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Physical activity (PA) promotes better cardiometabolic health, physical function, brain health and longevity. In contrast, prolonged sedentary behaviour (SB) is a risk factor for many chronic diseases and poor health. Limited research has evaluated or synthesised how competitive sports participation influences PA across the lifespan. Some evidence suggests, ironically, that former competitive athletes may be insufficiently active and current athletes may be highly sedentary away from sport. This study describes the protocol for a systematic review and meta-analysis on activity levels across the intensity spectrum in athletes, addressing the primary research question: is sports participation significantly associated with PA and/or SB among current and former competitive athletes? PubMed, Embase, Cochrane Database of Systematic Reviews, Web of Science and SPORTDiscus databases will be searched. Two reviewers will independently screen titles/abstracts and full texts of selected abstracts. Data will be extracted regarding the study population, sport played, PA measures and protocols, outcomes of interest and findings. Primary outcomes will include step counts, daily activity across the intensity spectrum (ie, sedentary, light, moderate and vigorous PA), metabolic equivalent of task and whole-day energy expenditure. Secondary outcomes will include additional accelerometry measures of PA, activity patterns and self-reported PA. The risk of bias will be assessed using the National Institutes of Health Study Quality Assessment Tools. Extracted data will be presented using narrative synthesis and tabular presentation. Meta-analyses will be conducted to determine outcomes with sufficient data. PROSPERO registration number: CRD42024469267.https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=469267., Competing Interests: None declared., (Copyright © Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The purpose was to explore quadriceps electromechanical function (quadriceps latency) during gait after anterior cruciate ligament injury as a predictor for radiographic knee osteoarthritis 6-years after anterior cruciate ligament reconstruction. Change in latency after preoperative physical therapy was also examined., Methods: Quadriceps latency (time between peak knee moment and quadriceps electromyography) was calculated before preoperative physical therapy (2.4 [0.5-7.5] months after anterior cruciate ligament injury) and after preoperative physical therapy in 24 athletes. Participants were dichotomized into osteoarthritis (Kellgren and Lawrence grade ≥ 2) and non-osteoarthritis groups at 6-years. Forward selection logistic regression was performed using z-score normalized quadriceps latency and demographics. A 2 × 2 repeated measure ANOVA was performed for quadriceps latency between groups before and after preoperative physical therapy., Findings: Quadriceps latency before preoperative physical therapy was the only predictor of 6-year radiographic osteoarthritis (p = 0.014, odds ratio [95% confidence interval] = 5.859 [1.435-23.924]). Time by group interaction was observed for quadriceps latency (p = 0.039, η 2 p = 0.179). In the osteoarthritis group, latency may reduce after training (before preoperative physical therapy = 115.7 ± 20.6 ms, after preoperative physical therapy = 99.5 ± 24.0 ms, p = 0.082)., Interpretation: Prolonged latency after anterior cruciate ligament injury may predict post-traumatic knee osteoarthritis 6-years after anterior cruciate ligament reconstruction. Latency may shorten with preoperative physical therapy, yet athletes still moved on to develop osteoarthritis. Quadriceps function may need intervention immediately following anterior cruciate ligament injury for prevention of post-traumatic knee osteoarthritis., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Lynn Snyder-Mackler reports financial support was provided by National Institutes of Health. Thomas Buchanan reports financial support was provided by National Institute of Health. Jacob Capin reports financial support was provided by National Institutes of Health. Elizabeth Wellsandt reports financial support was provided by National Institutes of Health. Elanna Arhos reports financial support was provided by National Institutes of Health. Elanna Arhos reports financial support was provided by Foundation for Physical Therapy. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Sports participation confers many health benefits yet greatly increases injury risk. Long-term health outcomes in former athletes and transition to life after competitive sports are understudied. Ending a sport may pose physical and psychosocial challenges. The purpose was to determine the lived experiences of former competitive athletes and how their sports participation impacted their long-term health and well-being. Former college varsity athletes participated in semistructured interviews focusing on their experiences, including past and current health, the impact of injuries, activity, exercise, diet and transition to life after competitive sport. Thematic analysis was completed using a collaborative, iterative process. Thirty-one (16 female, 15 male) former college athletes aged 51.3±7.4 years were interviewed. Six themes emerged: (1) lifelong athlete identity; (2) structure, support and challenges of the college athlete experience; (3) a big transition to life beyond competitive sport; (4) impact of competitive sport on long-term health; (5) facilitators and barriers to long-term health after sport and (6) transferable life skills. Continuing sports eased the transition for many but often delayed their postathlete void. Challenges included managing pain and prior injury (eg, If I didn't have my knee injury, I would definitely be more active ), reducing energy needs and intake (eg, When I was an athlete, I could eat anything; and unfortunately, that's carried into my regular life), lack of accountability, changed identity and lost resources and social support. Participants suggested a programme, toolkit, mentoring or exit course to facilitate the transition. While former athletes benefit from transferrable life skills and often continue sports and exercise, they face unique challenges such as managing pain and prior injury, staying active, reducing energy intake and changing identity. Future research should develop and evaluate a toolkit, programme and other resources to facilitate life after ending competitive sports under 'normal' conditions (eg, retirement) and after a career-ending injury., Competing Interests: Competing interests: The authors have nothing to disclose except for grant funding as acknowledged above., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Approximately 1 in 4 athletes returning to sports will sustain a second anterior cruciate ligament (ACL) injury. Psychological factors related to kinesiophobia, confidence, and psychological readiness are associated with second ACL injury; however, the evidence is conflicting., Hypothesis: Athletes who sustain a second ACL injury (ie, graft rupture or contralateral ACL rupture) within 2 years of ACL reconstruction (ACLR) would have greater kinesiophobia, less confidence, and lower psychological readiness prior to return to sport (RTS) compared with athletes who do not sustain a second ACL injury., Study Design: Secondary analysis of a prospective randomized trial., Level of Evidence: Level 3., Methods: A total of 39 female Level I/II athletes completed the following measures after postoperative rehabilitation and a 10-session RTS and second ACL injury prevention program: ACL Return to Sport after Injury (ACL-RSI) scale, the 11-item Tampa Scale of Kinesiophobia (TSK-11), and question 3 on the Knee injury and Osteoarthritis Outcome Score (KOOS) quality of life (QoL) subscale. Athletes were dichotomized based on whether they sustained a second ACL injury within 2 years of ACLR or not. Independent t tests determined group differences in TSK-11, KOOS-QoL, ACL-RSI, and the 3 individual components of the ACL-RSI (ie, emotions, confidence, risk appraisal)., Results: Nine athletes sustained a second ACL injury (4 graft ruptures and 5 contralateral ACL ruptures). The group that sustained a second ACL injury had higher scores on the ACL-RSI ( P = 0.03), higher on the risk appraisal questions of the ACL-RSI ( P < 0.01), and met RTS criteria sooner than athletes who did not ( P = 0.04). All second ACL injuries occurred in athletes who underwent primary ACLR with hamstring tendon autografts., Conclusion: Athletes who sustained a second ACL within 2 years of ACLR had a more positive psychological outlook, higher scores on the specific questions related to the risk appraisal construct of the ACL-RSI, and met RTS criteria sooner than athletes who did not sustain a second ACL injury., Clinical Relevance: Counseling athletes about delaying RTS to reduce the risk of second ACL injury may be especially important in athletes who display high psychological readiness and meet RTS criteria sooner., Competing Interests: The following authors declared potential conflicts of interest: R.Z. received a grant from the National Institutes of Health (NIH) for his PhD and received salary support via grant NCT04504344. E.A. received a grant from the NIH for salary support, and a grant from the Foundation for Physical Therapy Research PODS Level II Scholarship in support of her doctoral thesis. J.J.C. received a grant from the NIH, a grant from ACL-SPORTS randomized controlled trial, a Career Development Award from the Academy of Orthopaedic Physical Therapy, a grant from Veterans Health Administration Eastern Colorado Geriatric Research, Education, and a grant from the Clinical Center Advanced Geriatrics Fellowship. L.S.-M. consulted on an NIH research grant from the University of Kentucky, an NIH research grant from the University of Michigan, and the Brigham & Women’s Orthopedics Sports’ new research and performance center, and is also on the National Football League Scientific Advisory.

