Context Anterior cruciate ligament (ACL) injury results in an elevated risk of reinjury despite surgical ACL reconstruction (ACLR). According to the torque-velocity relationship, muscle contraction velocity and torque production should be inversely related, but this is altered following ACLR. Objective To determine the prognostic ability of the torque-velocity relationship to predict future ACL injury in patients recovering from primary ACLR. Design Descriptive laboratory study. Setting Research laboratory. Patients or Other Participants Primary unilateral ACLR patients (n = 579, 50% female), on average, aged 23.5 ± 10.3 years, 1.73 ± 0.10 m, 75.8 ± 17.8 kg, 6.9 ± 2.0 months post-ACLR, participated in this study. Main Outcome Measure(s) Participants completed isokinetic knee extension at 90°/s and 180°/s bilaterally. Peak torque normalized to body mass was used to calculate the torque-velocity relationship. Reinjury outcomes were determined following surgery via follow-up phone calls and medical record reviews with a minimum follow-up time point of 2 years post-surgery. Any subsequent ACL injury to either limb was classified as a reinjury. Results Approximately 14.0% (81/579) of patients suffered reinjury. Reinjury rates were similar by sex ( p = .97) and graft type ( p = .82). A 1 Nm/kg increase in the quadriceps torque-velocity relationship was associated with increased odds of sustaining a reinjury (odds ratio: 3.52; 95% confidence interval (CI) = 1.03, 12.00; p = .045). Each year older participants were was associated with a 6% decrease in reinjury risk (odds ratio: 0.94; 95% CI = 0.91, 0.98; p < .01). Conclusions The quadriceps torque-velocity relationship was predictive of subsequent ACL injury following ACLR and had higher odds of subsequent injury compared with single velocity testing. Increased strength may have influenced return to sport decision making and increased exposure to risk at an earlier point post-ACLR. This may indicate that clinicians should consider increased surveillance of strong young patients and additional modifiable risk factors to enhance reinjury prediction.

INTRODUCTION:Exercise is considered the most effective, non-drug treatment for reducing pain and improving movement in patients with knee osteoarthritis (OA). The current study aimed to compare the efficacy of incorporating a Knee Biofeedback Rehabilitation Game for Osteoarthritis Therapy (KneeBRIGHT) (Barron Associates, Inc., Charlottesville, VA, USA) device into a 10-week rehabilitation course in patients diagnosed with knee OA. METHODS:This clinical trial used a parallel, prospective, single-blind, randomized controlled design. Participants were randomly allocated to the KneeBRIGHT (n = 17) or the control (n = 17) group. Quadriceps muscle strength, perceived knee function using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) scale, and balance were measured prior to and immediately following the rehabilitation program. The KneeBRIGHT group did exercises using the electromyography (EMG)-based video games, while the control group performed the same traditional exercises without the video games. All patients attended a combination of in-clinic and home-based interventions for 10 weeks. Participants were interviewed at the end of the study. RESULTS:Thirty-four patients participated in the study. The KneeBRIGHT group showed an improvement in KOOS quality of life (QOL) (p = 0.002), while the control group demonstrated improvements in KOOS symptoms (p < 0.001), pain (p = 0.009), activities of daily living (ADL; p = 0.005), KOOS sports (p = 0.002), and KOOS QOL (p = 0.016) compared to the baseline. No differences in quadriceps strength were found. The key themes from the interviews indicated that the KneeBRIGHT games are motivating and are an effective alternative to regular exercises. CONCLUSIONS:Patients exhibited improvements in perceived knee function and exhibited increased quadriceps strength using KneeBRIGHT games compared to traditional rehabilitation exercises. Playing video games may help maintain patient motivation and can be done at home independently, effectively reinforcing the therapeutic effect of exercises.

