Knee flexor strength at 6 months after anterior cruciate ligament reconstruction using hamstring tendon can be predicted from that at 3 months.

PURPOSE: This study aimed to identify factors influencing persistent muscle weakness in knee flexor strength after anterior cruciate ligament (ACL) reconstruction using the hamstring tendon and establish a clear cut-off value at 3 months postoperatively for the limb symmetry index (LSI) to exceed 90% at 6 months postoperatively. METHODS: One hundred forty-eight patients undergoing ACL reconstruction were included and categorised into two groups based on knee flexor strength at 6 months postoperatively: patients with LSI of 90% or greater (achieved group: n = 114) and patients with LSI less than 85% (nonachieved group: n = 34). Items with significant differences between the two groups (preoperative waiting period, LSI to body weight ratio of knee flexor and extensor strength at 3 months postoperatively and peak torque angle of knee flexor muscle) were included in the multiple logistic regression analysis. Additionally, a receiver operating characteristic curve was used to calculate the cut-off value of the LSI at 3 months postoperatively, which was required to achieve the LSI criteria for knee flexor strength 6 months postoperatively. RESULTS: Multiple logistic regression analysis extracted the preoperative waiting period and LSI for knee flexor strength at 3 months postoperatively. The cut-off value at 3 months postoperatively was 76.9% (area under the curve value, 0.82; sensitivity, 0.76; and specificity, 0.81) of the LSI. CONCLUSION: The LSI of at least 76.9% for knee flexor strength at 3 months after ACL reconstruction was an indicator for achieving the 6 months postoperatively. This is a criterion to aim for, considering the stress on the graft and the regeneration process of the semitendinosus tendon. LEVEL OF EVIDENCE: Level III.

Residual deficits of knee and hip joint coordination and clinical performance after return to sports in athletes with anterior cruciate ligament reconstruction.

BACKGROUND: Biomechanical changes and neuromuscular adaptations have been suggested as risk factors of secondary injury in individuals after anterior cruciate ligament reconstruction (ACLr). To achieve a better understanding of preventive mechanisms, movement quality is an important factor of consideration. Few studies have explored time-series analysis during landing alongside clinical performance in injured and non-injured individuals. The purpose of the study was to investigate the biomechanical risks of recurrent injury by comparing clinical and jump-landing performance assessments between athletes with ACLr and healthy controls. METHOD: This study was observational study. Sixteen athletes with and without ACLr voluntarily participated in clinical and laboratory measurements. Single-leg hop distance, isokinetic tests, landing error score, and limb symmetry index (LSI) were included in clinical report. Lower limb movements were recorded to measure joint biomechanics during multi-directional landings in motion analysis laboratory. Hip-knee angle and angular velocity were explored using discrete time-point analysis, and a two-way mixed analysis of variance (2 × 4, group × jump-landing direction) was used for statistical analysis. Time series and hip-knee coordination analyses were performed using statistical parametric mapping and descriptive techniques. RESULTS: Significantly lower single-leg hop distance was noted in ACLr group (158.10 cm) compared to control group (178.38 cm). Although the hip and knee moments showed significant differences between four directions (p < 0.01), no group effect was observed (p > 0.05). Statistical parametric mapping showed significant differences (p ≤ 0.05) between groups for hip abduction and coordinate plot of hip and knee joints. Athletes with ACLr demonstrated a higher velocity of hip adduction. Time-series analysis revealed differences in coordination between groups for frontal hip and knee motion. CONCLUSIONS: Athletes with ACLr landed with poor hip adduction control and stiffer knee on the involved side. Multi-directions landing should be considered over the entire time series, which may facilitate improved movement quality and return to sports in athletes with ACLr.

Estimating the Reliability and Validity of the Quadrant Hop Test in the Assessment of the Functional Stability of the Knee.

Background Many sporting activities demand multidirectional skills and movements, emphasizing the importance of various fitness components such as functional stability, strength, power, endurance, and range of motion. These aspects must be thoroughly assessed before athletes can return to sports safely following an injury. Although the single-leg hop test (SHT) is widely used as the gold standard for evaluating joint stability, it has limitations in assessing multidirectional movements. Therefore, further research is necessary to explore whether increasing the dynamicity of the hop test in different directions enhances its sensitivity in assessing knee joint stability across all four directions. The objective of this study was to investigate the applicability of a new functional assessment tool, the quadrant hop test (QHT), for evaluating lower limb functional stability. Methodology One hundred nineteen amateur sportsmen who are in the age group of 18-25 years with a limb symmetry index of the lower limb calculated through SHT of >80% were included. All the participants performed the SHT, a triple hop test (THT), a crossover hop test (CHT), and the QHT on two different days, with two investigators assessing the QHT on different days and then recording the measurements of Hop distance. Results The mean difference between SHT, THT, and CHT with QHT was 4.59%, with a moderate correlation between all the hop tests. The Cronbach's alpha revealed good intra-rater (0.917) and inter-rater reliability (0.912) of the QHT. Conclusion The QHT proves to be a reliable and valid measure for assessing the functional stability of the lower limb and is 4.59% more sensitive than SHT, THT, and CHT in assessing knee stability and in return to sports criteria.