While sports medicine has traditionally focused on recovering from injury and returning athletes to sport safely after injury, there is a growing interest in the long-term health of athletes. The purpose of this scoping review was to (1) summarise the literature (methodologies and findings) on physical function, body composition and cardiometabolic health in midlife (age 40-65 years) former competitive athletes compared with non-athlete controls, (2) identify areas for future study in long-term health in athletes and (3) determine outcomes that could be evaluated in a future systematic review(s). We searched PubMed, CINAHL, Web of Science and SPORTDiscus for studies published between 2000 and 2022 evaluating former athletes and controls on physical function, body composition and/or cardiometabolic measures using MeSH terms. We identified 20 articles that met our criteria. Outcomes varied considerably across studies, most of which were cross-sectional and evaluated only males. Limited data suggest that former endurance athletes have leaner body compositions, higher aerobic capacity and better cardiometabolic indicators than controls; former athletes who maintain higher physical activity (ie, self-reported exercise) are healthier than those who do not; and former team sport athletes, who have higher injury prevalence, may have poorer functional performance than controls who were recreationally active in college. Studies rarely evaluated functional performance, did not control for prior injury or diet and seldom assessed current physical activity levels. Future research should include females and evaluate sex differences, control for prior sports-related injury(ies), quantify physical activity, use standardised outcome measures including performance-based functional assessments and incorporate longitudinal designs., Competing Interests: Competing interests: Funding for this work was provided by an NIH Director’s Early Independence Award to JJC (DP5-OD031833)., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Knowledge on physical activity recovery after COVID-19 survival is limited. The AFTER (App-Facilitated Tele-Rehabilitation) program for COVID-19 survivors randomized participants, following hospital discharge, to either education and unstructured physical activity or a telerehabilitation program. Step count data were collected as a secondary outcome, and we found no significant differences in total step count trajectories between groups at 6 weeks. Further step count data were not analyzed., Objective: The purpose of this analysis was to examine step count trajectories and correlates among all participants (combined into a single group) across the 12-week study period., Methods: Linear mixed models with random effects were used to model daily steps over the number of study days. Models with 0, 1, and 2 inflection points were considered, and the final model was selected based on the highest log-likelihood value., Results: Participants included 44 adults (41 with available Fitbit [Fitbit LLC] data). Initially, step counts increased by an average of 930 (95% CI 547-1312; P<.001) steps per week, culminating in an average daily step count of 7658 (95% CI 6257-9059; P<.001) at the end of week 3. During the remaining 9 weeks of the study, weekly step counts increased by an average of 67 (95% CI -30 to 163; P<.001) steps per week, resulting in a final estimate of 8258 (95% CI 6933-9584; P<.001) steps., Conclusions: Participants showed a marked improvement in daily step counts during the first 3 weeks of the study, followed by more gradual improvement in the remaining 9 weeks. Physical activity data and step count recovery trajectories may be considered surrogates for physiological recovery, although further research is needed to examine this relationship., Trial Registration: ClinicalTrials.gov NCT04663945; https://tinyurl.com/2p969ced., (©Laura Churchill, Mary Morrow, Jacob J Capin, Sarah E Jolley, Kristine Hare, Samantha MaWhinney, Jennifer E Stevens-Lapsley, Kristine M Erlandson. Originally published in JMIR Rehabilitation and Assistive Technology (https://rehab.jmir.org), 20.03.2023.)

OBJECTIVE: To describe the variation in outcomes and number of visits before and after implementing a care guideline for total knee arthroplasty (TKA) rehabilitation. DESIGN: Nonrandomized intervention study. METHODS: We compared 2558 patients with TKA who received care that was not standardized (non-care guideline [NCG] group) to 9797 patients with TKA who received care according to the care guideline (CG). We fit 2 Bayesian hierarchical linear regression models using the Knee Outcome Survey - Activities of Daily Living (KOS-ADL) change score and number of physical therapy (PT) visits as the response variables, controlling for relevant predictor variables. We also compared the ratio of the standard deviations of the KOS-ADL change scores and the number of PT visits within and between clinics. RESULTS: The overall estimated mean improvement in KOS-ADL change score was 23.0 points (95% confidence interval [CI]: 20.3, 25.7) in the NCG group and 28.7 points (95% CI: 27.5, 29.7) in the CG group; the mean difference was 5.6 (2.7-8.6). Mean KOS-ADL change scores were higher in the CG group than the NCG group in every clinic, although only 8 clinics improved significantly. The number of PT visits did not change meaningfully (NCG: mean, 10.7 [95% CI: 9.9, 11.5]; CG: mean, 10.5 [95% CI: 9.9, 10.9]). Variation in KOS-ADL change score decreased by 4% within clinics (CG-NCG ratio: 0.96 [95% CI: 0.93, 0.99]) and 63% between clinics (CG-NCG ratio: 0.37 [95% CI: 0.21, 0.62]). Variation in number of visits decreased by 7% within clinics (CG-NCG ratio: 0.93 [95% CI: 0.90, 0.96]) and 19% between clinics (CG-NCG ratio: 0.81 [95% CI: 0.39, 1.49]). CONCLUSION: Implementing a care guideline for TKA rehabilitation may improve outcomes and reduce unwarranted variation in practice within clinics and especially between clinics within a large health care system. J Orthop Sports Phys Ther 2023;53(3):151-158. Epub: 12 December 2022. doi:10.2519/jospt.2022.11370 .

OBJECTIVE: To describe the application and examine the influence of a continuous quality improvement intervention, which had a goal of standardizing care to reduce the proportion of patients who do not have a meaningful improvement in patient-reported outcomes following total knee arthroplasty (TKA). DESIGN: Continuous quality improvement. METHODS: A physical therapy (PT) care guideline was initiated in 2013 for patients following TKA. The Knee Outcome Survey - Activities of Daily Living (KOS-ADL) was measured at every visit, and scores were extracted from a clinical outcomes database to calculate the proportion of patients who did not achieve a minimal clinically important difference. Based on logistic regression analysis, we compared the proportion of patients who did not progress on the KOS-ADL in a non-care guideline group (2008-2012) to a care guideline (CG) group (2014-2019). RESULTS: This study included 12 355 patients (aged 18-92 years) following TKA incurring at least 3 PT visits from 2008 to 2019. The percentage of patients who did not progress in the non-care guideline group was 25.8% and in the care guideline group 14.3% (P<0.001). The relationship between care guideline adherence and lack of progression on the KOS-ADL was statistically significant, X 2 ( df = 1) = 148.7, P<.001. CONCLUSION: The percentage of patients who did not achieve meaningful progress on the KOS-ADL declined significantly in the 6 years after implementing a TKA care guideline without an increase in the number of clinical visits. The standardized care guideline was associated with meaningful improvements for patients following TKA when applied in conjunction with PT access to outcome data, feedback through audits, performance goals, and financial incentives. J Orthop Sports Phys Ther 2023;53(3):143-150. Epub: 12 December 2022. doi:10.2519/jospt.2022.11369 .