Background:Prognostic indicators of lack of strength progression or poor self-reported function may alter rehabilitation decision-making following anterior cruciate ligament reconstruction (ACLR). The torque-velocity relationship is a noninvasive measure of muscle function that is altered following ACLR, but its prognostic value has not been explored. Purpose:To compare the torque-velocity relationship of knee extensors (quadriceps) and flexors (hamstrings) between the ACLR and uninvolved limbs and to determine whether the torque-velocity relationship was prognostic of subsequent achievement of satisfactory strength. Study Design:Cohort study; Level of evidence, 3. Methods:Participants following ACLR with bone-patellar tendon-bone or hamstring autografts completed isokinetic knee extension and flexion at 90°/s and 180°/s bilaterally, the International Knee Documentation Committee (IKDC) form, and Knee injury and Osteoarthritis Outcome Score (KOOS) at approximately 5.5 and 8.3 months post-ACLR. The torque-velocity relationship was defined as the difference in torque production across velocities, and relationships were analyzed using 2 × 2 analyses of variance. Binomial logistic regressions were used to determine the association between the torque-velocity relationship, age, sex, and time postsurgery with satisfactory knee extension strength, IKDC, and KOOS at visit 2. Results:This study included 189 participants (22.4 ± 9.3 years; 55.0% female). There were significant increases in the quadriceps torque-velocity relationship from visit 1 (0.22 Nm/kg) to visit 2 (0.34 Nm/kg, P < .001) but no differences in the uninvolved limb (P = .46) or for the hamstrings (P = .20). When controlling for sex, age, and graft type, higher visit 1 quadriceps torque-velocity relationships were predictive of a higher likelihood of achieving satisfactory knee extension strength (≥1.23 Nm/kg; odds ratio [OR], 1.05; P = .04). The model was associated with an acceptable IKDC score (≥75.9, P = .01), but the only significant individual predictor was age (OR, 0.94; P < .01). The model was not associated with KOOS Sport score at visit 2 (P = .24). Conclusion:Quadriceps torque-velocity relationships of the ACLR limbs increased across time but remained less than uninvolved limbs. Hamstrings torque-velocity relationships remained similar between limbs and across time. These findings indicate that the torque-velocity relationship of the quadriceps changed over time and was predictive of future satisfactory strength. Clinical Relevance:Clinicians may use a greater quadriceps torque-velocity relationship as a positive indication of a patient's ability to achieve satisfactory strength later in rehabilitation.

INTRODUCTION:The limb symmetry index (LSI) is a common tool for evaluating functional performance across a variety of populations. An LSI of ≥90% is a common, generally accepted clinical threshold for patients with musculoskeletal injuries to achieve before returning to activity. This study's aims were to: (1) describe normative symmetry characteristics and evaluate the influence of sex and limb dominance during functional tasks in healthy, entry-level U.S. Marines, and (2) describe the relationship between symmetry performance across all functional tasks. MATERIALS AND METHODS:This was a cross-sectional study including 651 active duty U.S. Marines with no current injuries (187F/464M, 19.9 ± 2.4 years, limb dominance 59L/592R, 4.8 ± 3.2 months of service). Limb dominance was defined as the preferred limb to kick a soccer ball. Participants completed 5 repetitions of bodyweight bilateral squats and maximal effort vertical jumps using a natural arm swing. Peak eccentric and concentric force (N) were recorded bilaterally on dual force plates for the squat and jump. Participants completed an isometric midthigh pull (IMTP) by standing atop force plates with their knees and hips flexed at approximately 40-50° and 35°, respectively. A fixed bar was positioned at the midpoint between the hips and knees. Participants pulled up as hard and as fast as possible and held a maximal effort for 3-5 seconds for 3 repetitions. Peak vertical force (N) was recorded bilaterally. Force values were normalized to participants' body mass (N/kg). Limb symmetry index was calculated as nondominant limb/dominant limb*100%. Independent sample t-tests determined significant differences in LSI force variables and sexes. Paired t-tests evaluated significant differences in loading between dominant and nondominant limbs. Effect sizes were evaluated via Cohen's d values. Pearson correlations coefficients (r) described the relationship between all dependent variables across all tasks. RESULTS:Across all tasks and variables, there were no differences in LSI values across sexes (P > .05). Regardless of sex, participants loaded more of their body mass on their dominant limb compared to their nondominant limb with weak-to-small effect sizes (d: 0.22-0.34). Squat LSI had a weak-to-moderate positive relationship with LSI during the vertical jump (r: 0.13-0.69). No other significant relationships were observed (P > .05). CONCLUSIONS:Our study provides stakeholders (e.g., military personnel, clinicians, researchers, etc.) normative ranges of LSI performance values during a bodyweight bilateral squat, vertical jump, and IMTP tasks in a large healthy active duty population. Sex does not appear to influence LSI performance; however, limb dominance may influence loading patterns during these specific functional tasks. Given the similarities between the squat and vertical jump performance, future work should be conducted to determine if stakeholders should eliminate one of these tasks from the testing battery to mitigate the temporal burden required when completing functional task assessments in healthy active individuals.