Strength of the Uninvolved Limb Following Return to Activity After ACL Injury: Implications for Symmetry as a Marker of Sufficient Strength.

Background: Muscular strength deficits are common after ACL injury. While the Limb Symmetry Index (LSI), using the uninvolved limb as a reference, is widely used, negative strength adaptations may affect both limbs post-injury. It is uncertain how the strength of the uninvolved limb in those with an ACL injury compares to uninjured individuals, making it unclear whether it is appropriate as a benchmark for determining sufficient strength. Purpose: To compare the strength of key lower extremity muscles of the uninvolved limb in those with history of ACL injury (ACL-I) to the dominant limb in individuals with no history of ACL injury (control). Study Design: Cross-sectional study. Methods: A total of 5,727 military cadets were examined, with 82 females and 126 males in the ACL-I group and 2,146 females and 3,373 males in the control group. Maximum isometric strength was assessed for six muscle groups measured with a hand-held dynamometer. Separate two-way ANOVAs with limb and sex were performed for each muscle group. Results: Significant main effects for limb were observed with the uninvolved limb in the ACL-I group displaying greater strength compared to the dominant limb in the control group for the quadriceps, hamstrings, and gluteus medius, but effect sizes were small (Cohen's d <0.25). Significant main effects for sex were observed with greater male muscular strength in all six muscle groups with small to large effect sizes (Cohen's d 0.49-1.46). No limb-by-sex interactions were observed. Conclusions: There was no evidence of reduced strength in the uninvolved limb in those with a history of ACL injury compared to the dominant limb in those with no prior ACL injury. This finding suggests that, after clearance to return to activities, the uninvolved limb can be used as a standard for comparison of sufficient strength, including when using the LSI. Level of Evidence: Level 3.

Validity of a commercially available load cell dynamometer in measuring isometric knee extension torque in patients with knee disorders.

OBJECTIVE: Assess the validity of hand-held dynamometry (HHD) and the Tindeq Progressor (TP) in assessing peak isometric knee extension torque and limb symmetry index (LSI) versus isokinetic dynamometer (IKD). DESIGN: Prospective cross-sectional study. SETTING: Laboratory. PARTICIPANTS: 31 individuals with unilateral knee disorders (21 female; 28.3 ± 11 years). MAIN OUTCOME MEASURES: Peak isometric knee extension torque; Knee extension LSI. RESULTS: Strong to almost perfect (p < 0.001) correlations (Cohen's Kappa k) with IKD were found for both devices for peak torque of the uninvolved limb (HHD [k = 0.84], TP [k = 0.91]) and involved limb (HHD [k = 0.93], TP [k = 0.98]). For LSI, moderate to strong (p < 0.001) correlations with IKD were found for HHD (k = 0.79) and TP (k = 0.89). Mean bias errors were equivalent for determining LSI (HHD = 0.02%; TP = 0.03%). Both HHD and TP were highly sensitive (96.2-100.0%) and specific (100.0%) at the 70% LSI threshold. TP showed higher sensitivity and specificity at the 90% LSI threshold. CONCLUSION: HHD and TP are valid in measuring isometric knee extension torque with the reference standard IKD. TP showed superior validity in identifying LSI. TP also shows greater specificity in identifying the 90% LSI threshold.

Establishing Normal Variances and Expectations for Quadriceps Limb Symmetry Index Benchmarks Based on Time from Surgery After Anterior Cruciate Ligament Reconstruction.