Objective: Evaluate patellofemoral cartilage health, as assessed by quantitative magnetic resonance imaging (qMRI) T 2 relaxation times, 24-months after ACL reconstruction (ACLR) and determine if they were associated with patellofemoral contact forces and knee mechanics during gait 3 months after surgery., Design: Thirty individuals completed motion analysis during overground walking at a self-selected speed 3 months after ACLR. An EMG-driven neuromusculoskeletal model was used to determine muscle forces, which were then used in a previously described model to estimate patellofemoral contact forces. Biomechanical variables of interest included peak patellofemoral contact force, peak knee flexion angle and moment, and walking speed. These same participants underwent a sagittal bilateral T 2 mapping qMRI scan 24-months after surgery. T 2 relaxation times were estimated for both patellar and trochlear cartilage. Paired t-tests were used to compare T 2 relaxation times between limbs while Pearson correlations and linear regressions were utilized to assess the association between the biomechanical variables of interest and T 2 relaxation times., Results: Prolonged involved limb trochlear T 2 relaxation times (vs uninvolved) were present 24-months after surgery, indicating worse cartilage health. No differences were detected in patellar cartilage. Significant negative associations were present within the involved limb for all the biomechanical variables of interest 3 months after ACLR and trochlear T 2 relaxation times at 24-months. No associations were found in patellar cartilage or within the uninvolved limb., Conclusions: Altered involved limb trochlear cartilage health is present 24-months after ACLR and may be related to patellofemoral loading and other walking gait mechanics 3 months after surgery., (Copyright © 2022 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Purpose: Bone-patellar tendon-bone (BPTB) graft harvest for anterior cruciate ligament reconstruction alters patellar tendon properties, which inflict poor quadriceps neuromuscular function. BPTB autografts are associated with higher rates of posttraumatic osteoarthritis, which in turn is associated with pathological gait. The purpose of this study was to investigate the latency between the time of peak quadriceps activity and the peak knee flexion moment during gait, between those with BPTB grafts ( n = 23) and other graft types (hamstring autograft or allografts, n = 54), 5 ± 2 months and 2 yr (25 ± 3 months) after anterior cruciate ligament reconstruction. We hypothesized that longer latencies would be observed in the BPTB graft group in the involved limb. We expected latencies to shorten over time., Methods: Knee moments and quadriceps EMG were collected during gait, and vastus medialis, vastus lateralis, rectus femoris (RF), and quadriceps latencies were calculated. Linear mixed-effects models were used to compare latencies between graft types and over the two time points., Results: The main effects of graft type were observed for vastus medialis ( P = 0.005) and quadriceps ( P = 0.033) latencies with the BPTB graft group demonstrating longer latencies. No main effects of graft type were observed for vastus lateralis ( P = 0.051) and RF ( P = 0.080) latencies. Main effects of time were observed for RF latency ( P = 0.022)., Conclusions: Our hypothesis that the BPTB graft group would demonstrate longer extensor latency was supported. Contrary to our second hypothesis, however, latency only improved in RF and regardless of graft type, indicating that neuromuscular deficits associated with BPTB grafts may persist 2 yr after surgery. Persistent deficits may be mediated by changes in the patellar tendon's mechanical properties. Graft-specific rehabilitation may be warranted to address the long-term neuromechanical deficits that are present after BPTB graft harvest., (Copyright © 2022 by the American College of Sports Medicine.)

Gait alterations after anterior cruciate ligament reconstruction (ACLR) are commonly reported and have been linked to posttraumatic osteoarthritis development. While knee gait alterations have been studied at several time points after ACLR, little is known about how these biomechanical variables change earlier than 6 months after surgery, nor is much known about how they differ over the entire stance phase of gait. The purpose of this study was to examine knee gait biomechanical variables over their entire movement pattern through stance at both 3 and 6 months after ACLR and to study the progression of interlimb asymmetry between the two postoperative time points. Thirty-five individuals underwent motion analysis during overground walking 3 (3.2 ± 0.5) and 6 (6.4 ± 0.7) months after ACLR. Knee biomechanical variables were compared between limbs and across time points through 100% of stance using statistical parametric mapping; this included a 2 × 2 (Limb × Time) repeated measures analysis of variance and two-tailed t-tests. Smaller knee joint angles, moments, extensor forces, and medial compartment forces were present in the involved versus uninvolved limb. Interlimb asymmetries were present at both time points but were less prevalent at 6 months. The uninvolved limb's biomechanical variables stayed relatively consistent over time, while the involved limb's trended toward that of the uninvolved limb. Statement of Clinical Significance: Interventions to correct asymmetrical gait patterns after ACLR may need to occur early after surgery and may need to focus on multiple parts of stance phase., (© 2022 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Objectives: Determine the safety, feasibility and initial efficacy of a multicomponent telerehabilitation programme for COVID-19 survivors., Design: Pilot randomised feasibility study., Setting: In-home telerehabilitation., Participants: 44 participants (21 female, mean age 52 years) discharged home following hospitalisation with COVID-19 (with and without intensive care unit (ICU) stay)., Interventions: Participants were block randomised 2:1 to receive 12 individual biobehaviourally informed, app-facilitated, multicomponent telerehabilitation sessions with a licenced physical therapist (n=29) or to a control group (n=15) consisting of education on exercise and COVID-19 recovery trajectory, physical activity and vitals monitoring, and weekly check-ins with study staff. Interventions were 100% remote and occurred over 12 weeks., Primary and Secondary Outcome Measures: The primary outcome was feasibility, including safety and session adherence. Secondary outcomes included preliminary efficacy outcomes including tests of function and balance; patient-reported outcome measures; a cognitive assessment; and average daily step count. The 30 s chair stand test was the main secondary (efficacy) outcome., Results: No adverse events (AEs) occurred during testing or in telerehabilitation sessions; 38% (11/29) of the intervention group compared with 60% (9/15) of the control group experienced an AE (p=0.21), most of which were minor, over the course of the 12-week study. 27 of 29 participants (93%; 95% CI 77% to 99%) receiving the intervention attended ≥75% of sessions. Both groups demonstrated clinically meaningful improvement in secondary outcomes with no statistically significant differences between groups., Conclusion: Fully remote telerehabilitation was safe, feasible, had high adherence for COVID-19 recovery, and may apply to other medically complex patients including those with barriers to access care. This pilot study was designed to evaluate feasibility; further efficacy evaluation is needed., Trial Registration Number: NCT04663945., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Range of motion (ROM) and pain often define successful recovery after total knee arthroplasty (TKA), but these routine clinical outcomes correlate poorly or not at all to functional capacity after TKA. The purpose of this Perspective is to underscore the importance of muscle strength and performance-based functional tests in addition to knee ROM and patient-reported outcome (PRO) measures to evaluate outcomes after TKA. Specifically: (1) muscle strength is the rate-limiting step for recovery of function after TKA; (2) progressive rehabilitation targeting early quadriceps muscle strengthening improves outcomes and does not compromise ROM after TKA; (3) ROM and PROs fail to fully capture functional limitations after TKA; and (4) performance-based functional tests are critical to evaluate function objectively after TKA. This Perspective also addresses studies that question the need for or benefit of physical therapy after TKA because their conclusions focus only on ROM and PRO measures. Future research is needed to determine the optimal timing, delivery, intensity, and content of physical therapy., (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Physical Therapy Association. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Purpose: Asymmetrical gait mechanics after anterior cruciate ligament reconstruction (ACLR) are associated with the development of posttraumatic knee osteoarthritis. Current measures of gait mechanics have focused heavily on peak magnitudes of knee kinematics, kinetics, and joint contact forces but have seldom considered the rate of knee loading, cumulative knee load, or the timing of motor input surrounding peaks. The purpose of this study was to introduce and describe novel metrics of gait using temporal characteristics of kinetics and EMG to identify neuromuscular deficits of the quadriceps in patients after ACLR., Methods: Gait mechanics were assessed 6 months (n = 145) and 24 months (n = 116) after ACLR. External knee flexion rate of moment development (RMD) and knee flexion moment impulse (KFMI) leading up to the time of peak knee flexion moment (pKFM), peak RMD between initial contact to pKFM, and cumulative KFMI were calculated. Extensor latencies from the quadriceps, vastus medialis, vastus lateralis, and rectus femoris (time of pKFM - time of peak EMG activity) during the weight acceptance phase of gait were also calculated. Paired-sample t-tests (α = 0.05) were performed between limbs at both time points., Results: Slower RMD, smaller KFMI, and longer extensor latencies in the involved compared with uninvolved limb were observed across all measures at 6 months (P < 0.005). At 24 months, RMDpeak was slower, and KFMI50ms, KFMI100ms, and KFMItotal were lower in the involved limb (P < 0.003), but no other asymmetries were found., Conclusions: Slower RMD, smaller KFMI, and prolonged extensor latencies may characterize neuromuscular deficits underlying aberrant gait mechanics early after ACLR. RMD, KFMI, and extensor latencies during gait should be considered in the future to quantify asymmetrical movement patterns observed after ACLR and as markers of recovery., (Copyright © 2022 by the American College of Sports Medicine.)