Background: Patient-reported outcome (PROs) instruments of knee function quality of life are routinely administered to patients after anterior cruciate ligament reconstruction (ACLR). The Patient Acceptable Symptom State (PASS), an evidence-based threshold defining perceived outcomes, may be a useful indicator of strength and functional performance. Purpose: To compare strength and functional performance between patients recovering from ACLR who did and did not meet PASS thresholds on associated PROs. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 223 patients who had undergone ACLR (106 women, 117 men; 7.62 ± 1.71 months after ACLR) completed isokinetic knee extensor and flexor strength at 90 deg/s, hop performance (single-limb hop for distance [SLHD], triple hop for distance [THD], 6-m timed hop [6MH]), and PROs (International Knee Documentation Committee Subjective Form [IKDC], Knee injury and Osteoarthritis Outcome Score [KOOS], and Anterior Cruciate Ligament Return to Sport After Injury [ACL-RSI]) assessments in a controlled laboratory setting at an academic institution. Independent-samples t tests compared strength and hop measures between patients who did and did not achieve a PASS on the PROs. Limb symmetry index (LSI) was calculated as (ACLR Limb ÷ Contralateral Limb) × 100%. Strength and hop performance LSI outcomes were converted into indicator variables, categorized as either a “pass” or “fail” based on the operational definition of having an LSI value ≥90%. Chi-square tests compared strength and hop LSI PASS status measures to PRO PASS status. Results: Patients who achieved IKDCPASS were significantly stronger and had more symmetric limbs than those who did not achieve IKDCPASS. Values for IKDCPASS were as follows: knee extension ACLR limb 1.72 ± 0.47 N·m/kg, contralateral limb 2.40 ± 0.45 N·m/kg, LSI 71.64% ± 15.23%; knee flexion ACLR limb 1.04 ± 0.29 N·m/kg, contralateral limb 1.05 ± 0.26 N·m/kg, LSI 99.12% ± 17.22%. Values for IKDCFAIL were knee extension ACLR limb 1.47 ± 0.52 N·m/kg, contralateral limb 2.25 ± 0.47 N·m/kg, LSI 64.66% ± 17.07%; knee flexion ACLR limb 0.88 ± 0.28 N·m/kg, contralateral limb 0.97 ± 0.28 N·m/kg, LSI 90.46% ± 17.41%. Effect sizes ranged from small to moderate ( P < .001; d = 0.3-0.55). IKDCPASS status was significantly associated with an LSI ≥90% for knee flexion peak torque (χ2 = 9.66; P = .002), SLHD (χ2 = 9.61; P = .002), and THD (χ2 = 3.97; P = .02), with a moderate effect size ( P < .05; d = 0.41-0.73). Significant relationships were found with KOOSPASS (Pain, Activities of Daily Living [ADL], and Sport) and LSI ≥90% for peak knee flexion torque with a moderate effect size (Pain and ADL, P < .001; Sport, P = .04; d = 0.59-0.72) and SLHD with a strong effect size for the Symptom subscale (Symptom, P < .01, d = 1.21; Pain, P = .003; ADL, P = .04; Sport, P = .001). No differences were found in strength outcomes for patients who achieved ACL-RSIPASS versus those who did not ( P > .05). Patients who achieved ACL-RSIPASS had more symmetric SLHD and THD LSI scores and jumped farther on their contralateral limb for the THD compared with ACL-RSIFAIL patients ( P < .05; d = 0.50-0.64). Conclusion: Patients meeting thresholds for the IKDCPASS and KOOSPASS (Pain, ADL, and Sport subscales) demonstrated greater knee strength bilaterally, and hopped farther and more symmetrically, compared with patients who scored below the PASS threshold on the same PROs. Using PASS thresholds for PROs can aid clinicians when considering when patients can safely return to activities after ACLR.