The anticipated timeline for muscle strength as well as return to running and sports are some of the most common inquiries by patients undergoing anterior cruciate ligament reconstruction. Despite the popularity of this procedure, the answers to these inquiries are not well described in the literature. The purpose of this study was to evaluate the range of quadriceps strength percentage and function benchmarks at various points after anterior cruciate ligament reconstruction surgery based on sex, age, and graft. Design: Observational Cohort Study. Methods: Patients who underwent anterior cruciate ligament reconstruction (ACLR) were evaluated at various points after their surgery with handheld dynamometer assessments. Additional hop and balance testing was performed and patients were evaluated for clearance for running and sport via a physical therapist directed functional movement assessment (FMA). The progression of quadriceps symmetry throughout the postoperative period was examined with multi-level models, estimates of time to reach 70%, 80%, and 90% quadriceps symmetry were obtained from the fitted model. Results: A total of 164 patients were evaluated. Patients either received bone-tendon-bone (BTB) autograft (n=118) or BTB allograft (n=46) for their ACL graft. Average age was 31.1 years-of-age (SD: 13.6). Males undergoing ACLR using BTB autograft (n=53) were able to achieve 80% quadriceps symmetry earlier than females (n=65) (5.7 months vs 7.1 months), were cleared to return to run sooner (5.6 months vs 6.8 months) and passed an FMA exam earlier (8.5 months vs 10 months). Males undergoing ACLR with allograft (n=13) were able to achieve 80% quadriceps symmetry earlier than females (n=33) (3.9 months vs 5.4 months) and were cleared to run sooner (4.5 months vs 5.8 months). Conclusion: Patients undergoing BTB autograft obtain 80% quadriceps symmetry at an average of 5.7 months for males and 7.1 months for females. Individuals under the age of 25 obtain their quadriceps symmetry faster and are cleared to return to running faster than individuals over 25. Male sex is associated with decreased amount of time to obtain clearance for running and for full activity. Male sex is associated with decreased amount of time to regain quadriceps symmetry however this was not significant. Level of Evidence: 4 (Case series).

Abnormal Lower Limb Biomechanics During a Bilateral Vertical Jump Despite the Symmetry in Single-Leg Vertical Hop Height in Athletes After ACL Reconstruction.

Background: A limb symmetry index (LSI) of >90% for single-leg horizontal hop distance is recommended as a cutoff point for safe return to sports after anterior cruciate ligament reconstruction (ACLR). Despite achieving this threshold, abnormal lower limb biomechanics continue to persist in athletes after ACLR. Symmetry in single-leg vertical hop height appears to be more difficult to achieve and can be a better representation of knee function than single-leg horizontal hop distance. Purpose: To explore whether an LSI of >90% for single-leg vertical hop height can represent normal lower limb biomechanics in athletes during a bilateral vertical jump after ACLR. Study Design: Controlled laboratory study. Methods: According to the LSI for single-leg vertical hop height, 46 athletes who had undergone ACLR with an autologous ipsilateral bone-patellar tendon-bone or hamstring tendon graft were divided into a low symmetry group (LSI <90%; n = 23) and a high symmetry group (LSI >90%; n = 23), and 24 noninjured athletes were selected as the control group. The kinematic and kinetic characteristics during a bilateral vertical jump were compared between the low symmetry, high symmetry, and control groups. Results: During the propulsion phase of the bilateral vertical jump, the operated side in the high symmetry group showed a lower knee extension moment than the nonoperated side (P = .001). At peak vertical ground-reaction force, the operated side in the high symmetry group showed a lower knee internal rotation moment compared with the control group (P = .016). Compared with the nonoperated side, the operated side in the high symmetry group showed a higher hip extension moment (P = .002), lower knee extension moment (P < .001), lower ankle plantarflexion moment (P < .001), and lower vertical ground-reaction force (P = .023). Conclusion: Despite achieving an LSI of >90% for single-leg vertical hop height, athletes after ACLR showed abnormal lower limb biomechanical characteristics during the bilateral vertical jump. Clinical Relevance: Symmetrical single-leg vertical hop height may not signify ideal biomechanical or return-to-sports readiness in this population.

Reduction in re-rupture rates following implementation of return-to-sport testing after anterior cruciate ligament reconstruction in 313 patients with a mean follow-up of 50 months.

OBJECTIVES: The objective of this study was to assess the mid-term effectiveness of a return to sport (RTS) test in relation to preventing anterior cruciate ligament (ACL) re-rupture and contralateral ACL injury following ACL reconstruction (ACLR). Furthermore, this study aimed to assess the timing of passing a, RTS-test after surgery, and the effect age has on RTS outcomes. METHODS: Patients undergoing ACLR between August 2014 and December 2018 took an RTS-test following rehabilitation. The RTS-test consisted of the Anterior Cruciate Ligament Return to Sport After Injury Scale, a single-leg hop, a single-leg triple hop, a single-leg triple cross-over hop, a box-drop vertical jump down, a single-leg 4-rep max-incline leg press, and a modified agility T test. RTS-passing criteria were ≥90% limb symmetry index in addition to defined takeoff and landing parameters. Mid-term review assessed sporting level, ACL re-injury, and contralateral ACL injury. RESULTS: A total of 352 patients underwent RTS-testing, following ACLR with 313 (89%) contactable at follow-up, a mean of 50 months (standard deviation: 11.41, range: 28-76) after surgery. The re-rupture rate was 6.6% after passing the RTS-test and 10.3% following failure (p â€‹= â€‹0.24), representing a 36% reduction. Contralateral ACL injury rate after surgery was 6% and was 19% lower in those passing the RTS test. The mean age of patients passing their first RTS-test was significantly higher than that of those who failed (p â€‹= â€‹0.0027). Re-ruptures in those who passed the RTS test first time occurred late (>34 months), compared to those who failed first time, which all occurred early (<33 months) (p â€‹= â€‹0.0015). The mean age of re-rupture was significantly less than those who did not sustain a re-rupture (p â€‹= â€‹0.025). CONCLUSION: Passing a RTS-test following ACLR reduces ACL re-rupture by 36.21% and contralateral ACL injury by 19.15% at mid-term follow-up. Younger patients are more likely to fail a RTS-test and are at higher risk of contralateral ACL rupture.