Background: COVID-19 is a global pandemic with poorly understood long-term consequences. Determining the trajectory of recovery following COVID-19 hospitalization is critical for prioritizing care, allocating resources, facilitating prognosis, and informing rehabilitation. The purpose of this study was to prospectively evaluate recovery following COVID-19 hospitalization., Methods: Participants age 18 years or older who were hospitalized for ≥24 h due to COVID-19 completed phone/video call virtual assessments (including the 10-time chair rise test) and survey forms at three time points (2-6, 12, and 18 weeks) after hospital discharge. Univariate logistic and linear regression models assessed the associations of the outcomes with primary predictors (categorical age, sex, race/ethnicity group, and categorical pre-hospitalization frailty) at baseline; the same were used to assess differences in change from week 2-6 (continuous outcomes) or outcome persistence/worsening (categorical) at last contact., Results: One hundred nine adults (age 53.0 [standard deviation 13.1]; 53% female) participated including 43 (39%) age 60 or greater; 59% identified as an ethnic and/or racial minority. Over 18 weeks, the mean time to complete the 10-time chair rise test decreased (i.e., improved) by 6.0 s (95% CI: 4.1, 7.9 s; p < 0.001); this change did not differ by pre-hospital frailty, race/ethnicity group, or sex, but those age ≥ 60 had greater improvement. At weeks 2-6, 67% of participants reported a worse Clinical Frailty Scale category compared to their pre-hospitalization level, whereas 42% reported a worse frailty score at 18 weeks. Participants who did not return to pre-hospitalization levels were more likely to be female, younger, and report a pre-hospitalization category of 'very fit' or 'well'., Conclusions: We found that functional performance improved from weeks 2-6 to 18 weeks of follow-up; that incident clinical frailty developed in some individuals following COVID-19; and that age, sex, race/ethnicity, and pre-hospitalization frailty status may impact recovery from COVID-19. Notably, individuals age 60 and older were more likely than those under age 45 years to return to their pre-hospitalization status and to make greater improvements in functional performance. The results of the present study provide insight into the trajectory of recovery among a representative cohort of individuals hospitalized due to COVID-19., (© 2022. The Author(s).)

Osteoarthritis development after ACL reconstruction (ACLR) is not well understood. Investigators have examined associations between knee biomechanical alterations and quantitative MRI (qMRI) variables, reflective of cartilage health, 12-60 months following ACLR; however, none have done so early after surgery. As part of an exploratory study, 45 individuals (age, 23 ± 7 years) underwent motion analysis during walking and qMRI 3 months after ACLR. For each limb, peak knee adduction moment (pKAM) and peak knee flexion moment (pKFM) were determined using inverse dynamics and peak medial compartment force was calculated using a neuromusculoskeletal model. T 2 relaxation times in the medial compartment and linear regressions were used to determine the associations between gait variables and deep and superficial cartilage T 2 relaxation times in six regions. pKAM was positively associated with deep layer T 2 relaxation times within the femoral central and posterior regions when examined in the involved limb and from an interlimb difference perspective (involved limb - uninvolved limb). After adjusting for age, the association between interlimb difference of pKAM and interlimb difference of deep layer T 2 relaxation times in the tibial central region became significant (p = .043). Interlimb difference of pKFM was negatively associated with interlimb difference of deep layer T 2 relaxation times within the femoral central and posterior regions. These associations suggest that degenerative pathways leading to osteoarthritis may be detectable as early as 3 months after reconstruction. Preventative therapeutic techniques may need to be employed early in the rehabilitation process to prevent cartilage degradation., (© 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Although most patients are satisfied with outcomes after total knee arthroplasty (TKA), many retain preoperative altered gait mechanics. Identifying patient characteristics associated with gait mechanics will improve rehabilitation strategies and enhance our understanding of movement disorders. Therefore, the purpose of this study was to identify which patient characteristics are related to gait mechanics in the surgical limb during walking post-TKA. Patient characteristics included age, body mass, sex, quadriceps strength, self-reported function, and knee pain. General linear regression was used to compare patient characteristics associated with gait mechanics, after controlling for gait speed, functional capacity and time from surgery. We tested 191 patients cross-sectionally at 6-24 months after primary, unilateral TKA. Quadriceps weakness in the surgical limb was associated with less peak vertical ground reaction force (PvGRF) (β = .245, p = .044), knee extension moment (β = .283, p = .049), and knee extension excursion (β = .298, p = .038). Older age (β = .168, p = .050) was associated with less PvGRF. Quadriceps strength in the nonsurgical limb (β = -.357, p = .021) was associated with greater knee extension excursion in the surgical limb. Females with TKA (β = -.276, p = .007) had less knee flexion excursion compared to males. Faster gait speed was also associated with greater PvGRF (β = .585, p < .001), knee extensor moment (β = .481, p < .001), and knee flexion excursion (β = .318, p < .001). Statement of Clinical Significance: This study showed quadriceps weakness, slower gait speed, older age and being female were related to altered gait mechanics post-TKA. These findings will help clinicians better educate patients and develop targeted interventions for improving care in patients post-TKA., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Early-onset knee osteoarthritis (OA) is associated with gait asymmetries after anterior cruciate ligament reconstruction (ACLR). Women have higher risks of sustaining non-contact injuries, and are more likely to present with aberrant movement patterns associated with the mechanism of injury (MOI). We hypothesized that sex and MOI would influence gait after ACLR. Seventy participants, grouped by sex and MOI, completed biomechanical testing during over-ground walking when they had full knee range of motion, trace or less knee effusion, greater than 80% quadriceps strength limb symmetry index, ability to hop on each leg without pain, and initiated running. Bilateral knee kinetics, kinematics, and joint contact forces were compared using mixed-model analysis of variance (α = .05). There was a three-way interaction effect of sex × MOI × limb for peak medial compartment contact force (P = .002), our primary outcome measure previously associated with OA development. Men with non-contact injuries walked with asymmetry characterized by underloading of the involved limb. Men with contact injuries walked with the most symmetrical loading. In women, no clear pattern emerged based on MOI. Targeting, and possibly prioritizing interventions for athletes who present with gait asymmetries after ACLR based on sex and MOI, may be necessary to optimize outcomes. Statement of Clinical Significance: Sex and MOI may influence walking mechanics, and could be considered in future interventions to target gait symmetry, as a response to interventions may vary based on differences in sex and MOI., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Background: Gait asymmetries after anterior cruciate ligament reconstruction (ACLR) may lead to radiographic knee osteoarthritis. Slower walking speeds have been associated with biomarkers suggesting cartilage breakdown. The relationship between walking speed and gait symmetry after ACLR is unknown., Hypothesis/purpose: To determine the relationship between self-selected walking speeds and gait symmetry in athletes after primary, unilateral ACLR., Study Design: Secondary analysis of a clinical trial., Methods: Athletes 24±8 weeks after primary ACLR walked at self-selected speeds as kinematics, kinetics, and electromyography data were collected. An EMG-driven musculoskeletal model was used to calculate peak medial compartment contact force (pMCCF). Variables of interest were peak knee flexion moment (pKFM) and angle (pKFA), knee flexion and extension (KEE) excursions, peak knee adduction moment (pKAM), and pMCCF. Univariate correlations were run for walking speed and each variable in the ACLR knee, contralateral knee, and interlimb difference (ILD)., Results: Weak to moderate positive correlations were observed for walking speed and all variables of interest in the contralateral knee (Pearson's r=.301-.505, p≤0.01). In the ACLR knee, weak positive correlations were observed for only pKFM (r=.280, p=0.02) and pKFA (r=.263, p=0.03). Weak negative correlations were found for ILDs in pKFM (r=-0.248, p=0.04), KEE (r=-.260, p=0.03), pKAM (r=-.323, p<0.01), and pMCCF (r=-.286, p=0.02)., Conclusion: Those who walk faster after ACLR have more asymmetries, which are associated with the development of early OA. This data suggests that interventions that solely increase walking speed may accentuate gait symmetry in athletes early after ACLR. Gait-specific, unilateral, neuromuscular interventions for the ACLR knee may be needed to target gait asymmetries after ACLR., Level of Evidence: III.