BACKGROUND:Considering limb dominance (LD) may be valuable when utilizing limb symmetry index (LSI) when assessing patients after anterior cruciate ligament reconstruction (ACLR). HYPOTHESIS:Patients will have better performance-based outcomes when index ACLR occurred on the dominant limb (DL) compared with the nondominant limb (NDL). STUDY DESIGN:Observational cross-sectional study. LEVEL OF EVIDENCE:Level 3. METHODS:A total of 279 patients (49.1% female, 20.83 ± 5.23 years; 48% DL surgery) completed a laboratory visit (7.65 ± 1.65 months post-ACLR) assessing LD influence on knee extension and flexion peak torque, center of pressure (COP) distance and velocity, and hop performance. LD was defined as the preferred limb to kick a soccer ball. LSI variables were converted to indicator variables and categorized as "Pass" or "Fail" based on LSI ≥ 90%. RESULTS:Patient LD and isometric knee extension LSI Pass status were significantly associated (χ2 = 10.09; P = 0.001). No additional associations were found between LD and other LSI Pass status variables (P > 0.05). Patients with DL ACLR demonstrated more symmetric knee extension peak torque (P < 0.001, d = 0.42) and 6-meter hop (P = 0.02, d = 0.25) outcomes; NDL was more symmetric during COP distance tests (P = 0.03, d = 0.40). No differences were observed between LD and raw strength or balance measures (P > 0.05). Patients with ACLR on their NDL jumped farther on their contralateral limb for triple-hop (P = 0.03, d = 0.23) but not single-hop (P > 0.05) distance. CONCLUSION:LD appears to influence isometric knee LSI in patients post-ACLR; patients with surgery on their DL achieved higher symmetry and a greater rate of LSI Pass success for knee extension strength. CLINICAL RELEVANCE:Addressing differences in recovery patterns between DL and NDL may improve rehabilitation precision and guide return-to-activity timelines after ACLR.

Background:Understanding the role of graft size relative to patellar tendon size for bone-patellar tendon-bone (BTB) autografts may guide presurgical decision making for ACL reconstruction (ACLR). The purpose of this study was to determine the effect of BTB graft size on outcomes following ACLR. We hypothesized that patients with the smaller relative graft size would exhibit the highest strength and function. Methods:Overall, 135 participants approximately 6.8 months post-surgery completed strength testing via isokinetic dynamometer, hop testing, and patient reported outcomes (PROs). Two-year reinjury outcomes were also collected. Preoperative patellar tendon width was determined via MRI, and graft width was measured intraoperatively. Participants were divided based on graft size relative to patellar tendon width into a small percentage group (≤34 %) and large percentage group (>34 %). Results:There were differences in normalized knee extension and flexion at 90°/s (p = 0.02, p < 0.01) and 180°/s (p = 0.001, p = 0.01). When accounting for bilateral differences in strength within subjects, there were no differences in symmetry for strength, functional outcomes or PROs (p = 0.17-0.93). The overall graft rupture rate was 12.6 % and there was no difference in graft rupture rates by graft percentage group (p = 0.32). Conclusion:These findings indicate that the width of patellar tendon grafts relative to patella tendon size has limited effect on outcomes following ACLR. While the small percentage group had higher normalized strength in the involved limb, when accounting for the uninvolved limb via limb symmetry there were no differences in strength. In patients with grafts approximately 10.0-10.6 mm, strength and functional outcomes appear similar.

