The Influence of Strength and Sport Exposure on Psychological Readiness After ACL Reconstruction.

BACKGROUND: Among young athletes returning to sport after anterior cruciate ligament reconstruction (ACLR), the extent to which psychological readiness is influenced by factors beyond the psychological domain is largely unknown. HYPOTHESIS: Young athletes with recent sport exposure and higher quadriceps strength will demonstrate higher psychological readiness within 8 weeks of medical clearance to return to sport (RTS) after ACLR. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 38 young athletes after primary ACLR completed testing within 8 weeks of medical clearance to RTS. All participants completed isometric knee extension strength testing, in addition to the ACL Return to Sport after Injury (ACL-RSI) questionnaire. Athletes who participated in sport between time of medical clearance to RTS and date of study enrollment were categorized as SPORT-YES. Those who had not yet participated in sports were categorized as SPORT-NO. Multiple linear regression analyses were used to determine differences in ACL-RSI scores based on quadriceps strength and sport exposure status, while adjusting for age and sex. RESULTS: Of the 38 participants, 20 (52.6%) were categorized as SPORT-YES. The regression model estimating overall ACL-RSI score (P < 0.01, adjusted R2 = 0.389) included significant independent contributions from age, sex, and sport exposure variables (age: P = 0.01, ß [95% CI] = -2.01 [-3.54, -0.48]; sex (male): P = 0.02, ß [95% CI] = 12.50 [2.36, 22.64]; strength: P = 0.51, ß [95% CI] = -2.47 [-10.07,5.13]; sport exposure: P < 0.01, ß [95% CI] = 12.89 [3.58, 22.19]). CONCLUSION: In partial accordance with our hypothesis, recent sport exposure was significantly associated with higher ACL-RSI scores among young athletes in the weeks after medical clearance to RTS after ACLR, while quadriceps strength was not. CLINICAL RELEVANCE: Future prospective work is needed to determine the existence and direction of causal relationships between exposure to sport environment and psychological readiness among young athletes after ACLR.

The Association of Physical Competence With Psychological Response Among Young Athletes at Time of Return to Sport After ACL Reconstruction.

BACKGROUND: The traditional index of return-to-sport (RTS) readiness after anterior cruciate ligament reconstruction (ACLR) is the achievement of physical competence criteria. Emerging research indicates that psychological response and self-perceptions of physical competence may be critical mechanisms for successful RTS among young athletes. HYPOTHESIS: Young athletes with higher actual physical competence (APC) and perceived physical competence (PPC) will demonstrate a more positive psychological response at the time of RTS after ACLR. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 41 young athletes after primary ACLR completed testing within 8 weeks of medical clearance to RTS. APC was measured with isokinetic knee extension strength, single-limb crossover hop for distance, and the Knee injury and Osteoarthritis Outcome Score. PPC was measured with the Athletic Competence subscale of the Self-Perception Profile. Criteria for APC and PPC were based on established age- and activity-relevant cutoff scores. Different constructs of psychological response were assessed with the adapted Sport Motivation Scale, Brief Resilience Scale, and Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) total and subscale scores (Emotions, Confidence, and Risk Appraisal). Multiple linear regression analyses were used to determine differences in measures of psychological response based on achievement of APC and PPC, while adjusting for age and sex. RESULTS: Of the 41 participants, 10 (24.4%) met all criteria for APC and 22 (53.7%) met the PPC criteria. The regression models estimating the ACL-RSI score (P < .001; adjusted R2 = 0.331), ACL-RSI Emotions score (P < .001; adjusted R2 = 0.427), and ACL-RSI Risk Appraisal score (P = .013; adjusted R2 = 0.212) were statistically significant. Although APC was not associated with any measure of psychological response, meeting PPC criteria, younger age, and male sex were found to be associated with a more positive psychological readiness to RTS, but not with motivation or resilience. CONCLUSION: Meeting PPC criteria was associated with higher psychological readiness to RTS among young athletes after ACLR, while meeting APC criteria was not associated with any construct of psychological response.

Preventing Osteoarthritis After an Anterior Cruciate Ligament Injury: An Osteoarthritis Action Alliance Consensus Statement.

After an anterior cruciate ligament (ACL) injury, people need secondary prevention strategies to identify osteoarthritis at its earliest stages so that interventions can be implemented to halt or slow the progression toward its long-term burden. The Osteoarthritis Action Alliance formed an interdisciplinary Secondary Prevention Task Group to develop a consensus on recommendations to provide clinicians with secondary prevention strategies that are intended to reduce the risk of osteoarthritis after a person has an ACL injury. The group achieved consensus on 15 out of 16 recommendations that address patient education, exercise and rehabilitation, psychological skills training, graded-exposure therapy, cognitive-behavioral counseling (lacked consensus), outcomes to monitor, secondary injury prevention, system-level social support, leveraging technology, and coordinated care models. We hope this statement raises awareness among clinicians and researchers on the importance of taking steps to mitigate the risk of osteoarthritis after an ACL injury.