Restoring Knee Flexor Strength Symmetry Requires 2 Years After ACL Reconstruction, But Does It Matter for Second ACL Injuries? A Systematic Review and Meta-analysis.

BACKGROUND: It is unknown whether knee flexor strength recovers after anterior cruciate ligament (ACL) reconstruction with a hamstring tendon (HT) autograft and whether persistent knee flexor strength asymmetry is associated to a second ACL injury. OBJECTIVE: We aimed to systematically review (1) whether knee flexor strength recovers after ACL reconstruction with HT autografts, and (2) whether it influences the association with a second ACL injury. A third aim was to summarize the methodology used to assess knee flexor strength. DESIGN: Systematic review and meta-analysis reported according to PRISMA. METHODS: A systematic search was performed using the Cochrane Library, Embase, Medline, PEDRo, and AMED databases from inception to December 2021 and until completion in January 2023. Human clinical trials written in English and conducted as randomized controlled trials, longitudinal cohort, cross-sectional, and case-control studies on patients with index ACL reconstructions with HT autografts harvested from the ipsilateral side were considered. Knee flexor strength was measured isokinetically in both the reconstructed and uninjured limb to enable the calculation of the limb symmetry index (LSI). The Risk of Bias Assessment Tool for Non-Randomized Studies was used to assess risk of bias for non-randomized studies and the revised Cochrane Risk of Bias tool was used for randomized controlled trials. For the meta-analysis, the LSI (mean ± standard error) for concentric knee flexor strength at angular velocities of 60°/second (s) and 180°/s preoperatively and at 3 months, 6 months, 12 months, and 24 months were pooled as weighted means with standard errors. RESULTS: The search yielded 64 studies with a total of 8378 patients, which were included for the assessment of recovery of knee flexor strength LSI, and a total of 610 patients from four studies that investigated the association between knee flexor strength and second ACL injuries. At 1 year after ACL reconstruction, the knee flexor strength LSI had recovered to 89.0% (95% CI 87.3; 90.7%) and 88.3% (95% CI 85.5; 91.1%) for the velocities of 60°/s and 180°/s, respectively. At 2 years, the LSI was 91.7% (95% CI 90.8; 92.6%) and 91.2% (95% CI 88.1; 94.2%), for velocities of 60°/s and 180°/s, respectively. For the association between knee flexor strength and second ACL injuries, there was insufficient and contradictory data. CONCLUSIONS: There was low to very low certainty of evidence indicating that the recovery of knee flexor strength LSI, defined as ≥ 90% of the uninjured side, takes up to 2 years after ACL reconstruction with HT autografts. Whether knee flexor strength deficits influence the association of second ACL injuries is still uncertain. There was considerable heterogeneity in the methodology used for knee flexor strength assessment, which together with the low to very low certainty of evidence, warrants further caution in the interpretation of our results. REGISTRATION NUMBER: CRD42022286773.

Strength symmetry after autograft anterior cruciate ligament reconstruction.

OBJECTIVE: To compare postoperative isometric quadriceps strength indices (QI%) and hamstring strength limb symmetry indices (HI%) between partial thickness quadriceps tendon (pQT), full thickness quadriceps tendon (fQT), and bone-patellar-tendon bone (BPTB) autograft anterior cruciate ligament reconstruction (ACLR). METHODS: Patients with primary ACLR with pQT, fQT, or BPTB autograft with the documentation of quantitative postoperative strength assessments between 2016 and 2021 were included. Isometric Biodex data, including QI% and HI% (calculated as the percentage of involved to uninvolved limb strength) were collected between 5 and 8 months and between 9 and 15 months postoperatively. RESULTS: In total, 124 and 51 patients had 5-8- and 9-15-month follow-up strength data, respectively. No significant difference was detected between groups for sex. However, patients undergoing fQT were found to be older than those undergoing BPTB (24.6±7 vs 20.2±5; â€‹p = 0.01). There were no significant differences in the number of concomitant meniscus repairs between the groups (pQT vs. fQT vs. BPTB). No significant differences were detected in median (min-max) QI% between pQT, fQT, and BPTB 5-8 months [87 â€‹% (44%-130 â€‹%), 84 â€‹% (44%-110 â€‹%), 82 â€‹% (37%-110 â€‹%) or 9-15 months [89 â€‹% (50%-110 â€‹%), 89 â€‹% (67%-110 â€‹%), and 90 â€‹% (74%-140 â€‹%)] postoperatively. Similarly, no differences were detected in median HI% between the groups 5-8 months or 9-15 months postoperatively. CONCLUSION: The study was unable to detect differences in the recovery of quadriceps strength between patients undergoing ACLR with pQT, fQT, and BPTB autografts at 5-8 months and 9-15-months postoperatively. LEVEL OF EVIDENCE: III.