Context : The landing error scoring system (LESS) was developed to screen healthy individuals for anterior cruciate ligament (ACL) injury risk factors using a jump landing task. The purpose of this study was to evaluate unique landing error components of a modified LESS scoring criteria to determine its clinical utility in patients following ACL reconstruction (ACLR). Design : An observational cross-sectional study design was implemented to determine if each individual error component of the modified LESS provided unique information in an ACLR patient population. Methods : Post-ACLR patients (N = 194 [47.9% female]) completed the LESS 7.91 (1.80) months after surgery. To complete the LESS, patients stood on a 30-cm plyometric box and jumped down to a ground target, at 50% of their height in front of the box, then completed a maximal vertical jump. The LESS was repeated 3 times. Two video cameras positioned 3 m from the landing area at a height of 1 m above the floor (frontal and sagittal) recorded all trials. Video analysis of landing kinematics was performed to determine scores for each error item using the modified LESS. Itemized error scores for each patient were evaluated using an exploratory factor analysis, and factors were retained if eigenvalues were greater than 1. Results : Our exploratory factor analysis yielded 2 factor groupings. The first factor (λ = 1.61) was comprised of 4 biplanar error items (ie, errors that occur in both the frontal and sagittal plane) that evaluated body segment positioning (eg, hip and knee flexion during landing). The second factor (λ = 1.02) was comprised of 2 errors occurring in the frontal plane that evaluated knee valgus and the overall impression of their landing strategy. Conclusions : Reducing the modified LESS errors to 6-items could improve the efficiency and clinical utilization of the LESS in ACLR patients. An abbreviated version of the modified LESS may guide clinicians’ decision making in gauging patients’ readiness to return to play after ACLR.

CONTEXT:Anterior cruciate ligament reconstruction (ACLR) patients commonly adopt poor movement patterns that potentially place them at an increased risk for reinjury if untreated. Limb loading characteristics during functional tasks can highlight movement compensations. OBJECTIVE:To examine loading symmetry during a bilateral bodyweight squatting task between sexes, compare loading metrics between limbs and sexes, and describe the relationship between loading metrics and patient-reported outcomes (PROs) after ACLR. DESIGN:Cross-sectional study. SETTING:Laboratory. PATIENTS OR OTHER PARTICIPANTS:One hundred forty-two patients (71 male, 71 female, age = 24.4 ± 11.10 years) with a primary, unilateral, uncomplicated ACLR completed a squatting assessment and PRO measures at approximately 5.2 months post-ACLR. MAIN OUTCOME MEASURE(S):Normalized limb loading peak force (N/kg) and unilateral cumulative load (%) were collected bilaterally during the squatting task. Limb symmetry index (%) was calculated for normalized peak force. First, we compared limb loading symmetry (%) between sexes using an independent-samples t test. Second, we assessed differences in limb loading metrics between limbs and sexes via an analysis of covariance. Third, we used Spearman ρ correlations to determine the relationship between limb loading metrics and PROs. RESULTS:The majority of individuals (91 of 142, 64.1%) offloaded their ACLR limb (ACLR = 6.6 ± 1.56 N/kg, contralateral = 7.3 ± 1.61 N/kg, P < .001). Females significantly offloaded their ACLR limb (ACLR = 6.3 ± 1.38 N/kg, contralateral = 7.2 ± 1.62 N/kg, P < .001) whereas males did not significantly offload their ACLR limb (ACLR = 6.98 ± 1.65 N/kg, contralateral = 7.4 ± 1.60 N/kg, P = .07). Weak relationships were observed (Ρ value range: -.23 to .19) across limb loading metrics and PROs. CONCLUSIONS:Individuals approximately 5 months after ACLR, on average, offloaded their ACLR limb compared with the contralateral limb. Patients' tendency to offload their weight during a squat was influenced by sex. Relationships between limb loading metrics and PROs indicate patients who load their limbs disproportionately have a lower perception of their capability to complete activities of daily living and lower subjective knee function.

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.

Background: Evidence as to how patient thigh muscle strength and limb loading (LL) during a squatting task recovers throughout rehabilitation after anterior cruciate ligament reconstruction (ACLR) is lacking. Hypothesis: Patients will improve LL and strength throughout rehabilitation. Changes in LL and strength over time will be positively correlated. Study Design: Prospective cohort study. Level of Evidence: Level 3. Methods: A total of 60 participants (28 male/32 female; age, 22.5 ± 9.35 years) participated in 2 visits post-ACLR, assessing LL and strength. Using an instrumented pressure mat, patients completed 3 sets of 3 repetitions of bodyweight squats. Peak force (N), unilateral cumulative load (%), and quadriceps and hamstring isokinetic peak torque (N·m) were calculated and recorded bilaterally. LL and peak torque were compared over time and between limbs. Results: A significant limb-by-time interaction was observed for LL peak force (N), where patients underloaded the ACLR limb at visit 1 compared with the contralateral limb ( P < 0.01). Patients increased their ACLR LL across visits ( P = 0.04). A limb-by-time interaction for quadriceps peak torque (N·m) was observed where the ACLR limb increased peak torque across visits ( P < 0.01); however, strength deficits persisted at visit 2 ( P < 0.01) when compared with the nonoperative limb. Weak correlations were observed between all change scores metrics ( r, 0.20-0.25). Conclusion: Patients recovering from ACLR exhibited more symmetric loading during a squatting task and improved their lower extremity strength over time. Changes in strength were not related to changes in LL during a squatting task over time. Clinical Relevance: Squatting tasks are safe and easily implemented throughout ACLR recovery. As changes in functional LL and strength recovery are not related, both should be considered in serial postoperative testing for more comprehensive function and strength assessments.