Background: After anterior cruciate ligament (ACL) reconstruction (ACLR), biomechanical asymmetries during gait are highly prevalent, persistent, and linked to posttraumatic knee osteoarthritis. Quadriceps strength is an important clinical measure associated with preoperative gait asymmetries and postoperative function and is a primary criterion for return-to-sport clearance. Evidence relating symmetry in quadriceps strength with gait biomechanics is limited to preoperative and early rehabilitation time points before return-to-sport training., Purpose/hypothesis: The purpose was to determine the relationship between symmetry in isometric quadriceps strength and gait biomechanics after return-to-sport training in athletes after ACLR. We hypothesized that as quadriceps strength symmetry increases, athletes will demonstrate more symmetric knee joint biomechanics, including tibiofemoral joint loading during gait., Study Design: Cross-sectional study; Level of evidence, 3., Methods: Of 79 athletes enrolled in the ACL-SPORTS Trial, 76 were participants in this study after completing postoperative rehabilitation and 10 return-to-sport training sessions (mean ± SD, 7.1 ± 2.0 months after ACLR). All participants completed biomechanical walking gait analysis and isometric quadriceps strength assessment using an electromechanical dynamometer. Quadriceps strength was calculated using a limb symmetry index (involved limb value / uninvolved limb value × 100). The biomechanical variables of interest included peak knee flexion angle, peak knee internal extension moment, sagittal plane knee excursion at weight acceptance and midstance, quadriceps muscle force at peak knee flexion angle, and peak medial compartment contact force. Spearman rank correlation (ρ) coefficients were used to determine the relationship between limb symmetry indexes in quadriceps strength and each biomechanical variable; alpha was set to .05., Results: Of the 76 participants, 27 (35%) demonstrated asymmetries in quadriceps strength, defined by quadriceps strength symmetry <90% (n = 23) or >110% (n = 4) (range, 56.9%-131.7%). For the biomechanical variables of interest, 67% demonstrated asymmetry in peak knee flexion angle; 68% and 83% in knee excursion during weight acceptance and midstance, respectively; 74% in internal peak knee extension moment; 57% in medial compartment contact force; and 74% in quadriceps muscle force. There were no significant correlations between quadriceps strength index and limb symmetry indexes for any biomechanical variable after return-to-sport training ( P > .129)., Conclusion: Among those who completed return-to-sport training after ACLR, subsequent quadriceps strength symmetry was not correlated with the persistent asymmetries in gait biomechanics. After a threshold of quadriceps strength is reached, restoring strength alone may not ameliorate gait asymmetries, and current clinical interventions and return-to-sport training may not adequately target gait.

Background: Anterior cruciate ligament injuries are among the most common knee injuries. Mechanism of injury is classified as contact or non-contact. The majority of anterior cruciate ligament ruptures occur through a non-contact mechanism of injury. Non-contact anterior cruciate ligament ruptures are associated with biomechanical and neuromuscular risk factors that can predispose athletes to injuries and may impact future function. Non-contact mechanism of injury may be preceded by poor dynamic knee stability and therefore those with a non-contact mechanism of injury may be prone to poor dynamic knee stability post-operatively. Understanding how mechanism of injury affects post-operative functional recovery may have clinical implications on rehabilitation., Purpose: The purpose of this study was to determine if mechanism of injury influenced strength, functional performance, patient-reported outcome measures, and psychological outlook in athletes at four time points in the first two years following anterior cruciate ligament reconstruction., Study Design: Secondary analysis of a clinical trial., Methods: Seventy-nine athletes underwent functional testing at enrollment after impairment resolution. Quadriceps strength, hop testing, and patient-reported outcome measures were evaluated post-operatively at enrollment, following return-to-sport training and one year and two years after anterior cruciate ligament reconstruction. Participants were dichotomized by mechanism of injury (29 contact, 50 noncontact). Independent t-tests were used to compare differences between groups., Results: There were no meaningful differences between contact and non-contact mechanism of injury in any variables at enrollment, post-training, one year, or two years after anterior cruciate ligament reconstruction., Conclusion: Function did not differ according to mechanism of injury during late stage rehabilitation or one or two years after anterior cruciate ligament reconstruction., Level of Evidence: III., (© 2020 by the Sports Physical Therapy Section.)

Objective: To determine whether the addition of perturbation training to a secondary injury prevention program reduces the rate of second anterior cruciate ligament (ACL) injury compared to the prevention program alone., Design: Single-blinded randomized controlled trial., Methods: Thirty-nine female athletes who intended to return to cutting/pivoting sports were enrolled 3 to 9 months after primary anterior cruciate ligament reconstruction (ACLR). Athletes were randomized to receive a training program of either progressive strengthening, agility, plyometrics, and prevention (SAPP) (n = 20) or SAPP plus perturbation training (n = 19); each had 10 sessions over 5 weeks. Occurrence and side of second ACL injury were recorded for 2 years after primary ACLR., Results: There were 9 second ACL injuries in the 2 years after ACLR. There was no statistically significant difference in rate or side of second ACL injury between the SAPP-plus-perturbation training and SAPP groups., Conclusion: Adding perturbation training to a secondary ACL injury prevention program did not affect the rate of second ACL injury in female athletes. J Orthop Sports Phys Ther 2020;50(9):523-530. Epub 1 Aug 2020. doi:10.2519/jospt.2020.9407 .

Objective: Graft choices for athletes undergoing anterior cruciate ligament reconstruction (ACLR) include bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) autografts and soft tissue allografts. The objective was to assess time to meet clinical milestones by graft type in athletes who completed a return-to-sport (RTS) program after ACLR., Design: Retrospective cohort study., Methods: Seventy-nine athletes enrolled after ACLR (allograft, n = 18; BPTB, n = 24; HT, n = 37). Time from surgery to meet (1) enrollment criteria (12 or more weeks post surgery, 80% or greater isometric quadriceps strength index, minimal effusion, and full knee range of motion), and (2) RTS criteria (90% or greater quadriceps strength index, hop testing limb symmetry, and patient-reported outcomes) was calculated. Quadriceps strength, hop performance, and patient-reported outcomes were measured before and after training, and at 1 year post surgery. Descriptive statistics, chi-square tests, and 1-way analyses of variance ( α = .05) were used to analyze differences among graft types., Results: On average, the BPTB group (28.5 ± 7.6 weeks) took longer to meet enrollment milestones than the HT (22.5 ± 7.6 weeks, P = .007) and allograft (18.9 ± 5.8 weeks, P <.001) groups. The BPTB group (44.7 ± 15.8 weeks) took longer from surgery to meet RTS criteria than the HT (32.5 ± 9.9 weeks, P = .001) and allograft (29.3 ± 9.0 weeks, P <.001) groups. After training, the quadriceps strength index was lower in the BPTB group (86.1% ± 11.4%) than it was in the HT (96.1% ± 12.9%, P = .004) and allograft (96.9% ± 5.9%, P = .009) groups., Conclusion: Athletes with a BPTB autograft may take longer than athletes with an HT autograft or a soft tissue allograft to complete postoperative rehabilitation, recover quadriceps strength, and meet RTS criteria. J Orthop Sports Phys Ther 2020;50(5):259-266. Epub 27 Nov 2019. doi:10.2519/jospt.2020.9111 .

