased risk of second ACL injuries. The modification of post-operative rehabilitation to improve movement and loading symmetry using visual and tactile biofeedback could decrease the risk factors for sustaining a second ACL injury. Participants included 40 adolescent ACLR patients who were intending to return to full sport participation. This preliminary randomized controlled trial (RCT) examined the changes in knee extension moment symmetry, a known risk factor for second ACL injuries, during landing from a stop-jump task between the following time-points: pre-intervention, immediate post-intervention, and subsequent follow-up 6-weeks post-intervention. Participants met twice per week for six-weeks (12-session). The intervention included bilateral squat biofeedback (visual and tactile); the attention control group attended weekly educational sessions. This RCT enrolled and randomize 40 participants over a two-and-a-half-year period. All participants were greater than 4.5 months post-op from a primary, unilateral ACLR and were released to participate by their treating physician. The findings from this pilot biofeedback RCT will provide critical effect size estimates for use in subsequent larger clinical trials.

Incorporating Internal and External Training Load Measurements in Clinical Decision Making After ACL Reconstruction: A Clinical Commentary

BACKGROUND AND PURPOSE

Poor outcomes after anterior cruciate ligament reconstruction (ACLr), including the relatively high risk of suffering a subsequent ACL injury, suggest the need to optimize rehabilitation and return-to-sport testing. The purpose of this commentary is to introduce clinicians to the concept of monitoring training load during rehabilitation, to review methods of quantifying internal and external loads, and to suggest ways that these technologies can be incorporated into rehabilitation progressions and return-to-sport decisions after anterior ACLr.

DESCRIPTION OF TOPIC WITH RELATED EVIDENCE

Quantifying and identifying the effects of training load variables, external (distance, impacts, decelerations) and internal (heart rate, heart rate variability) workload, during rehabilitation can indicate both positive (improved physical, physiological, or psychological capacity) or negative (heightened risk for injury or illness) adaptations and allow for the ideal progression of exercise prescription. When used during return-to-sport testing, wearable technology can provide robust measures of movement quality, readiness, and asymmetry not identified during performance-based testing.

DISCUSSION / RELATION TO CLINICAL PRACTICE

Researchers have reported the actual in-game demands of men and women of various ages and competition levels during multi-directional sport. Wearable technology can provide similar variables during rehabilitation, home exercise programs, and during on-field transition back to sport to ensure patients have met the expected fitness capacity of their sport. Additionally, clinicians can use internal load measures to objectively monitor patient's physiological responses to rehabilitation progressions and recovery rather than relying on subjective patient-reported data.

LEVEL OF EVIDENCE

5.

Is It Time We Better Understood the Tests We are Using for Return to Sport Decision Making Following ACL Reconstruction? A Critical Review of the Hop Tests

There has been a move towards a criterion-based return to play in recent years, with 4 single-leg hop tests commonly used to assess functional performance. Despite their widespread integration, research indicates that relationships between ‘passing’ ‘hop test criteria and successful outcomes following rehabilitation are equivocal, and, therefore, require further investigation. This critical review includes key information to examine the evolution of these tests, their reliability, relationships with other constructs, and sensitivity to change over time. Recommendations for how measurement and administration of the tests can be improved are also discussed. The evidence presented in this review shows that hop tests display good reliability and are sensitive to change over time. However, the use of more than 2 hop tests does not appear to be necessary due to high collinearity and no greater sensitivity to detect abnormality. The inclusion of other hop tests in different planes may give greater information about the current function of the knee, particularly when measured over time using both relative and absolute measures of performance. It is recommended that the contralateral limb be tested prior to surgery for a more relevant benchmark for performance, and clinicians are strongly advised to measure movement quality, as hop distance alone appears to overestimate the recovery of the knee.

Effect of speed and gradient on plantar force when running on an AlterG® treadmill

BACKGROUND

Anti-gravity treadmills are used to decrease musculoskeletal loading during treadmill running often in return to play rehabilitation programs. The effect different gradients (uphill/downhill running) have on kinetics and spatiotemporal parameters when using an AlterG® treadmill is unclear with previous research focused on level running only.