CONTEXT:The Balance Error Scoring System (BESS) is a commonly used clinical tool to evaluate postural control that is traditionally performed through visual assessment and subjective evaluation of balance errors. The purpose of this study was to evaluate an automated computer-based scoring system using an instrumented pressure mat compared to the traditional human-based manual assessment. DESIGN:A descriptive cross-sectional study design was used to evaluate the performance of the automated versus human BESS scoring methodology in healthy individuals. METHODS:Fifty-one healthy active participants performed BESS trials following standard BESS procedures on an instrumented pressure mat (MobileMat, Tekscan Inc). Trained evaluators manually scored balance errors from frontal and sagittal plane video recordings for comparison to errors scored using center of force measurements and an automated scoring software (SportsAT, version 2.0.2, Tekscan Inc). A linear mixed model was used to determine measurement discrepancies across the 2 methods. Bland-Altman analyses were conducted to determine limit of agreement for the automated and manual scoring methods. RESULTS:Significant differences between the automated and manual errors scored were observed across all conditions (P < .05), excluding bilateral firm stance. The greatest discrepancy between scoring methods was during the tandem foam stance, while the smallest discrepancy was during the tandem firm stance. CONCLUSION:The 2 methods of BESS scoring are different with wide limits of agreement. The benefits and risks of each approach to error scoring should be considered when selecting the most appropriate metric for clinical use or research studies.

Objective: The purpose of this study was to examine factors correlated with psychological readiness to return to activity after ACLR. Design: cross sectional study. Setting: controlled laboratory. Participants: 164 patients (82 M/82 F, 22.5 +/- 8.9yr, 171.6 +/- 11.0 cm, 77.4 +/- 18.6 kg, 8.6 +/- 3.4 months postACLR) participated in this study after a primary, isolated, and uncomplicated ACLR. Main outcome measures: ACL Return to Sport Index (ACL-RSI). Results: ACL-RSI scores demonstrated a weak positive correlation with activity level at the time of injury and a fair positive correlation with activity level at the time of post-operative testing (p-values: 0.004, <0.001). ACLRSI scores showed a statistically significant fair negative correlation with pain and a moderate negative correlation with kinesiophobia during rehabilitation (p-values: <0.001, <0.001). There was no statistical significance between ACL-RSI and the surgical variables (p-value range: 0.10-0.61). Conclusions: Outcomes from testing during postoperative rehabilitation were most correlated with psychological readiness to return to activity after ACLR. Increased pain and kinesiophobia were associated with a decreased psychological readiness. Increased activity level prior to injury and activity level at the time of testing during rehabilitation were both correlated with increased psychological readiness. Psychological readiness to return to activity may need to be customized based on potentially modifiable patient-specific factors during the postoperative rehabilitation.