Post-traumatic patellofemoral osteoarthritis (OA) is prevalent after anterior cruciate ligament reconstruction (ACLR) and early cartilage degradation may be especially common in the femoral trochlear cartilage. Determining the presence of and factors associated with early femoral trochlear cartilage degradation, a precursor to OA, is a critical preliminary step in identifying those at risk for patellofemoral OA development and designing interventions to combat the disease. Early cartilage degradation can be detected using quantitative magnetic resonance imaging measures, such as tissue T 2 relaxation time. The purposes of this study were to (i) compare involved (ACLR) versus uninvolved (contralateral) femoral trochlear cartilage T 2 relaxation times 6 months after ACLR, and (ii) determine the relationship between walking speed and walking mechanics 3 months after ACLR and femoral trochlear cartilage T 2 relaxation times 6 months after ACLR. Twenty-six individuals (age 23 ± 7 years) after primary, unilateral ACLR participated in detailed motion analyses 3.3 ± 0.6 months after ACLR and quantitative magnetic resonance imaging 6.3 ± 0.5 months after ACLR. There were no limb differences in femoral trochlear cartilage T 2 relaxation times. Slower walking speed was related to higher (worse) femoral trochlear cartilage T 2 relaxation times in the involved limb (Pearson's r: -0.583, p = 0.002) and greater interlimb differences in trochlear T 2 relaxation times (Pearson's r: -0.349, p = 0.080). Walking mechanics were weakly related to trochlear T 2 relaxation times. Statement of clinical significance: Slower walking speed was by far the strongest predictor of worse femoral trochlear cartilage health, suggesting slow walking speed may be an early clinical indicator of future patellofemoral OA after ACLR. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:645-652, 2020., (© 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Background: Partial meniscectomy dramatically increases the risk for post-traumatic, tibiofemoral osteoarthritis after anterior cruciate ligament reconstruction (ACLR). Concomitant medial meniscus surgery influences walking biomechanics (e.g., medial tibiofemoral joint loading) early after ACLR; whether medial meniscus surgery continues to influence walking biomechanics two years after ACLR is unknown., Research Question: Does medial meniscus treatment at the time of ACLR influence walking biomechanics two years after surgery?, Methods: This is a secondary analysis of prospectively collected data from a clinical trial (NCT01773317). Fifty-six athletes (age 24 ± 8 years) with operative reports, two-year biomechanical analyses, and no second injury prior to two-year testing participated after primary ACLR. Participants were classified by concomitant medial meniscal status: no medial meniscus involvement (n = 36), partial medial meniscectomy (n = 9), and medial meniscus repair (n = 11). Participants underwent biomechanical analyses during over-ground walking including surface electromyography; a validated musculoskeletal model estimated medial compartment tibiofemoral contact forces. Gait variables were analyzed using 3 × 2 ANOVAs with group (medial meniscus treatment) and limb (involved versus uninvolved) comparisons., Results: There was a main effect of group (p = .039) for peak knee flexion angle (PKFA). Participants after partial medial meniscectomy walked with clinically meaningfully smaller PKFAs in both the involved and uninvolved limbs compared to the no medial meniscus involvement group (group mean difference [95%CI]; involved: -4.9°[-8.7°, -1.0°], p = .015; uninvolved: -3.9°[-7.6°, -0.3°], p = .035) and medial meniscus repair group (involved: -5.2°[-9.9°, -0.6°], p = .029; uninvolved: -4.7°[-9.0°, -0.3°], p = .038). The partial medial meniscectomy group walked with higher involved versus uninvolved limb medial tibiofemoral contact forces (0.45 body weights, 95% CI: -0.01, 0.91 BW, p = 0.053) and truncated sagittal plane knee excursions, which were not present in the other two groups., Significance: Aberrant gait biomechanics may concentrate high forces in the antero-medial tibiofemoral cartilage among patients two years after ACLR plus partial medial meniscectomy, perhaps explaining the higher osteoarthritis rates and offering an opportunity for targeted interventions., Level of Evidence: Level III., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Women after anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) are more likely than men to exhibit asymmetric movement patterns, which are associated with post-traumatic osteoarthritis. We developed the ACL specialized post-operative return-to-sports (ACL-SPORTS) randomized control trial to test the effect of strength, agility, plyometric, and secondary prevention (SAPP) training with and without perturbation training (SAPP + PERT) on gait mechanics in women after ACLR. We hypothesized that movement symmetry would improve over time across both groups but more so among the SAPP + PERT group. Thirty-nine female athletes 3-9 months after primary ACLR were randomized to SAPP or SAPP + PERT training. Biomechanical testing during overground walking occurred before (Pre-training) and after (Post-training) training and one and 2 years post-operatively. Hip and knee kinematic and kinetic variables were compared using repeated measures analysis of variance with Bonferroni corrections for post hoc comparisons (α = 0.05). There was a time by limb interaction effect (p = 0.028) for peak knee flexion angle (PKFA), the primary outcome which powered the study, characterized by smaller PKFA in the involved compared to uninvolved limbs across treatment groups at Pre-training, Post-training, and 1 year, but not 2 years. Similar findings occurred across sagittal plane knee excursions and kinetics and hip extension excursion at midstance. There were no meaningful interactions involving group. Neither SAPP nor SAPP + PERT training improved walking mechanics, which persisted 1 but not 2 years after ACLR. Statement of clinical significance: Asymmetrical movement patterns persisted long after participants achieved symmetrical strength and functional performance, suggesting more time is needed to recover fully after ACLR. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1743-1753, 2019., (© 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Background: Outcomes after anterior cruciate ligament reconstruction (ACLR) are not uniformly good and are worse among young female athletes. Developing better rehabilitation and return-to-sport training programs and evaluating their outcomes are essential., Purpose: (1) Test the effect of strength, agility, plyometric, and secondary prevention (SAPP) exercises with and without perturbation training (SAPP + PERT) on strength, hops, function, activity levels, and return-to-sport rates in young female athletes 1 and 2 years after ACLR and (2) compare 2-year functional outcomes and activity levels among young female athletes in the Anterior Cruciate Ligament Specialized Post-Operative Return-to-Sports (ACL-SPORTS) trial to homogeneous cohorts who completed criterion-based postoperative rehabilitation alone (Multicenter Orthopaedic Outcomes Network [MOON]) and in combination with extended preoperative rehabilitation (Delaware-Oslo)., Study Design: Randomized controlled trial, Level of evidence, 1; and cohort study, Level of evidence, 3., Methods: A total of 40 level 1 and level 2 female athletes were enrolled after postoperative impairment resolution 3 to 9 months after primary ACLR. Participants were randomized to 10 SAPP or SAPP + PERT sessions and were tested 1 and 2 years after ACLR on quadriceps strength, hop tests, functional outcomes, and return-to-sport rates. Participants were then compared with homogeneous cohorts of young (<25 years) female athletes who completed criterion-based postoperative rehabilitation alone (MOON) and in combination with extended preoperative rehabilitation (Delaware-Oslo) on 2-year functional outcomes., Results: No significant or meaningful differences were found between SAPP and SAPP + PERT, so groups were collapsed for comparison with the other cohorts. At 2-year follow-up, ACL-SPORTS had the highest scores ( P < .01) on the Marx activity rating scale (ACL-SPORTS, 13.5 ± 3.3; Delaware-Oslo, 12.5 ± 2.7; MOON, 10.6 ± 5.1); International Knee Documentation Committee Subjective Knee Evaluation Form (96 ± 7, 92 ± 9, and 84 ± 14, respectively); and Knee injury and Osteoarthritis Outcome Score (KOOS) subscales for Pain (98 ± 4, 94 ± 9, and 90 ± 10, respectively), Symptoms (94 ± 6, 90 ± 9, and 83 ± 14, respectively), Activities of Daily Living (100 ± 1, 99 ± 4, and 96 ± 7, respectively), Sports and Recreation (94 ± 8, 86 ± 15, and 82 ± 17, respectively), and Quality of Life (89 ± 14, 78 ± 18, and 76 ± 19, respectively). The Patient Acceptable Symptom State threshold on the KOOS-Sports and Recreation was achieved by 100% of the ACL-SPORTS cohort compared with 90% of Delaware-Oslo and 78% of MOON ( P = .011)., Conclusion: Although perturbation training provided no added benefit, 10 sessions of return-to-sport training, compared with criterion-based postoperative rehabilitation alone, yielded statistically significant and clinically meaningfully higher 2-year functional outcomes among young, high-level female athletes after ACLR., Registration: NCT01773317 (ClinicalTrials.gov identifier)., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: Funding provided by the National Institutes of Health: NIH/NIAMS Grant No. R01 AR048212 (L.S.-M.) for the ACL-SPORTS trial; NIH/NICHD Grant No. R37 HD037985 (L.S.-M.) for the Delaware-Oslo Cohort; NIH/NIAMS Grant No. R01 AR053684 (K.P.S.) for the MOON Cohort; and NIH/NICHD Grant No. F30 HD096830 (J.J.C.) for the NRSA predoctoral fellowship award. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. J.J.C.’s work was supported in part by the Foundation for Physical Therapy Promotion of Doctoral Studies, Level I and Level II Scholarships. K.P.S. has received consulting fees from Cytori, the National Football League, and Mitek; research support from Smith & Nephew Endoscopy and DonJoy Orthopaedics; and hospitality payments from DePuy and Biosense Webster. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Background: Gait asymmetry is frequently observed following anterior cruciate ligament reconstruction (ACLR). Psychological readiness to return to sport is associated with functional and activity-related outcomes after ACLR. However, the association between gait asymmetry and psychological readiness to return to sport is unknown., Objectives: To determine the relationship between kinematic and kinetic measures of knee symmetry during gait and psychological readiness to return to sport following ACLR., Methods: In this controlled laboratory, cross-sectional study, 79 athletes (39 women) underwent gait analysis following impairment resolution after ACLR (ie, full range of motion, minimal or no effusion, quadriceps strength index of 80% or greater). Interlimb differences during gait were calculated for sagittal plane knee angles at initial contact, peak knee flexion, and peak knee extension, as well as for peak knee flexion moment and peak knee adduction moment. Athletes completed the Anterior Cruciate Ligament-Return to Sport after Injury scale (ACL-RSI) to assess psychological readiness to return to sport. Pearson correlations were used to examine the association between ACL-RSI score and each gait symmetry variable., Results: Significant negative correlations were observed between the ACL-RSI and 2 kinematic variables: knee flexion angle at initial contact (r = -0.281, P = .012) and peak knee flexion (r = -0.248, P = .027). In general, lower scores on the ACL-RSI were associated with greater interlimb asymmetry., Conclusion: There was a weak association between psychological readiness to return to sport and knee kinematic asymmetry during gait. J Orthop Sports Phys Ther 2018;48(12):968-973. Epub 27 Jul 2018. doi:10.2519/jospt.2018.8084.