Predictions of total work based on measures of muscle strength and hop performance in individuals after ACL reconstruction.

OBJECTIVES: The purpose of this study was to determine the ability to utilize clinical measures of hop performance and thigh muscle strength to predict total limb work, a measure of cumulative single leg power, in young athletes at the time of return to sport after ACLR. We hypothesized that hop test performance and thigh muscle strength would predict total limb work during a maximal effort repeated vertical single-leg jump and that hop test performance would better predict total limb work during a maximal effort repeated vertical single-leg jump than measures of thigh strength. DESIGN: Cross-sectional study. PARTICIPANTS: Analysis on data from 50 individuals after unilateral ACLR (74% women, age 14-23 years) MAIN OUTCOME MEASURES: Performed 10-s repeated vertical single-leg jump test on a force platform where single limb power and resultant total work were calculated. At the same session, participants completed a clinical single leg hop test battery and thigh strength testing. RESULTS: All clinical measures were associated with total work during the repeated vertical single-leg jump test on the involved and uninvolved limbs, respectfully. After controlling for height and weight, quadriceps femoris peak torque at 180°/s was the strongest predictor of total work for both limbs. On the involved limb, performance on the triple hop test for distance also uniquely contributed to the prediction of total work. CONCLUSIONS: Quadriceps femoris muscle strength and distance hop test performance predict total limb work capacity of the involved limb during a single-leg dynamic task. Optimizing both measures after ACLR may positively impact vital components of sports performance.

Accelerated rehabilitation program following medial patellofemoral ligament reconstruction does not increase risk of recurrent instability.

BACKGROUND: Rehabilitation protocols following medial patellofemoral ligament (MPFL) reconstruction were historically restrictive, with patients often immobilized and/or given weightbearing restrictions. However, more recently published protocols have been more aggressive. We compared patient-reported outcomes and recurrent dislocation risk between patients treated with a restrictive rehabilitation program (early post-operative bracing and weightbearing restrictions) and an accelerated rehabilitation protocol (no post-operative bracing or weightbearing restrictions) following MPFL reconstruction. METHODS: Patients who underwent isolated MPFL reconstruction at an academic center between 2008 and 2016 were identified. Patient demographics, anatomical measurements, surgical details, and outcomes were collected. During this period, the rehabilitation protocol at the center transitioned from a restrictive to an accelerated rehabilitation protocol. Failure risk and patient-reported outcomes were compared based on rehabilitation protocol. RESULTS: Of the163 isolated MPFL reconstructions performed during the study period, 123 (75%) were available for minimum one-year follow up at a mean of 4.0 years post-operative. Overall, 53 knees (43%) underwent the accelerated rehabilitation protocol and the remaining 70 knees (57%) underwent the restrictive protocol. There were 3 recurrent dislocations during the study period (2.4%), all of which occurred in the restrictive rehabilitation group. Multiple linear regression demonstrated that being in the accelerated rehabilitation group was not associated with poorer Knee injury and Osteoarthritis Outcome Score (KOOS) subscales controlling for age, sex, body mass index, Caton-Deschamps Index, tibial tubercle-trochlear groove distance, sulcus angle, MPFL graft choice, and length of follow-up. CONCLUSION: An accelerated rehabilitation protocol without immobilization or weightbearing restrictions does not increase risk of recurrent patellar dislocation or poorer patient-reported outcome following isolated MPFL reconstruction.

The effects of knee osteoarthritis on neural activity during a motor task: A scoping systematic review.

OBJECTIVE: To examine the evidence of neural activation with functional magnetic resonance imaging (fMRI), corticospinal excitability, and other central nervous system measurement differences during motor tasks between those with and without knee osteoarthritis (KOA). METHODS: A scoping review strategy was systematically performed. We searched PubMed, CINAHL, Embase, PsychInfo, SportDiscus, SCOPUS and Web of Science from database inception to April 2021. Any study investigating central nervous system measures during a motor task for individuals with KOA with or without a healthy control group for comparison was included. Two reviewers independently screened all studies in accordance with the Preferred Reported Items for Systematic Reviews and Meta-analyses extension for scoping reviews. RESULTS: Thirteen studies met the inclusion criteria. KOA had reduced activation of the premotor cortex during a gait imagery task when examining the brain using fMRI. This hypoactivation was not significant when the task was combined with ankle movement. Individuals with KOA had decreased motor cortex activation during a force matching motor task. KOA was associated with gamma loop dysfunction of the quadriceps and increased responsiveness of the triceps surae muscles. Also, there was an increased soleus Hoffmann reflex during heel strike of gait cycle. The flexor withdrawal reflex was heighted for individuals with KOA with a lower threshold of the reflex occurring with increased joint compression, but this reflex was modulated with joint mobilizations. CONCLUSION: Individuals with KOA have motor deficits associated with decreased neural activation, central nervous system sensitization, decreased quadriceps muscle spindle responsiveness, and increased triceps surae muscle activity.