Limb Symmetry Index of Single-Leg Vertical Jump vs. Single-Leg Hop for Distance After ACL Reconstruction: A Systematic Review and Meta-analysis.

CONTEXT: The limb symmetry index (LSI) is recommended as a milestone of return to play (RTP), and relying on the LSI value of a single-leg hop for distance (SLHD) test may overestimate rehabilitation status. Identifying a more reliable functional test can help to carefully make decisions for RTP. OBJECTIVE: The aim was to compare the LSI value of the SLHD test with that of a single-leg vertical jump (SLVJ) test after anterior cruciate ligament reconstruction (ACLR) and determine which test provides lower LSI values. DATA SOURCES: The PubMed, Web of Science, Embase, and Cochrane Library databases were searched from inception to July 2022. STUDY SELECTION: Observational studies with participants who had both SLHD and SLVJ tests after ACLR and LSI values of an SLHD and SLVJ were included. Disagreements were resolved after discussion between the 2 researchers. STUDY DESIGN: Systematic review and meta-analysis. LEVEL OF EVIDENCE: Level 4. DATA EXTRACTION: Data on the primary outcomes (LSI values of the SLVJ and SLHD tests) were collected. Means and standard deviations (SDs) for each variable of interest were used to calculate standardized mean differences (SMDs). RESULTS: A total of 12 studies met the inclusion criteria for the meta-analysis. A total of 587 patients underwent SLHD and SLVJ tests at different time points after ACLR. Compared with the SLHD test, the SLVJ test provided lower LSI values (SMD -0.42; 95% confidence interval (CI) -0.67 to -0.17). Subgroup analysis found that the SLVJ test provided a lower LSI value than the SLHD test in a specific period (approximately 7-18 months after ACLR, SMD -0.53; 95% CI -0.91 to -0.14) and a similar LSI value at other times. CONCLUSION: The SLVJ test provided lower LSI values in a specific period (7-18 months after ACLR).

Comparison between the effect of immersive virtual reality training versus conventional rehabilitation on limb loading and functional outcomes in patients after anterior cruciate ligament reconstruction: A prospective randomized controlled trial.

Purpose: Anterior cruciate ligament injury (ACL) commonly occurs during sporting events. It causes pain, instability and reduction in range of movement of the knee which results in altered balance, reduced strength as well as loading to the involved knee. The challenge to get the patient back to competitive sports level much depends on the rehabilitation process. Post ACLR rehabilitation is challenging due to the long rehabilitation time as well as boring repetitive exercises. The aim of this study is to compare between the effectiveness of using immersive virtual reality (PlayStation VR) in addition to the conventional rehabilitation as an aid in rehabilitation of patients after ACLR in terms of objective functional assessment and pain and subjective knee function scoring. Methods: This randomised controlled trial was undertaken in a tertiary hospital in Malaysia from July 2019 until July 2020. Thirty patients were randomised into a group undergoing purely conventional rehabilitation (Group 1) and a group undergoing both conventional rehabilitation and immersive virtual reality assisted rehabilitation (Group 2). The immersive virtual reality assisted rehabilitation was started at 3 months post operatively for 3 months duration. Limb loading, balance, range of motion, functional hop tests of the knee, pain and subjective scoring of the knee with the International Knee Documentation Committee (IKDC) Scores were measured preoperatively and at 6 months. Results: There were significant differences in terms of improvement of pain scores (p = 0.012) as well as IKDC Scores (p = 0.024) in Group 2 as compared to Group 1. However, there were no significant differences with regards to limb loading, balance, range of motion and functional hop tests of the knee (p > 0.05). No adverse events were observed during the study period. Conclusion: Immersive virtual reality can be used as an adjunct in rehabilitation of patients after ACL reconstruction in terms of improving their pain as well as their subjective knee evaluation. Large randomised control trial is recommended to further investigate the efficacy.

Can Symmetry of Single-Leg Vertical Jump Height Represent Normal Lower Limb Biomechanics of Athletes After Anterior Cruciate Ligament Reconstruction?