Background: The Anterior Cruciate Ligament-Specialized Post-Operative Return to Sports (ACL-SPORTS) randomized controlled trial was designed to address deficits in functional and patient-reported outcomes. The trial examined the effects of a secondary ACL prevention program that included progressive strengthening, agility training, plyometrics (SAP), and other components of current primary prevention protocols, with perturbation training (SAP + PERT group) and without PERT (SAP group). A secondary purpose of this study was to examine whether study outcomes differed between men and women., Hypotheses: (1) Athletes in both the SAP and SAP + PERT groups will have improved knee function and patient-reported outcome measures from pre- to posttraining, (2) the SAP + PERT group would have higher outcome scores than the SAP group, and (3) outcomes will differ by sex., Study Design: Randomized controlled trial (NCT01773317)., Level of Evidence: Level 2., Methods: A total of 79 athletes (39 women) were randomized into the SAP and SAP + PERT groups. All athletes had undergone primary ACL reconstruction and achieved 80% quadriceps strength limb symmetry (QI), full range of motion, had minimal effusion, and had no pain. Additionally, all had begun running again. Prior to and after the training program, athletes' QI, hopping, and patient-reported outcomes were assessed. Repeated-measures analyses of variance were used to determine whether there were differences between groups. Subsequently, the SAP and SAP + PERT groups were collapsed to analyze differences between sexes., Results: There were significant increases for all variables, with the exception of QI. There were no differences between the SAP and SAP + PERT groups. Both men and women made significant improvements in all knee function and patient-reported outcome measures except QI. Men made significant improvements in QI, whereas women did not., Conclusion: The common elements of the training program that all athletes received (10 sessions of progressive strengthening, agility training, plyometrics, and secondary prevention) may be a beneficial addition to the return-to-sport phase of ACL reconstruction rehabilitation. The results suggest that women may require further quadriceps strengthening to maintain and improve QI, an important focus given the relationship between QI and risk for reinjury., Clinical Relevance: During the return-to-sport phase of ACL reconstruction rehabilitation, clinicians tend to shift their focus away from strengthening toward more advanced sports-related tasks. These results indicate that women in particular need continued focus on quadriceps strengthening.

The risk for post-traumatic osteoarthritis is elevated after anterior cruciate ligament reconstruction (ACLR), and may be especially high among individuals with aberrant walking mechanics, such as medial tibiofemoral joint underloading 6 months postoperatively. Rehabilitation training programs have been proposed as one strategy to address aberrant gait mechanics. We developed the anterior cruciate ligament specialized post-operative return-to-sports (ACL-SPORTS) randomized control trial to test the effect of 10 post-operative training sessions consisting of strength, agility, plyometric, and secondary prevention exercises (SAPP) or SAPP plus perturbation (SAPP + PERT) training on gait mechanics after ACLR. A total of 40 male athletes (age 23 ± 7 years) after primary ACLR were randomized to SAPP or SAPP + PERT training and tested at three distinct, post-operative time points: 1) after impairment resolution (Pre-training); 2) following 10 training sessions (Post-training); and 3) 2 years after ACLR. Knee kinematic and kinetic variables as well as muscle and joint contact forces were calculated via inverse dynamics and a validated electromyography-informed musculoskeletal model. There were no significant improvements from Pre-training to Post-training in either intervention group. Smaller peak knee flexion angles, extension moments, extensor muscle forces, medial compartment contact forces, and tibiofemoral contact forces were present across group and time, however the magnitude of interlimb differences were generally smaller and likely not meaningful 2 years postoperatively. Neither SAPP nor SAPP + PERT training appears effective at altering gait mechanics in men in the short-term; however, meaningful gait asymmetries mostly resolved between post-training and 2 years after ACLR regardless of intervention group. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2364-2372, 2018., (© 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Background: Knee osteoarthritis risk is high after anterior cruciate ligament reconstruction (ACLR) and arthroscopic meniscal surgery, and higher among individuals who undergo both. Although osteoarthritis development is multifactorial, altered walking mechanics may influence osteoarthritis progression. The purpose of this study was to compare gait mechanics after ACLR among participants who had undergone no medial meniscal surgery, partial medial meniscectomy, or medial meniscal repair., Methods: This was a secondary analysis of data collected prospectively as part of a clinical trial. Sixty-one athletes (mean age of 21.4 ± 8.2 years) who had undergone primary ACLR participated in the study when they achieved impairment resolution (5.3 ± 1.7 months postoperatively), including minimal to no effusion, full knee range of motion, and ≥80% quadriceps-strength symmetry. Participants were classified by concomitant medial meniscal treatment: no involvement or nonsurgical management of a small, stable tear; partial meniscectomy; or meniscal repair. Participants underwent comprehensive walking analyses. Joint contact forces were estimated using a previously validated, electromyography-driven musculoskeletal model. Variables were analyzed using a mixed-model analysis of variance with group and limb comparisons (α = 0.05); group comparisons of interlimb differences in measurements (surgical minus contralateral limb) were performed to determine significant interactions., Results: The participants in the partial meniscectomy group walked with a higher peak knee adduction moment (pKAM) in the surgical versus the contralateral limb as compared with those in the meniscal repair group and those with no medial meniscal surgery (group difference for partial versus repair: 0.10 N-m/kg-m, p = 0.020; and for partial versus none: 0.06 N-m/kg-m, p = 0.037). Participants in the repair group walked with a smaller percentage of medial to total tibiofemoral loading in the surgical limb compared with both of the other groups (group difference for repair versus partial: -12%, p = 0.001; and for repair versus none: -7%, p = 0.011). The participants in the repair group loaded the medial compartment of the surgical versus the contralateral limb 0.5 times body weight less than did the participants in the partial meniscectomy group., Conclusions: Participants in the partial meniscectomy group walked with higher pKAM and shifted loading toward the medial compartment of the surgical limb, while participants in the repair group did the opposite, walking with lower pKAM and unloading the surgical limb relative to the contralateral limb. These findings may partially explain the conflicting evidence regarding pKAM after ACLR and the elevated risk for osteoarthritis (whether from overloading or underloading) after ACLR with concomitant medial meniscectomy or repair., Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background: The Anterior Cruciate Ligament-Specialized Post-Operative Return to Sports (ACL-SPORTS) randomized control trial (RCT) examined an evidence-based secondary ACL injury prevention training program, involving progressive strengthening, agility training, and plyometrics. The RCT examined the benefit of the training program with and without a neuromuscular training technique called perturbation training., Hypothesis/purpose: The purpose of this study was to report the return to sport and second ACL injury incidence outcomes of the men in the ACL-SPORTS trial., Study Design: Secondary analysis of a RCT., Methods: Forty cutting and pivoting sport male athletes participated in the ACL-SPORTS trial, return to sport testing, and in follow-up sessions at one and two years after ACL reconstruction. Variables of interest at one and two years were return to sport, return to preinjury level of sport, and second ACL injuries. Mean time to passing return to sport criteria, the number of athletes returning to sport and preinjury level of sport and the incidence proportion of second ACL injuries were calculated., Results: Athletes passed return to sport criteria 232 ± 99 days after ACLR. One year after ACL reconstruction 95% had returned to sport, 78% at their preinjury level. Two years after ACL reconstruction all athletes had returned to sport, 95% at their preinjury level and only one athlete had a second ACL injury., Conclusions: The results of this study indicate that men in the ACL-SPORTS trial had much higher return to sport rates and much lower second ACL injury rates than those reported in the literature., Level of Evidence: 1b.