Is modular control related to functional outcomes in individuals with knee osteoarthritis and following total knee arthroplasty?

BACKGROUND: Individuals who undergo total knee arthroplasty (TKA) for treatment of knee osteoarthritis often experience suboptimal outcomes. Investigation of neuromuscular control strategies in these individuals may reveal factors that contribute to these functional deficits. The purpose of this pilot study was to determine the relationship between patient function and modular control during gait before and after TKA. METHODS: Electromyography data from 36 participants (38 knees) were collected from 8 lower extremity muscles on the TKA-involved limb during ≥5 over-ground walking trials before (n = 30), 6-months after (n = 26), and 24-months after (n = 13) surgery. Muscle modules were estimated using non-negative matrix factorization. The number of modules was determined from 500 resampled trials. RESULTS: A higher number of modules was related to better performance-based and patient-reported function before and 6-months after surgery. Participants with organization similar to healthy, age-matched controls trended toward better function 24-months after surgery, though these results were not statistically significant. We also observed plasticity in the participants' modular control strategies, with 100% of participants who were present before and 24-months after surgery (10/10) demonstrating changes in the number of modules and/or organization of at least 1 module. CONCLUSIONS: This pilot work suggests that functional improvements following TKA may initially present as increases in the number of modules recruited during gait. Subsequent improvements in function may present as improved module organization. NOTEWORTHY: This work is the first to characterize motor modules in TKA both before and after surgery and to demonstrate changes in the number and organization of modules over the time course of recovery, which may be related to changes in patient function. The plasticity of modular control following TKA is a key finding which has not been previously documented and may be useful in predicting or improving surgical outcomes through novel rehabilitation protocols.

Discover your potential: The influence of kinematics on a muscle's ability to contribute to the sit-to-stand transfer.

Existing methods for estimating how individual muscles contribute to a movement require extensive time and experimental resources. In this study we developed an efficient method for determining how changes to lower extremity joint kinematics affect the potential of individual muscles to contribute to whole-body center-of-mass vertical (support) and anteroposterior (progression) accelerations. A 4-link 2-dimensional model was used to assess the effect of kinematic changes on muscle function. Joint kinematics were systematically varied throughout ranges observed during the momentum transfer phase of the sit-to-stand transfer. Each muscle's potential to contribute to support and progression was computed and compared to simulated potentials estimated by traditional dynamic simulation methods for young adults and individuals with knee osteoarthritis. The new method required 4-10s to compute muscle potentials per kinematic state and computed potentials were consistent with simulated potentials. The new method identified differences in muscle potentials between groups due to kinematic differences, particularly decreased anterior pelvic tilt in young adults, and revealed kinematic and muscle strengthening modifications to increase support. The methods presented provide an efficient, systematic approach to evaluate how joint kinematic adjustments alter a muscle's ability to contribute to movement and can identify potential sources of pathologic movement and rehabilitation strategies.

Return-to-Sport Criteria After Anterior Cruciate Ligament Reconstruction Fail to Identify the Risk of Second Anterior Cruciate Ligament Injury.

BACKGROUND: The incidence of second anterior cruciate ligament (ACL) injury after ACL reconstruction (ACLR) is high in young, active populations. Failure to successfully meet return-to-sport (RTS) criteria may identify adult athletes at risk of future injury; however, these studies have yet to assess skeletally mature adolescent athletes. OBJECTIVE: To determine if failure to meet RTS criteria would identify adolescent and young adult athletes at risk for future ACL injury after ACLR and RTS. The tested hypothesis was that the risk of a second ACL injury after RTS would be lower in participants who met all RTS criteria compared with those who failed to meet all criteria before RTS. DESIGN: Prospective case-cohort (prognosis) study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 159 individuals (age = 17.2 ± 2.6 years, males = 47, females = 112). MAIN OUTCOME MEASURE(S): Participants completed an RTS assessment (quadriceps strength, functional hop tests) and the International Knee Documentation Committee patient survey (0 to 100 scale) after ACLR and were then tracked for occurrence of a second ACL tear. Athletes were classified into groups that passed all 6 RTS tests at a criterion level of 90% (or 90 of 100) limb symmetry and were compared with those who failed to meet all criteria. Crude odds ratios and 95% CIs were calculated to determine if passing all 6 RTS measures resulted in a reduced risk of second ACL injury in the first 24 months after RTS. RESULTS: Thirty-five (22%) of the participants sustained a second ACL injury. At the time of RTS, 26% achieved ≥90 on all tests, and the remaining athletes scored less than 90 on at least 1 of the 6 assessments. The second ACL injury incidence did not differ between those who passed all RTS criteria (28.6%) and those who failed at least 1 criterion (19.7%, P = .23). Subgroup analysis by graft type also indicated no differences between groups (P > .05). CONCLUSIONS: Current RTS criteria at a 90% threshold did not identify active skeletally mature adolescent and young adult athletes at high risk for second ACL injury.