METHODS

Ten well-trained healthy male running athletes ran on the AlterG® treadmill at varying combinations of bodyweight support (60, 80, and 100% BW), speed (12 km/hr., 15 km/hr., 18 km/hr., 21 km/hr., and 24 km/hr), and gradients (- 15% decline, - 10, - 5, 0, + 5, + 10 + 15% incline), representing a total of 78 conditions performed in random order. Maximum plantar force and contact time were recorded using a wireless in-shoe force sensor insole system.

RESULTS

Regression analysis showed a linear relationship for maximum plantar force with bodyweight support and running speeds for level running (p < 0.0001, adj. R² = 0.604). The linear relationship, however, does not hold for negative gradients at speeds 12 & 15 km/h, with a relative 'dip' in maximum plantar force across all assisted bodyweight settings.

CONCLUSIONS

Maximum plantar force peaks are larger with faster running and smaller with more AlterG® assisted bodyweight support (athlete unweighing). Gradient made little difference except for a downhill grade of - 5% decreasing force peaks as compared to level or uphill running.

Individual hop analysis and reactive strength ratios provide better discrimination of ACL reconstructed limb deficits than triple hop for distance scores in athletes returning to sport

BACKGROUND

The triple hop for distance test commonly uses a limb symmetry index (LSI) 'pass' threshold of >90% for total hop distance following anterior cruciate ligament reconstruction (ACLR). However, understanding the manner in which athletes generate and dissipate forces during consecutive hops within the test may provide greater insight into residual limb deficits. The aim of the study was to examine reactive strength ratios (RSR) of individual hops during a triple hop test in a cohort of ACLR patients at discharge prior to return-to-sport.

METHODS

Twenty male athletes (24.6 ± 4.2 years; height 175.3 ± 10.2 cm; mass 73.6 ± 14.5 kg) completed the test on both non-operated and operated limbs. Total distance hopped, contact times, flight times and RSR were collected for each hop using a floor-level optical measurement system.

RESULTS

Significant, small to moderate between-limb differences (p < 0.05; d = 0.45-0.72) were shown for triple hop distance, flight time and RSR for each hop, with lower performance consistently displayed in the operated limb. Large, significant differences in RSR were evident between hops one and two on the operated limb (p < 0.05; d = 0.97). Despite 80% of participants achieving >90% LSI for total hop distance, less than 50% of participants reached the >90% LSI threshold for RSR.

CONCLUSIONS

Standardised LSI 'pass' thresholds (>90% LSI) for triple hop distance may mask residual deficits in reactive strength performance of operated limbs; therefore, more detailed analyses of individual hop performance may be warranted to enhance return to sport criteria following ACLR.

Hop testing symmetry improves with time and while wearing a functional knee brace in anterior cruciate ligament reconstructed athletes

BACKGROUND

There is currently no consensus among orthopaedic surgeons as to when patients with anterior cruciate ligament reconstruction are ready to return to sport or whether or not patients should wear a functional knee brace during athletic activity. The purpose of the present study was to determine the effects of time since return to sport and of a functional knee brace on hop distance and loading symmetry during hop testing in patients with anterior cruciate ligament reconstruction.

METHODS

Twenty-eight patients with anterior cruciate ligament reconstruction completed hop testing after being released to return to sport and again 3 months later, both with and without wearing a custom fit extension constraint functional knee brace. The loadsol® captured plantar loading data (100 Hz) to quantify peak impact force, loading rate, and impulse during the final landing of every hop test. A limb symmetry index was calculated between surgical and non-surgical limbs for hop distance and loading measures.

FINDINGS

Wearing a knee brace increased hop distance symmetry during the single and crossover hop tests and peak impact force symmetry on each test (all p < 0.05). While single (p = 0.022) and triple (p = 0.002) hop distance symmetry increased with time, there was no effect of time on any loading symmetry outcomes.

INTERPRETATION

These results support using a functional knee brace during athletic activities for improving symmetry in the early return to sport period. These results also support previous findings that while hop distance symmetry improves with time, asymmetrical landing mechanics do not and should be addressed clinically.