Anterior cruciate ligament rupture can negatively alter joint proprioception and balance, thus increasing individuals’ reinjury risk after re-engaging in physical activity. Previous research found no differences in postural stability during single leg (SL) balance with a straight knee position in ACLR (ACL reconstructed) versus healthy participants. PURPOSE: To determine if SL bent knee balance measures differ between healthy and ACLR participants nearing clearance to return to play (RTP). METHODS: Three hundred seventy-four individuals (304 with primary, unilateral, and uncomplicated ACLR and 70 healthy controls) participated (Table 1). Participants performed two, 20-second trials of SL balance on an instrumented pressure mat with their knees flexed to 30°. Trials were standardized starting with the non-surgical limb for ACLR participants and non-dominant limb for healthy participants, procedures were performed bilaterally. Center of pressure (COP) velocity (cm/s) and distance (cm) measures were collected at 60 Hz and averaged across trials within limb. A 2x2 ANOVA (limb-by-group) was used to compared COP velocity and distance in ACLR and healthy participants. Post hoc paired samples t-test were used as appropriate. Alpha level was set at α ≤ 0.05. RESULTS: Descriptive statistics are presented in Table 1. No significant limb-by-group interaction was observed for COP velocity, (F(1,372) = 1.93, p = 0.17) nor distance (F(1,240) = 1.10, p = 0.30). No main effects were found for COP velocity (Limb: F(1,372) = 2.14, p = 0.15; Group: F(1,372) = 0.10, p = 0.75) nor for distance (Limb: F(1,240) = 0.93, p = 0.34; Group: F(1,240) = 0.02, p = 0.88). CONCLUSION: At nearly 6 months ACLR, patients did not exhibit different SL bent knee balance performance compared to healthy controls. Balance measures may not be useful indicators to differentiate outcomes in patients 6 months post ACLR. Future analysis should conduct 2 year follow ups evaluating reinjury status in ACLR patients. - Table 1. Descriptive statistics (Mean ± SD) for participant demographics and postural control for ACLR and Healthy participants. ACLR Healthy n, 374 304 70 Age, Years 23.1 ± 9.9 21.9 ± 3.8 Sex, (Female:Male) 161:143 47:23 Mass, kg 76.6 ± 18.9 70.1 ± 12.2 Height, cm 172.0 ± 10.1 171.4 ± 8.9 Time Post Surgery, Months 6.2 ± 1.4 N/A Current Tegner Activity Scale 5.44 ± 1.71 6.70 ± 1.74 COP Avg. Velocity Surgical/Non-Dominant (cm/s) 4.17 ± 1.15 4.10 ± 1.0 COP Avg. Velocity Non-Surgical/Dominant (cm/s) 4.17 ± 1.17 4.20 ± 1.1 COP Avg. Velocity Limb Symmetry Index (%) 1.01 ± 0.18 0.99 ± 0.17 COP Avg. Distance Surgical /Non-Dominant(cm) 82.4 ± 24.6 80.4 ± 23.8 COP Avg. Distance Non-Surgical/Dominant (cm) 82.3 ± 23.4 83.0 ± 24.6 COP Avg. Distance Limb Symmetry Index (%) 1.01 ± 0.18 0.98 ± 0.17

Objective: To compare patient outcomes at the time of the return to activity (RTA) progression between those with a prior interim assessment and those without.Design: Retrospective, Cohort Study. Setting: Controlled Laboratory. Participants: Patients following Anterior Cruciate Ligament Reconstruction (ACLR) were recruited through an ongoing RTA assessment program. Patients were stratified into two testing groups = "Single RTA test": only assessment between 6 and 9 months post-ACLR and "Repeat RTA test": prior assessment performed >2-months before their RTA assessment. Patients were matched based on time post-surgery, age, activity level, and graft type.Main outcome measure: Self-reported knee function and isokinetic knee flexor and extensor strength/ symmetry were compared between groups.Results: 392 patients were identified. Once matched, 138 patients (21.1 +/- 7.0 years, 7.3 +/- 0 .9 mo post-ACLR) were analyzed. Repeat RTA test patients demonstrated higher measures of self-reported knee function (P = .04) and greater knee flexion strength (P = .006) and symmetry (P = .05).Conclusion: Patients with interim functional assessments reported greater self-reported knee function and higher hamstring strength at the time of RTA compared to patients that completed their only assessment within this time point. Early functional assessments may identify individualized deficits that can be addressed while patients are under supervision of rehabilitation specialists.(c) 2023 Published by Elsevier Ltd.