Identification and Predictors of Age-Relevant and Activity-Relevant Hop Test Targets in Young Athletes After Anterior Cruciate Ligament Reconstruction.

CONTEXT: Performance symmetry between limbs (limb symmetry index [LSI] ≥ 90%) on a battery of single-leg hop tests is recommended to inform return-to-sport (RTS) decisions after anterior cruciate ligament (ACL) reconstruction (ACLR). Achieving current hop test symmetry values has not been associated with future clinical outcomes. The identification of age-relevant and activity-relevant target values to benchmark the hop test performance of young athletes post-ACLR may provide greater specificity and clinical relevance for interpretation of hop test data. OBJECTIVE: To identify single-leg hop test-target values for individual-limb performance and symmetry between limbs for athletes without a history of ACL injury and evaluate the proportion of young athletes post-ACLR who met the newly derived target values at the time of RTS clearance. The secondary objective was to test the hypothesis that better function and strength would be associated with achieving the newly derived hop test target values. DESIGN: Cross-sectional study. SETTING: Pediatric medical center and academic medical center. PATIENTS OR OTHER PARTICIPANTS: A total of 159 young athletes (age = 16.9 ± 2.2 years) at the time of RTS clearance after primary, unilateral ACLR and 47 uninjured control athletes (age = 17.0 ± 2.3 years). MAIN OUTCOME MEASURE(S): All participants completed a single-leg hop test battery (single hop, triple hop, and crossover hop for distance [cm], and 6-m timed hop [seconds]). Raw distance values were normalized by body height, and LSI (%) was calculated for each hop test. Target values were defined as the lower bound of the 95% CI for each hop test, using control group data. Participants with ACLR also completed the Knee injury and Osteoarthritis Outcome Score subscales and a quadriceps femoris strength (newton meters/kilogram) assessment. Logistic regression determined predictors of achieving hop test target values in the ACLR group among injury, function, and strength data (P < .05). RESULTS: In the ACLR group, 79% to 84% of participants met the 90% LSI threshold on each hop test. They achieved the target values for surgical-limb performance in the following proportions (% participants): single hop = 29%, triple hop = 24%, crossover hop = 30%, 6-m timed hop = 18%, all hops= 12%. Also, they met the target values for LSI in the following proportions: single hop = 43%, triple hop = 48%, crossover hop = 50%, 6-m timed hop = 69%, all hops = 25%. The only predictor of achieving all hop test targets for surgical-limb performance was greater surgical-limb quadriceps femoris strength (odds ratio = 4.10, P = .007). We noted a trend toward quadriceps femoris strength LSI ≥ 90% (odds ratio = 2.44, P = .058) as a predictor for meeting all hop test symmetry targets. CONCLUSIONS: At the time of RTS post-ACLR, only a small proportion of young athletes achieved the age-relevant and activity-relevant single-leg hop test targets for surgical-limb performance or symmetry between limbs, even though a majority met the traditionally recommended 90% LSI threshold on hop tests.

Few young athletes meet newly derived age- and activity-relevant functional recovery targets after ACL reconstruction.