BACKGROUND: After anterior cruciate ligament reconstruction (ACLR), single-leg horizontal hop distance limb symmetry index (LSI) >90% is recommended as a cutoff point for safe return to sport (RTS). However, athletes after ACLR have abnormal lower limb biomechanics despite an adequate single-leg hop distance LSI, implying that athletes are at high risk of reinjury. Symmetry of single-leg vertical jump height appears to be more difficult to achieve and can be a better representation of knee function than single-leg horizontal hop distance. HYPOTHESIS: Athletes after ACLR with single-leg jump height LSI >90% had similar biomechanical characteristics to healthy athletes. STUDY DESIGN: Controlled laboratory study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 46 athletes after ACLR were divided into low jump height (LJH, jump height LSI <90%, n = 23) and high jump height (HJH, jump height LSI >90%, n = 23) groups according to symmetry of single-leg vertical jump height, while 24 healthy athletes acted as a control (CONT) group. One-way analysis of variance was used to compare the kinematic and kinetic characteristics of the LJH, HJH, and CONT groups during single-leg vertical jump. RESULTS: Both the LJH and HJH groups demonstrated greater limb asymmetry (lower LSI) during landing compared with the CONT group in knee extension moment (P < 0.05), peak knee flexion angle (P < 0.05), and knee power (P < 0.05). CONCLUSION: Symmetry in single-leg vertical jump height does not represent normal lower limb biomechanics in athletes after ACLR. CLINICAL RELEVANCE: Symmetrical jump height may not signify ideal biomechanical or RTS readiness, but single-leg vertical jump test can be used as a supplement to horizontal hop test or other functional tests to reduce the likelihood of false-negative results in the absence of detailed biomechanical evaluation.

Reliability of Upper Extremity Functional Performance Tests for Overhead Sports Activities.

Background: There is lack of consensus on which tests, particularly upper extremity functional performance tests (FPT) that should be used for clinical decision making to progress a patient through a rehabilitation program or criteria for return to sport (RTS). Consequently, there is a need for tests with good psychometric properties that can be administered with minimal equipment and time. Purpose: (1) To establish the intersession reliability of several open kinetic chain FPT in healthy young adults with a history of overhead sport participation. (2) To examine the intersession reliability of the limb symmetry indices (LSI) from each test. Study Design: Test-retest reliability, single cohort study. Methods: Forty adults (20 males, 20 females) completed four upper extremity FPT during two data collection sessions three to seven days apart: 1) prone medicine ball drop test 90°shoulder abduction (PMBDT 90°), 2) prone medicine ball drop test 90°shoulder abduction/90° elbow flexion (PMBDT 90°-90°), 3) half-kneeling medicine ball rebound test (HKMBRT), 4) seated single arm shot put test (SSASPT). Measures of systematic bias, absolute reliability and relative reliability were computed between the sessions for both the original test scores and LSI. Results: Except for the SSASPT, all tests demonstrated significant (p ≤ 0.030) improvements in performance during the second session. Generally, for the medicine ball drop/rebound tests, the absolute reliability was the highest (less random error) for the HKMBRT, next the PMBDT 90°followed by PMBDT 90°-90°. Excellent relative reliability existed for the PMBDT 90°, HKMBRT, and SSASPT, whereas fair to excellent relative reliability for the PMBDT 90°-90°. The SSASPT LSI revealed the highest relative and absolute reliability. Conclusion: Two tests, HKMBRT and SSASPT demonstrated sufficient reliability; therefore, the authors' recommend those tests can be used for serial assessments to advance a patient through a rehabilitation program as well as criteria for progression to RTS. Level of Evidence: 3.

A clinician-friendly test battery with a passing rate similar to a 'gold standard' return-to-sport test battery 1 year after ACL reconstruction: Results from a rehabilitation outcome registry.

OBJECTIVES: To 1) present passing rates for different clinician-friendly (CF) test batteries and 2) determine the relationship between passing CF test batteries and passing gold standard (GS) return-to-sport (RTS) muscle function testing, 1 year after ACL reconstruction. STUDY DESIGN: Cross-sectional registry study, level of evidence: 3. SETTING: Primary care. PARTICIPANTS: Data from 588 patients (52% women, mean age 29.3 ± 9.8 years) were extracted from the Project ACL registry. MAIN OUTCOME MEASURES: The passing rates for the different test batteries. RESULTS: The passing rate for GS test battery was 28% (95% CI, 24-32%) and the passing rate for the CF test battery with the lowest passing rate was 27% (95% CI 24-31%). The two CF test batteries with the strongest relationships with passing GS test battery showed that 51% (95% CI 43-59%) and 49% (95% CI 44-55%) of the patients who passed the respective CF test battery also passed the GS test battery. CONCLUSION: A CF test battery can be as demanding to pass as a GS test battery, 1 year after ACL reconstruction. However, passing a CF test battery only gives patients a chance similar to a "coin flip" of also passing a GS RTS test battery.

