Limb preference impacts single-leg forward hop limb symmetry index values following ACL reconstruction

Improved hamstring strength and knee position sense are associated with enhanced landing mechanics after anterior cruciate ligament reconstruction

INTRODUCTION/OBJECTIVES

Return-to-sport decisions after anterior cruciate ligament reconstruction (ACLR) rely on diverse criteria, including neuromuscular performances and functional testing. This study investigates the relationships between neuromuscular parameters, specifically angle-specific strength and proprioception, and knee kinematics during the landing phase of a single-leg hop task in patients 6-12 months post-ACLR.

METHODS

This cohort study included 25 participants (44% women; mean age 28 ± 10 years) who underwent primary ACLR. Demographic and surgical data were collected at 6 weeks postoperatively. Follow-up testing at a mean 8 months post-ACLR included isokinetic assessments of knee extensor and flexor strength to measure peak torques and angle-specific torques, as well as evaluations of position sense. Functional performance was assessed via the single hop for distance (SHD) test, with kinematic analysis of knee flexion during landing. Landing quality was evaluated using the SHD Landing Error Scoring System (SHD-LESS) scale. Multivariate models explored the associations between limb dominance, strength, proprioception and knee kinematics during landing. Correlations between landing quality and patient-reported outcome measures (PROMs), including psychological readiness and self-reported function, were analyzed.

RESULTS

The operated limb exhibited significantly lower strength in knee flexors (p<0.050) and extensors (p<0.001), with the largest deficits observed in angle-specific extensor torque (effect size d > -0.9). No significant limb differences were found in position sense. The operated limb achieved shorter SHD distances (p=0.001) and showed reduced knee flexion at initial contact (p=0.009) and total flexion during landing (p=0.002). Limb dominance influenced initial knee flexion (p=0.018). Greater hamstring strength (p=0.013) and improved position sense (p=0.002) were associated with increased knee flexion during landing. Poor landing mechanics, reflected by SHD-LESS scores, were correlated with impaired position sense (p=0.004) and worse PROMs (p<0.050).

CONCLUSION

Enhancing hamstring strength and position sense may reduce bilateral kinematic discrepancies and improve landing control after ACLR. Limb dominance influences symmetrical kinematics at initial contact. Asymmetrical landing is associated with poorer PROMs, highlighting the importance of assessing both neuromuscular control and functional performances in rehabilitation.

CLINICAL TRIAL REGISTRATION

NCT06524869 LEVEL OF EVIDENCE: III.

Customized Landing Task for ACL Injury Risk Assessment: Kinematic Sex-Related Differences

BACKGROUND

Women present a higher anterior cruciate ligament (ACL) injury rate than men, suggesting sex-related biomechanical differences. Task characteristics are often fixed for both sexes, possibly affecting the perceived difficulty. We investigated kinematic sex differences across landing tasks for ACL injury risk assessment, adjusted to participants' anthropometrics/performance, and whether different tasks affect kinematic sex comparisons.

HYPOTHESIS

Female subjects would exhibit motion patterns more associated with ACL injury risk, and sex-related differences may depend on task type.

STUDY DESIGN

Descriptive laboratory study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 27 female and 29 male amateur players (18-30 years) executed horizontal hop, drop jump (DJ), and DJ followed by vertical or forward jump (length, proportional to maximal forward jump; box, 20% participant's height). An optoelectronic system provided lower limb kinematics at initial contact and peaks until maximum knee flexion (KF), analyzed separately by multivariate analysis of variance (MANOVA) (α = 0.05).

RESULTS

At initial contact, the interaction term had significant effects on hip adduction (P < 0.01) and knee abduction (KAb) (P = 0.04); female participants demonstrated higher KAb (P < 0.01) and knee internal rotation (P = 0.05). For peaks analysis, the interaction term had no significant effects on any individual variable, although significant in MANOVA; female participants had higher KAb (P = 0.01) and lower KF (P = 0.04). Task type affected hip flexion and knee angles in both analyses.

CONCLUSION

All variables in which significant sex-related differences were found are potential ACL injury risk factors, and all findings indicate that the analyzed female sample exhibited higher injury-related patterns. Although customized, male and female participants showed different landing strategies depending on the task.

CLINICAL RELEVANCE

The findings underline how female participants adopted potentially harmful kinematics while executing customized landing tasks (adjusted by subject's anthropometrics/performance), which may enhance risk of ACL injury.