PURPOSE: National registry data have established Knee injury and Osteoarthritis Outcome Score (KOOS) functional recovery target values for adults after anterior cruciate ligament (ACL) reconstruction. However, the specificity of these target values for young athletes after ACL reconstruction is unclear. The purpose of this analysis was to (1) derive age- and activity-relevant KOOS functional recovery target values from uninjured young athlete data and (2) determine clinical measures at the time of RTS clearance associated with meeting the newly-derived functional recovery target values in young athletes following ACLR. METHODS: Two hundred and twenty-two young athletes (56 uninjured controls, 17.2 ± 2.4 years, 73% female; 166 after ACL reconstruction, 16.9 ± 2.2 years, 68% female) were included in this cross-sectional analysis from a larger cohort study. Uninjured control participants completed the KOOS, and functional recovery target values were defined as the lower bound of the 95% confidence interval for KOOS subscales. ACL reconstruction participants completed testing within 4 weeks of return-to-sport clearance, including the KOOS, single-leg hop tests, and isometric quadriceps strength. In ACL reconstruction participants, logistic regression was used to determine predictors of meeting all KOOS functional recovery target values (primary outcome) among demographic/injury, hop, and strength data (α ≤ 0.05). RESULTS: KOOS functional recovery target values for each subscale from uninjured athlete data were: Pain ≥ 94, Symptoms ≥ 92, Activities of Daily Living ≥ 97, Sport ≥ 92, and Quality-of-Life ≥ 92. At the time of return-to-sport clearance, ACL reconstruction participants met the KOOS functional recovery targets in the following proportions: Pain, 63%; Symptoms, 42%; Activities of Daily Living, 80%; Sport, 45%; Quality-of-Life, 24%; overall functional recovery (met all subscale targets), 17%. In ACL reconstruction participants, significant predictors of overall functional recovery (primary outcome) were: younger age, hamstring graft, pediatric ACL reconstruction, quadriceps strength limb-symmetry index > 90%, single-hop limb-symmetry index > 90%, and crossover-hop limb-symmetry index > 90%. CONCLUSIONS: KOOS functional recovery target values derived from uninjured young athletes were higher than those previously reported. Small proportions of young athletes following recent RTS clearance after ACLR met these newly-derived functional recovery target values, and factors associated with meeting functional recovery target values included younger age, hamstring autograft and pediatric ACLR, and having > 90% LSI for quadriceps strength and single-leg hop tests. LEVEL OF EVIDENCE: I.

Confidence, ability to meet return to sport criteria, and second ACL injury risk associations after ACL-reconstruction.

This study tested the hypotheses that participants with high knee-related confidence at the time of return to sport (RTS) after anterior cruciate ligament (ACL) reconstruction (ACLR) would have a greater likelihood of meeting RTS criteria and would have a higher likelihood of second ACL injury. Participants completed RTS testing when cleared to RTS. Success was defined as an IKDC score more than or equal to 90 and all limb symmetry index (LSI) scores more than or equal to 90%. Confidence groups were created based on response to the KOOS Quality of Life subscale. Incidence of second ACL injury was tracked for 24 months after RTS. Associations among confidence, success in meeting RTS criteria, and second ACL injury were evaluated. At RTS, 37.7% were classified with high knee-related confidence, 26.4% met RTS criteria and 22.0% sustained a second ACL injury post-RTS. A higher proportion of confident participants met all RTS criteria (p = 0.001). Confident participants were over two times more likely to suffer a second ACL injury (odds ratio [OR] = 2.40; 95% confidence interval [CI]:1.21-5.20) (p = 0.02) and participants who were both confident and met all RTS criteria were 10 times more likely to suffer a second ACL injury (OR = 9.6; 95% CI:1.1, 84.2) (p = 0.02) than those who passed all RTS criteria but lacked knee-related confidence. Clinical significance: Confident, young athletes at the time of RTS after ACLR are more likely to meet all RTS criteria and more likely to sustain a second ACL injury after RTS. Future work must consider how the inclusion of additional factors into RTS criteria may better identify those at high risk for poor outcome after ACLR.

Passing return-to-sport criteria and landing biomechanics in young athletes following anterior cruciate ligament reconstruction.

We sought to evaluate the sagittal plane knee joint loading patterns during a double-leg landing task among young athletes who passed or failed return-to-sport (RTS) criteria following anterior cruciate ligament reconstruction reconstruction (ACLR), and in uninjured athletes. Participants completed quadriceps strength testing, a hop test battery, and the International Knee Documentation Committee subjective form following medical RTS clearance. ACLR participants "passed" RTS criteria (RTS-PASS) if they met ≥90 limb symmetry (%) or score on all measures and were categorized as "failing" (RTS-FAIL) if not. All participants completed three-dimensional motion analysis testing. Sagittal plane kinematic and kinetic variables were calculated during a double-leg drop vertical jump task. Mean limb values and limb symmetry indices (LSI; %) were calculated and compared using a one-way analysis of variance (ANOVA) (for LSI) and mixed between-within ANOVA (for group × limb differences). A total of 205 participants were included, with 39 in the RTS-PASS group, 109 in the RTS-FAIL group, and 57 control groups (CTRLs). The RTS-FAIL group demonstrated lower symmetry values for peak vertical ground reaction force, peak internal knee extension moment, and peak knee flexion angle. Group × limb interactions were observed for peak vertical ground reaction force and peak internal knee extension moment. Involved limb values were reduced in the RTS-PASS and RTS-FAIL groups compared to CTRLs, while the RTS-PASS groups had lower uninvolved limb values compared to the RTS-FAIL and CTRLs. Clinical Significance: Young athletes who pass RTS criteria after ACLR land symmetrically during a double-leg task, but symmetry was achieved by reducing loading on both limbs.