Background: The inherent nature of the torque-velocity relationship is the inverse nature between the velocity of muscle contraction and torque production and is an indication of muscle function. The purpose of this study was to characterize the torque-velocity relationship in the quadriceps following anterior cruciate ligament recon-struction compared to healthy limbs.Methods: 681 participants were included, 493 of which were patients at least four months following anterior cruciate ligament reconstruction (23.2 & PLUSMN; 10.08 yr, 6.6 & PLUSMN; 5.37 months post-surgery) and 188 were healthy participants (21.6 & PLUSMN; 3.77 yr). A subset of 175 post-surgical participants completed a repeated visit (8.1 & PLUSMN; 1.71 months post-surgery). Participants completed isokinetic knee extension at 90 degrees /s and 180 degrees /s. A one-way ANOVA was used to compare torque velocity relationships by limb type (surgical, contralateral, healthy). Paired samples t-tests were conducted to analyze the torque-velocity relationship across limbs and across time.Findings: There was a large effect for limb type on torque-velocity (F(2, 1173) = 146.08, p < 0.001, & eta;2 = 0.20). Surgical limbs demonstrated significantly lower torque-velocity relationships compared to the contralateral limbs (ACLR: 0.26 Nm/kg, contralateral:0.55 Nm/kg, p < 0.001, d = 1.18). Healthy limbs had similar torque-velocity relationships bilaterally (dominant limb: 0.48 Nm/kg, non-dominant limb: 0.49 Nm/kg, p = 0.45). The torque velocity relationship for the involved limb significantly increased in magnitude over time (+0.11 Nm/kg, p < 0.001, d =-0.61) while the contralateral limb torque-velocity relationship remained stable over time (0.0 Nm/kg difference, p = 0.60).Interpretation: Following surgery, the knee extensors appear to have altered torque-velocity relationships compared to contralateral and healthy limbs. This may indicate a specific target for assessment and rehabilitation following surgery.

Background: Clinical outcomes after revision anterior cruciate ligament reconstruction (ACLR) are not well understood. Hypothesis: Patients undergoing revision ACLR would demonstrate worse patient-reported outcomes and worse limb symmetry compared with a cohort undergoing primary ACLR. Study Design: Cohort study; Level of evidence, 3. Methods: 672 participants (373 with primary ACLR, 111 with revision ACLR, and 188 uninjured) completed functional testing at a single academic medical center. Descriptive information, operative variables, and patient-reported outcomes (International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, and Tegner Activity Scale score) were assessed for each patient. Quadriceps and hamstring strength tests were conducted using a Biodex System 3 Dynamometer. Single-leg hop for distance, triple hop test, and the 6-m timed hop test were also assessed. Limb symmetry index (LSI) between the ACLR limb and contralateral limb was calculated for strength and hop testing. Normalized peak torque (N·m/kg) was calculated for strength testing. Results: No differences were found in group characteristics, excluding body mass ( P < .001), or in patient-reported outcomes. There were no interactions between revision status, graft type, and sex. Knee extension LSI was inferior ( P < .001) in participants who had undergone primary (73.0% ± 15.0%) and revision (77.2% ± 19.1%) ACLR compared with healthy, uninjured participants (98.8% ± 10.4%). Knee flexion LSI was inferior ( P = .04) in the primary group (97.4% ± 18.4%) compared with the revision group (101.9% ± 18.5%). Difference in knee flexion LSI between the uninjured and primary groups, as well as between the uninjured and revision groups, did not reach statistical significance. Hop LSI outcomes were significantly different across all groups ( P < .001). Between-group differences in extension in the involved limb ( P < .001) were noted, as the uninjured group exhibited stronger knee extension (2.16 ± 0.46 N·m/kg) than the primary group (1.67 ± 0.47 N·m/kg) and the revision group (1.78 ± 0.48 N·m/kg). As well, differences in flexion in the involved limb ( P = .01) were found, as the revision group exhibited stronger knee flexion (1.06 ± 0.25 N·m/kg) than the primary group (0.97 ± 0.29 N·m/kg) and the uninjured group (0.98 ± 0.24 N·m/kg). Conclusion: At 7 months postoperatively, patients who had undergone revision ACLR did not demonstrate inferior patient-reported outcomes, limb symmetry, strength, or functional performance compared with patients who had undergone primary ACLR. Patients who had undergone revision ACLR exhibited greater strength and LSI than their counterparts with primary ACLR, but these parameters were still inferior to those of uninjured controls.