Knee proprioception four months after anterior cruciate ligament reconstruction: Impact of limb dominance, anterolateral procedure, and association with readiness to return to sport

BACKGROUND

Knee proprioception may be compromised after anterior cruciate ligament reconstruction (ACLR), but associated factors and impact remain unclear. This study evaluated knee proprioception 4 months after primary ACLR, compared with healthy controls, and explored the impacts of leg dominance, anterolateral procedures (AEAPs), and their association with psychological readiness to return to sports.

METHODS

This prospective cohort study included 30 ACLR participants and 20 healthy controls. Isokinetic testing measured knee strength and proprioception, using passive joint position sense (JPS1: detection, JPS2: repositioning) and kinesthesia (threshold to detection of passive motion). At 8 months, ACLR participants completed the ACL-RSI scale to assess psychological readiness to return to sports.

RESULTS

At 4 months postoperative, kinesthesia was better in the operated limb than the non-operated limb (p = 0.008), but position sense did not differ significantly. There were no significant differences in kinesthesia or position sense between ACLR participants and controls. The operated limb had worse JPS2 if the ACLR was on the non-dominant side. Proprioception was unaffected by AEAPs, and only repositioning showed a moderate, non-significant correlation with ACL-RSI (r = -0.377).

CONCLUSION

At 4 months post-ACLR, kinesthesia improved in the operated leg; dominance influenced position sense, highlighting the need for personalized rehabilitation.

Associations Between Race and Socioeconomic Status, Lower Extremity Strength, and Patient-Reported Outcomes Following Anterior Cruciate Ligament Reconstruction

CONTEXT

There are significant disparities in access to health care, but there are limited data about the impact of race and socioeconomic status on postoperative outcomes following anterior cruciate ligament reconstruction (ACLR) surgery.

OBJECTIVE

To identify associations between the Area Deprivation Index (ADI), strength measures, and patient-reported outcomes following ACLR and examine differences in outcomes between race, sex, and socioeconomic status.

DESIGN

Case-control study in a single hospital setting.

SETTING

Database secondary analysis.

PATIENTS OR OTHER PARTICIPANTS

Data were collected from 340 patients who underwent primary, isolated, unilateral ACLR.

MAIN OUTCOME MEASURE(S)

Strength measures and patient-reported outcomes were obtained at patients' postoperative assessments at approximately 6 months postsurgery. Area Deprivation Index values were calculated on each patient's census tract, as determined through medical records review. Correlations were conducted to determine the relationship between the ADI and Knee Injury and Osteoarthritis Outcome Score measures, International Knee Documentation Committee, and limb symmetry on strength measurements. The racial composition of the sample was heavily skewed and was excluded from statistical analyses.

RESULTS

The ADI was weakly correlated with International Knee Documentation Committee (ρ = 0.11, P = .04) outcomes, with more disadvantaged patients reporting better quality of life and knee function. The ADI was not correlated with other outcomes of interest. The median ADI value of the sample was 32 (range, 1-86 [interquartile range, 19-47]).

CONCLUSIONS

Our study revealed a weak correlation between higher levels of socioeconomic disadvantage as measured by the ADI and improved subjective assessment of knee function and quality of life as measured by International Knee Documentation Committee. These findings are contrary to what other studies on this subject have found and highlight the importance of further research into the impact of socioeconomic status and other social determinants of health on post-ACLR outcomes.

Limb dominance influences landing mechanics and neuromuscular control during drop vertical jump in patients with ACL reconstruction

Objectives

The purpose of this study was to compare the interlimb biomechanical differences in patients who had undergone anterior cruciate ligament reconstruction (ACLR) in either dominant (ACLR-D) or nondominant (ACLR-ND) limbs and healthy controls (CON) during drop vertical jump (DVJ) task. To investigate whether the dominant or nondominant limb influences the risk of re-injury in ACLR patients.

Methods

Thirty-three ACLR patients were divided into ACLR-D and ACLR-ND groups according to whether the surgical limb was dominant or nondominant. Seventeen healthy individuals were selected as the CON group. Three-dimensional kinematic data, ground reaction force (GRF) data, and surface electromyographic (EMG) data from the bilateral lower limbs of all participants were collected during the DVJ task. Two-way repeated-measures ANOVAs (limb × group) were performed on the variables of interest to examine the main effects of limb (dominant vs. nondominant) and group (ACLR-D, ACLR-ND, and CON), as well as the interaction between limb and group.

Results

The nonsurgical limbs of ACLR group had significantly greater knee valgus angles, knee extension and valgus moments, peak posterior GRF (PPGRF), and peak vertical GRF (PVGRF) compared to the surgical limbs. The nonsurgical limbs of ACLR-ND patients demonstrated significantly greater knee extension and valgus moments, greater PPGRF and PVGRF, and reduced muscle activity in the vastus medialis and vastus lateralis compared to the CON group. The ACLR patients had reduced muscle activity in the quadriceps of the surgical limb and the hamstrings of the bilateral limbs compared to controls.