Return-to-sport quadriceps strength symmetry impacts 5-year cartilage integrity after anterior cruciate ligament reconstruction: A preliminary analysis.

Quadriceps femoris strength asymmetry at the time of return to sports participation after anterior cruciate ligament (ACL) reconstruction contributes to worse function and asymmetric landing patterns, but the impact on longitudinal outcomes is not known. This study determined if young athletes after ACL reconstruction with quadriceps femoris strength asymmetry at a return to sports clearance would demonstrate markers of knee cartilage degeneration 5 years later compared to those with symmetric quadriceps femoris strength at return to sports. Participants (n = 27) were enrolled at the time of medical clearance for sports participation (baseline testing) and followed for 5 years. At baseline, quadriceps femoris strength was measured bilaterally and a limb symmetry index was used to divide the cohort into two groups: return to sport clearance with high quadriceps femoris strength (RTS-HQ; limb symmetry index ≥ 90%) and return to sport clearance with low quadriceps femoris strength (RTS-LQ; limb symmetry index < 85%). At 5 years post-baseline, quantitative magnetic resonance imaging (T2 relaxation times (ms): involved knee medial/lateral femoral condyle and tibial plateau) data were collected. Group differences were evaluated with independent samples t tests. At 5 years post-return to sports, the RTS-LQ strength group (n = 14) demonstrated elevated T2 relaxation times at the anterior region of the lateral femoral condyle compared to the RTS-HQ strength group (n = 13). Clinical Significance: Just over 50% of this cohort was cleared for sports participation with involved limb quadriceps femoris strength deficits that may contribute to early markers of knee cartilage degeneration within the subsequent 5 years.

Effects of age and knee osteoarthritis on the modular control of walking: A pilot study.

BACKGROUND: Older adults and individuals with knee osteoarthritis (KOA) often exhibit reduced locomotor function and altered muscle activity. Identifying age- and KOA-related changes to the modular control of gait may provide insight into the neurological mechanisms underlying reduced walking performance in these populations. The purpose of this pilot study was to determine if the modular control of walking differs between younger and older adults without KOA and adults with end-stage KOA. METHODS: Kinematic, kinetic, and electromyography data were collected from ten younger (23.5 ± 3.1 years) and ten older (63.5 ± 3.4 years) adults without KOA and ten adults with KOA (64.0 ± 4.0 years) walking at their self-selected speed. Separate non-negative matrix factorizations of 500 bootstrapped samples determined the number of modules required to reconstruct each participant's electromyography. One-way Analysis of Variance tests assessed the effect of group on walking speed and the number of modules. Kendall rank correlations (τb) assessed the association between the number of modules and self-selected walking speed. RESULTS: The number of modules required in the younger adults (3.2 ± 0.4) was greater than in the individuals with KOA (2.3 ± 0.7; p = 0.002), though neither cohorts' required number of modules differed significantly from the unimpaired older adults (2.7 ± 0.5; p ≥ 0.113). A significant association between module number and walking speed was observed (τb = 0.350, p = 0.021) and individuals with KOA walked significantly slower (0.095 ± 0.21 m/s) than younger adults (1.24 ± 0.15 m/s; p = 0.005). Individuals with KOA also exhibited altered module activation patterns and composition (which muscles are associated with each module) compared to unimpaired adults. CONCLUSION: These findings suggest aging alone may not significantly alter modular control; however, the combined effects of knee osteoarthritis and aging may together impair the modular control of gait.

Young athletes after ACL reconstruction with asymmetric quadriceps strength at the time of return-to-sport clearance demonstrate drop-landing asymmetries two years later.