Quadriceps Strength and Knee-Related Symptom State 6 Months After Anterior Cruciate Ligament Reconstruction.

CONTEXT: Isometric quadriceps strength metrics and patient-reported outcomes are commonly used in return-to-sport assessments in those with anterior cruciate ligament reconstruction (ACLR). Patients may experience clinical knee-related symptoms aggravating enough to seek additional medical care after ACLR. In addition to seeking additional medical care, these patient-reported clinical knee-related symptoms may also influence function after ACLR. However, whether an association exists between these common quadriceps metrics and the patient-reported clinical knee-related symptom state is unknown. OBJECTIVE: To determine if meeting isometric quadriceps strength and symmetry criteria is associated with acceptable clinical knee-related symptoms at 5 to 7 months post-ACLR. DESIGN: Cross-sectional study. SETTING: Laboratories. PATIENTS OR OTHER PARTICIPANTS: We classified individuals at 5 to 7 months post-ACLR based on their isometric ACLR and uninvolved-limb quadriceps strength or quadriceps strength symmetry. We also dichotomized participants based on the Englund et al criteria for unacceptable clinical knee-related symptoms. MAIN OUTCOME MEASURE(S): Quadriceps strength variables were compared between groups using analysis of covariance, and the relative risk of a participant in each quadriceps strength group reporting acceptable clinical knee-related symptoms was determined using binary logistic regression. RESULTS: A total of 173 individuals participated. The isometric quadriceps strength and limb symmetry index were different (P < .001) between quadriceps strength groups. Those categorized as both strong and symmetric had a 1.28 (95% CI = 0.94, 1.74) and individuals categorized as symmetric only had a 1.29 (95% CI = 0.97, 1.73) times greater relative risk of reporting acceptable clinical knee-related symptoms compared with the neither strong nor symmetric group. CONCLUSIONS: The majority of individuals (85%) recovering from ACLR failed to meet either the clinical quadriceps strength or symmetry criteria at 5 to 7 months post-ACLR. Quadriceps strength and quadriceps strength symmetry are clinically important but may not be primary determinants of the clinical knee-related symptom state within the first 6 months post-ACLR.

How limb dominance influences limb symmetry in ACL patients: effects on functional performance.

BACKGROUND: Timing for return to sport (RTS) after anterior cruciate ligament (ACL) injury is paramount for the avoidance of a secondary injury. A common criterion in RTS decision-making is the limb symmetry index (LSI) which quantifies (a)symmetries between the affected and unaffected limb. Limb dominance is one of many factors that may contribute to the recovery of the LSI after ACL reconstruction. The purpose of this study was to examine how limb dominance affects the LSI of functional performance tasks nine months following ACL reconstruction (time of RTS). METHODS: At time of return to sport, n = 100 patients (n = 48 injured the dominant limb, n = 52 injured the non-dominant limb, n = 34 female, n = 66 male) with ACL reconstruction surgery performed isokinetic strength measurements of the knee extensors and flexors, and drop jumps (DJ), single leg hop for distance (SHD) and 6 m timed hop (6MTH) testings. RESULTS: The findings indicated that injury of the dominant leg led to significantly higher LSI values in maximal isokinetic knee extensor strength (p = 0.030). No significant differences were observed for maximal isokinetic knee flexor strength, DJ, SHD or 6MTH performance. Stratifying for sex revealed no significant differences. Simple regression analyses demonstrated that LSI in maximal knee extensor strength significantly predicted LSIs in DJ and SHD while explaining 14% and 18% of the respective variance. CONCLUSIONS: Given that limb dominance affects the LSI of muscle strength suggests that a differentiated interpretation of the LSI with respect to limb dominance should be considered for a safe return to sport. Monoarticular knee extensor strength and multiarticular hop test performance are interrelated and thus can show asymmetries which are not maladaptive but established during years of habituation or training.

Agreement Between Isokinetic Dynamometer and Hand-held Isometric Dynamometer as Measures to Detect Lower Limb Asymmetry in Muscle Torque After Anterior Cruciate Ligament Reconstruction.