Conclusion

The nonsurgical limbs of ACLR patients may suffer an increased risk of ACL injury due to altered landing mechanics and neuromuscular control strategies compared to the surgical limbs. Additionally, limb dominance influences movement patterns and neuromuscular control during DVJ task, the nonsurgical limbs of the ACLR-ND might be at higher risk of ACL injury compared to the ACLR-D group.

Predicting the Recovery of Isokinetic Knee Strength 6 Months After Anterior Cruciate Ligament Reconstruction

Background

The limb symmetry index (LSI) is a metric of strength restoration. It is key to successfully return to sports after anterior cruciate ligament (ACL) reconstruction. The threshold for return to sports is generally considered an LSI of ≥85%.

Purpose

To develop a statistical model for predicting the recovery of knee extension and flexion strength (with LSI ≥85%) at 6 months after ACL reconstruction.

Study Design

Case-control study; Level of evidence: 3.

Methods

Patients who underwent arthroscopic ACL reconstruction between November 2015 and December 2020 were included. The patients were classified into 2 groups: "pass" if the LSI at 6 months postoperatively was ≥85% and "fail" if the LSI was <85%. Factors in 25 categories with 74 levels, including patient characteristics, periarticular procedures, intra-articular lesions and treatment, and perioperative management, were collected. A multivariable logistic regression combined with backward variable elimination was used to determine the predictive parameters for recovery of knee extension and flexion strength.

Results

A total of 948 patients were included. Graft site, preoperative isokinetic strength, treatment of meniscal injury, and injured side (left vs right) were identified as general predictors for both knee extension and flexion strength. For knee extension strength, age at injury and partial weightbearing duration were identified as additional predictors. For knee flexion strength, type of meniscal injury, surgeon volume, cartilage procedures, and periarticular procedures were identified as additional predictors. The Nagelkerke R 2 of the final model was 0.178, and the c-statistic was 0.716 (95% CI, 0.676-0.754). The Hosmer-Lemeshow test indicated good calibration (P = .879).

Conclusion

Several factors including preoperative isokinetic strength, treatment of meniscal injuries, left vs. right side and graft site were found to predict recovery of ≥85% LSI in knee extension and flexion strength. Despite the numerous factors that were analyzed, the predictive power was moderate (c-statistic = 0.716), indicating there were other nonincluded factors that significantly influence strength performance at 6 months postoperatively.

Double-Leg and Single-Leg Jump Test Reference Values for Athletes With and Without Anterior Cruciate Ligament Reconstruction Who Play Popular Pivoting Sports, Including Soccer and Basketball: A Scoping Review

OBJECTIVE: To synthesize and present reference values for double-leg and single-leg jump tests in healthy athletes who play pivoting sports, and athletes with anterior cruciate ligament reconstruction (ACLR) who play pivoting sports. DESIGN: Scoping review. LITERATURE SEARCH: We searched PubMed, the Cochrane Library, MEDLINE, Embase, and Web of Science until April 7, 2023. STUDY SELECTION CRITERIA: We included reference values in 2 different categories: (1) double-leg and/or single-leg jump test outcomes in pivoting-sport athletes with ACLR at a specific time point during rehabilitation, and (2) double-leg and/or single-leg jump test outcomes in healthy pivoting-sport athletes. DATA SYNTHESIS: We performed data synthesis for reference values from double-leg jump tests (squat jump and countermovement jump) and single-leg jump tests (vertical hop, single hop for distance, triple hop for distance, crossover hop for distance, medial triple hop for distance, lateral triple hop for distance, 6-m timed hop, side hop, drop jump, and 10-second repeated hop) that were performed according to a standardized test description. We summarized the data for type of sport, sex, sport participation level, and age group. RESULTS: Of the 27 included studies, nine reported reference values from healthy soccer players, six from healthy basketball players, and eleven from other healthy pivoting-sport athletes. LSI dominant/nondominant (LSI-D/ND) ranged between 97% and 106% for healthy soccer players, and between 99% and 120% for healthy basketball players. Four studies reported reference values from pivoting-sport athletes with ACLR from 7 to 10 months postsurgery. CONCLUSION: This scoping review summarizes double-leg and single-leg jump test reference values for athletes who play common pivoting sports, including soccer and basketball. J Orthop Sports Phys Ther 2024;54(6):1-14. Epub 20 March 2024. doi:10.2519/jospt.2024.12374.