BACKGROUND: Quadriceps strength asymmetry at the time of return-to-sport (RTS) after anterior cruciate ligament reconstruction (ACLR) contributes to altered landing mechanics. However, the impact of RTS quadriceps strength on longitudinal alterations in landing mechanics, a risk factor for poor knee joint health over time, is not understood. The purpose of this study was to test the hypothesis that young athletes with quadriceps strength asymmetry at the time of RTS clearance after ACLR would demonstrate asymmetric landing mechanics 2 years later compared to those without quadriceps strength asymmetry. METHODS: We followed 57 young athletes (age at RTS = 17.6 ± 3.0 years; 77% females) with primary, unilateral ACLR for 2 years following RTS clearance. At RTS, we measured isometric quadriceps strength bilaterally and calculated limb-symmetry indices [LSI = (involved/uninvolved)×100%]. Using RTS quadriceps LSI, we divided participants into High-Quadriceps (HQ; LSI ≥ 90%) and Low-Quadriceps (LQ; LSI < 85%) groups. Two years later, we assessed landing mechanics during a drop-vertical jump (DVJ) task using three-dimensional motion analysis. We compared involved/uninvolved limb values and LSI between the HQ and LQ groups using Mann-Whitney U tests. RESULTS: The LQ group (n = 26) demonstrated greater asymmetry (lower LSI) during landing at 2 years post-RTS for knee flexion excursion (p = 0.016) and peak vertical ground reaction force (p = 0.006) compared to the HQ group (n = 28). There were no group differences in uninvolved or involved limb values for all variables (all p > 0.093). CONCLUSION: Young athletes after ACLR with quadriceps strength asymmetry at the time of RTS favored the uninvolved limb during DVJ landing 2 years later. These landing asymmetries may relate to long-term knee joint health after ACLR.

High kinesiophobia and pain catastrophizing in people with articular cartilage defects in the knee and associations with knee function.

PURPOSE: The purpose of this study was to evaluate the extent to which individuals with knee articular cartilage defects (ACDs) have kinesiophobia and pain catastrophizing, and how these psychological factors relate to self-reported knee outcomes. METHODS: Thirty-five individuals seeking surgical consultation for an ACD in the knee confirmed with 3.0T MRI and 18 controls without history of knee injury participated in the study. Kinesiophobia was measured with the Tampa Scale of Kinesiophobia (TSK), and scored using the modified 11-item (TSK-11) methods. Pain catastrophizing was measured with the Pain Catastrophizing Scale (PCS). Data were analyzed using descriptive statistics, independent t-tests, chi-squared tests and Spearman's correlation coefficients, as appropriate (α = 0.05). RESULTS: Participants with ACDs reported higher TSK-11 scores (median 27 [IQR 25-29]) and higher PCS scores (median 10 [IQR 4-18]) than controls (median TSK-11 16 [IQR 14-17], p < 0.001; median PCS 0 [IQR 0-9], p < 0.001). Within those with knee ACDs, higher TSK-11 scores were associated with worse knee pain, function on activities of daily living, sports/recreation, and knee-related quality of life scores (rho = -0.38 to -0.61). Higher pain catastrophizing was associated with worse function with activities of daily living and knee-related quality of life (rho = -0.37 to -0.40). CONCLUSIONS: Kinesiophobia and pain catastrophizing in people with knee ACDs were higher than controls. Higher kinesiophobia and pain catastrophizing were associated with worse function and quality of life. Further study of the impact of these psychological factors on outcomes and prognosis in people with knee ACDs is warranted.

Reduced 2-D Frontal Plane Motion During Single-Limb Landing Is Associated With Risk of Future Anterior Cruciate Ligament Graft Rupture After Anterior Cruciate Ligament Reconstruction and Return to Sport: A Pilot Study.

OBJECTIVES: To evaluate the association between 2-D frontal plane movement and second anterior cruciate ligament (ACL) injury risk in young athletes at return to sport (RTS) after ACL reconstruction. DESIGN: Prospective cohort. METHODS: Forty-nine participants who had ACL reconstruction (mean ± SD age, 16.5 ± 3.0 years) performed a single-leg drop landing from a 31-cm box at the time of their RTS. Frontal plane trunk, pelvis, and knee angles were measured using 2-D video analysis at the point of maximum depth during landing. Summated frontal plane angles were calculated by adding trunk, pelvis, and knee angles. Participants were grouped based on whether or not they sustained an ACL graft rupture over the 24 months after RTS. RESULTS: Seven participants (14%) sustained an ipsilateral graft rupture within 24 months after RTS. Participants who suffered a second ACL injury had a significant reduction in the summated frontal plane angle of the trunk, pelvis, and knee (P = .018) and of the trunk and knee (P = .02) compared to those who did not suffer a second injury. For every 5° increase in the summated trunk, pelvis, and knee angle (odds ratio [OR] = 0.54; 95% confidence interval [CI]: 0.31, 0.94) and the summated trunk and knee angle (OR = 0.48; 95% CI: 0.25, 0.94), the athletes were 46% to 52% less likely to sustain a graft rupture. CONCLUSION: Athletes who suffered an ACL graft rupture within 24 months of RTS had a more rigid posture when landing compared to their uninjured peers. The results of this pilot study should be replicated in a larger sample to determine whether this method has merit as a screening tool to identify athletes at high risk for second ACL injury. J Orthop Sports Phys Ther 2021;51(2):82-87. Epub 25 Dec 2020. doi:10.2519/jospt.2021.9302.