Background: Two commonly used instruments to assess muscle strength after anterior cruciate ligament reconstruction are the isokinetic dynamometer, which measures isokinetic torque and the hand-held dynamometer, which measures isometric torque. Isokinetic dynamometers are considered superior to other instruments but may not be commonly used in clinical settings. Hand-held dynamometers are small, portable, and more clinically applicable devices. Purpose: The purpose of this study was to assess agreement between a hand-held dynamometer and an isokinetic dynamometer, used to assess lower limb symmetry in knee muscle torque one year after anterior cruciate ligament (ACL) reconstruction. Study design: Cross-sectional measurement study. Methods: Seventy-two participants who had undergone ACL reconstruction (35 men, 37 women; age= 25.8 ± 5.4 years) were included. Isokinetic muscle torque in knee flexion and extension was measured with an isokinetic dynamometer. Isometric flexion and extension knee muscle torque was measured with a hand-held dynamometer. Bland & Altman plots and Cohen's Kappa coefficient were used to assess agreement between measurements obtained from the instruments. Result: Bland & Altman plots showed wide limits of agreement between the instruments for both flexion and extension limb symmetry index. Cohen´s Kappa coefficient revealed a poor to slight agreement between the extension limb symmetry index values (0.136) and a fair agreement for flexion limb symmetry index values (0.236). Cross-tabulations showed that the hand-held dynamometer detected a significantly larger number of participants with abnormal flexion torque limb symmetry index compared to the isokinetic dynamometer. Conclusion: The wide limits of agreements and Cohen's Kappa coefficients values revealed insufficient agreement between the measurements taken with the two instruments, indicating that the instruments should not be used interchangeably. The hand-held dynamometer was more sensitive in detecting abnormal limb symmetry index in flexion torque, which promotes the option of use of hand-held dynamometers to detect differences between the injured and uninjured leg after ACL reconstruction. Level of evidence: 3b.

A Comparison of Electromyographic Inter-Limb Asymmetry During a Standard Versus a Sling Shot Assisted Bench Press Exercise.

The objective of this study was to compare peak surface electromyography (sEMG) activity of selected muscles along with inter-limb asymmetries between a control (CONT) and a Sling shot assisted (SS) bench press exercise. Ten resistance-trained males with at least three-year experience in resistance training (22.2 ± 1.9 years, 88.7 ± 11.2 kg, 179.5 ± 4.1 cm, bench press one-repetition maximum (1RM) = 127.3 ± 25.9 kg) performed the flat bench press exercise under two conditions at selected loads (85% and 100% of 1RM assessed without the SS). Peak sEMG amplitude of triceps brachii, pectoralis major, and anterior deltoid was recorded for the dominant and the non-dominant side of the body during each attempt. The comparison between the dominant and the non-dominant side was carried out using the limb symmetry index (LSI(%) = (2*(XR - XL)/(XR + XL))*100%) where XR = values of the right side and XL = values of the left side. There was a main effect of condition (p = 0.004; η2 = 0.64) and the load (p = 0.004; η2 = 0.63) for the triceps brachii LSI in parallel with a main effect of condition (p = 0.003; η2 = 0.42) for the anterior deltoid LSI. Post hoc analysis for the main effect of condition showed significant differences in the LSI between the CONT and SS conditions for the triceps brachii (p = 0.003; 1.10% vs. -8.78%) as well as for the anterior deltoid muscles (p = 0.03; 12.91% vs. 9.23%). The results indicate that the assistance of the Sling shot significantly affects the sEMG activity pattern on both the dominant and non-dominant sides of the body while influencing inter-limb asymmetries.

Single-joint Hybrid Assistive Limb in Knee Rehabilitation after ACL Reconstruction: An Open-label Feasibility and Safety Trial.

Objectives: To achieve better outcomes, neuromuscular and biomechanical factors should be considered in rehabilitation after anterior cruciate ligament reconstruction. In this study, we investigated the feasibility and safety of a wearable exoskeleton robot suit [known as the single-joint hybrid assistive limb (HAL-SJ)] and whether knee training using this device could improve functional outcomes after anterior cruciate ligament reconstruction. Methods: HAL-SJ-assisted knee extension and flexion exercises were commenced in 11 patients 18 weeks after reconstruction; exercises were performed once a week for three weeks at a frequency of five sets of ten repetitions. Patients were monitored for HAL-SJ-related adverse events. Physical evaluations were conducted before and after HAL-SJ training. Surface electromyography of the quadriceps and hamstring muscles was performed in 4 of the 11 patients during each session and the muscle co-contraction index was calculated. Results: The peak muscle torque was higher at all velocities after HAL-SJ training. The active range of motion significantly increased in both extension and flexion, and the range of motion in passive flexion significantly increased. The Tegner Activity Scale and Lysholm Knee Questionnaire scores also significantly increased after knee HAL training. The muscle co-contraction index during extension tended to be lower after HAL-SJ training. No adverse events were observed. Conclusions: The findings of this study indicate the feasibility and safety of HAL-SJ training as a neuromuscular rehabilitation tool after anterior cruciate ligament reconstruction. The knee HAL-SJ training may have contributed to these results from a neurophysiological perspective by lowering the co-contraction of knee muscles, which would correct impairment of the antagonistic or synergistic muscles.