TIMELINE OF GAINS IN QUADRICEPS STRENGTH SYMMETRY AND PATIENT-REPORTED FUNCTION EARLY AFTER ACL RECONSTRUCTION.

BACKGROUND: Quadriceps weakness is a predictor of long-term knee function and strength recovery can vary from months to years after anterior cruciate ligament reconstruction (ACLR). However, few studies evaluate quadriceps strength and self-reported function within the first several weeks after ACLR. HYPOTHESIS/PURPOSE: To examine changes over time in quadriceps strength symmetry, quadriceps peak torque, and self-reported knee function prior to and at six, 12, and 24 weeks post-ACLR. The hypotheses were 1) quadriceps strength symmetry, bilateral quadriceps peak torque, and patient-reported function would improve over time from pre-ACLR to 24 weeks post-ACLR and 2) significant improvements in patient-reported function, but not strength symmetry, would occur between time points. STUDY DESIGN: Prospective, cohort study. METHODS: Thirty participants completed four testing sessions: pre-surgery and six, 12, and 24 weeks post-ACLR. Isometric quadriceps strength testing was performed at six weeks and isokinetic quadriceps strength was measured at all other testing points. Quadriceps index was calculated to evaluate between limb quadriceps strength symmetry. The Knee injury and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC) were administered at each time point. A repeated-measures analysis of variance evaluated changes over time, with post-hoc comparisons to determine at which time-point significant changes occurred. RESULTS: Quadriceps strength symmetry, involved limb quadriceps peak torque and all patient-reported outcome scores increased over time (p<0.02). Post-hoc tests showed that neither self-reported outcomes, nor quadriceps index improved between pre-surgery and six-weeks post-ACLR. From six to 12 weeks post-ACLR, scores on IKDC and KOOS Pain, Symptoms, Quality of Life, and Sport subscales improved (p≤0.003). From 12 to 24 weeks post-ACLR, quadriceps strength symmetry, involved limb quadriceps peak torque, KOOS-Symptoms, Quality of Life, and Sport subscales and the IKDC improved (p≤0.01). Uninvolved limb quadriceps peak torque did not change across any time point (p≥0.18). CONCLUSION: Patient-reported knee function increased between six and 24 weeks post-ACLR, while increases in involved limb quadriceps strength and quadriceps strength symmetry were not noted until 12-24 weeks post-ACLR. LEVEL OF EVIDENCE: 2b, individual cohort study.

Treatment After Anterior Cruciate Ligament Injury: Panther Symposium ACL Treatment Consensus Group.

Treatment strategies for anterior cruciate ligament (ACL) injuries continue to evolve. Evidence supporting best-practice guidelines for the management of ACL injury is to a large extent based on studies with low-level evidence. An international consensus group of experts was convened to collaboratively advance toward consensus opinions regarding the best available evidence on operative versus nonoperative treatment for ACL injury. The purpose of this study was to report the consensus statements on operative versus nonoperative treatment of ACL injuries developed at the ACL Consensus Meeting Panther Symposium 2019. There were 66 international experts on the management of ACL injuries, representing 18 countries, who were convened and participated in a process based on the Delphi method of achieving consensus. Proposed consensus statements were drafted by the scientific organizing committee and session chairs for the 3 working groups. Panel participants reviewed preliminary statements before the meeting and provided initial agreement and comments on the statement via online survey. During the meeting, discussion and debate occurred for each statement, after which a final vote was then held. Ultimately, 80% agreement was defined a priori as consensus. A total of 11 of 13 statements on operative versus nonoperative treatment of ACL injury reached consensus during the symposium. Overall, 9 statements achieved unanimous support, 2 reached strong consensus, 1 did not achieve consensus, and 1 was removed because of redundancy in the information provided. In highly active patients engaged in jumping, cutting, and pivoting sports, early anatomic ACL reconstruction is recommended because of the high risk of secondary meniscal and cartilage injuries with delayed surgery, although a period of progressive rehabilitation to resolve impairments and improve neuromuscular function is recommended. For patients who seek to return to straight-plane activities, nonoperative treatment with structured, progressive rehabilitation is an acceptable treatment option. However, with persistent functional instability, or when episodes of giving way occur, anatomic ACL reconstruction is indicated. The consensus statements derived from international leaders in the field will assist clinicians in deciding between operative and nonoperative treatment with patients after an ACL injury.