Patellofemoral pain (PFP) is a common diagnosis that includes an amalgam of conditions that are typically non-traumatic in origin and result in peripatellar and/or retropatellar knee pain. The purpose of this review is to provide an overview of the physical therapist's management, including the evaluation and treatment, of the patient with PFP. A thorough history is critical for appropriately diagnosing and optimally managing PFP; the history should include the date of symptom onset, mechanism of injury and/or antecedent events, location and quality of pain, exacerbating and alleviating symptoms, relevant past medical history, occupational demands, recreational activities, footwear, and patient goals. Physical examination should identify the patient's specific impairments, assessing range of motion (ROM), muscle length, effusion, resisted isometrics, strength, balance and postural control, special tests, movement quality, palpation, function, and patient reported outcome measures. Objective assessments should guide treatment, progression, and clinical decision-making. The rehabilitation program should be individually tailored, addressing the patient's specific impairments and functional limitations and achieving the patient's goals. Exercise therapy, including hip, knee, and core strengthening as well as stretching and aerobic exercise, are central to the successful management of PFP. Other complimentary treatments may include patellofemoral and tibiofemoral joint mobilizations, patellofemoral taping, neuromuscular training, and gait retraining. Appropriate progression of interventions should consider objective evaluations (e.g., effusion, soreness rules), systematic increases in loading, and the chronicity of symptoms. Although short-term changes or reductions in movement often are necessary in a protective capacity, the persistence of altered movement is a key characteristic of chronic pain, which may be managed in part through emphasis on function over symptoms, graded exposure, patient education, and perhaps referral. PFP etiology is largely movement related and a comprehensive conservative treatment using movement can be successful., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.

Background: Athletes often are cleared to return to activities 6 months after anterior cruciate ligament (ACL) reconstruction; however, knee function measures continue to improve up to 2 years after surgery. Interventions beyond standard care may facilitate successful return to preinjury activities and improve functional outcomes. Perturbation training has been used in nonoperative ACL injury and preoperative ACL reconstruction rehabilitation, but has not been examined in postoperative ACL reconstruction rehabilitation, specifically return to sport rehabilitation., Questions/purposes: The purpose of this study was to determine whether there were differences at 1 and 2 years after ACL reconstruction between the male SAP (strengthening, agility, and secondary prevention) and SAP+PERT (SAP protocol with the addition of perturbation training) groups with respect to (1) quadriceps strength and single-legged hop limb symmetry; (2) patient-reported knee outcome scores; (3) the proportion who achieve self-reported normal knee function; and (4) the time from surgery to passing return to sport criteria., Methods: Forty men who had completed ACL reconstruction rehabilitation and met enrollment criteria (3-9 months after ACL reconstruction, > 80% quadriceps strength limb symmetry, no pain, full ROM, minimal effusion) were randomized into the SAP or SAP+PERT groups of the Anterior Cruciate Ligament-Specialised Post-Operative Return to Sports trial (ACL-SPORTS), a single-blind randomized clinical study of secondary prevention and return to sport. Quadriceps strength, single-legged hopping, the International Knee Documentation Committee (IKDC) 2000 subjective knee form, Knee Injury and Osteoarthritis Outcome Score (KOOS)-sports and recreation, and KOOS-quality-of-life subscales were collected 1 and 2 years after surgery by investigators blind to group. Athletes were categorized as having normal or abnormal knee function at each time point based on IKDC score, and the time until athletes passed strict return-to-sport criteria was also recorded. T-tests, chi square tests, and analyses of variance were used to identify differences between the treatment groups over time., Results: There were no differences between groups for quadriceps symmetry (1 year: SAP = 101% ± 14%, SAP+PERT = 101% ± 14%; 2 years: SAP = 103% ± 11%, SAP+PERT = 98% ± 14%; mean differences between groups at 1 year: 0.4 [-9.0 to 9.8], 2 years = 4.5 [-4.3 to 13.1]; mean difference between 1 and 2 years: SAP = -1.0 [-8.6 to 6.6], SAP+PERT = 3.0 [-4.3 to 10.3], p = 0.45) or single-legged hop test limb symmetry. There were no clinically meaningful differences for any patient-reported outcome measures. There was no difference in the proportion of athletes in each group who achieved normal knee function at 1 year (SAP 14 of 19, SAP+PERT 18 of 20, odds ratio 0.31 [0.5-19.0]; p = 0.18); however, the SAP+PERT group had fewer athletes with normal knee function at 2 years (SAP 17 of 17, SAP+PERT 14 of 19, p = 0.03). There were no differences between groups in the time to pass return to sport criteria (SAP = 325 ± 199 days, SAP+PERT = 233 ± 77 days; mean difference 92 [-9 to 192], p = 0.09)., Conclusions: This randomized trial found few differences between an ACL rehabilitation program consisting of strengthening, agility, and secondary prevention and one consisting of those elements as well as perturbation training. In the absence of clinically meaningful differences between groups in knee function and self-reported outcomes measures, the results indicate that perturbation training may not contribute additional benefit to the strengthening, agility, and secondary prevention base of the ACL-SPORTS training program., Level of Evidence: Level II, therapeutic study.

Background: Movement asymmetries during walking are common after anterior cruciate ligament (ACL) injury and reconstruction and may influence the early development of posttraumatic osteoarthritis. Preoperative neuromuscular training (like perturbation training, which is neuromuscular training requiring selective muscle activation in response to surface perturbations) improves gait asymmetries and functional outcomes among people who are ACL-deficient, but the effect of postoperative perturbation training on gait mechanics after ACL reconstruction is unknown., Questions/purposes: Among men undergoing ACL reconstruction, we sought to compare strength, agility, and secondary prevention (SAP) treatment with SAP plus perturbation training (SAP+PERT) with respect to (1) gait mechanics; and (2) elimination of gait asymmetries 1 and 2 years after ACL reconstruction., Methods: Forty men were randomized into a SAP group or a SAP+PERT group after ACL reconstruction and before returning to preinjury activities. Participants were required to achieve ≥ 80% quadriceps muscle strength symmetry, minimal knee effusion, full ROM, no reports of pain, and completion of a running progression (all between 3 and 9 months postoperatively) before enrollment. Of 94 potentially eligible athletic male patients evaluated < 9 months after ACL reconstruction, 54 were excluded for prespecified reasons. Participants underwent motion analysis during overground walking at 1 and 2 years postoperatively. Variables of interest included (1) sagittal and frontal plane hip and knee angles and moments at peak knee flexion angle; (2) sagittal plane hip and knee angles and moments at peak knee extension angle; (3) sagittal plane hip and knee excursion during weight acceptance; and (4) sagittal plane hip and knee excursion during midstance. We also calculated the proportion of athletes in each group who walked with clinically meaningful interlimb asymmetry in sagittal plane hip and knee variables and compared these proportions using odds ratios. There was no differential loss to followup between groups., Results: There were no differences between the SAP or SAP+PERT groups for the biomechanical gait variables. The involved limb's knee excursion during midstance for the SAP (mean ± SD: 1 year: 15° ± 5°; 2 years: 16° ± 5°) and SAP+PERT (1 year: 16° ± 5°; 2 years: 15° ± 4°) athletes was not different between groups at 1 year (mean difference: -1°; 95% confidence interval [CI], -5° to 2°; p = 0.49) or 2 years (mean difference: 1°; 95% CI, -2° to 4°; p = 0.54). There were no differences between SAP and SAP+PERT athletes regarding the elimination of gait asymmetries, and gait asymmetries persisted to a large degree in both groups 1 and 2 years postoperatively. At 1 year, 11 of 18 SAP and 11 of 20 SAP+PERT athletes walked with truncated knee excursions during weight acceptance (odds ratio: 0.8, p = 0.70) and midstance (SAP 12 of 18, SAP+PERT 12 of 20; odds ratio: 0.8, p = 0.67), whereas at 2 years postoperatively, truncated knee excursions during weight acceptance (SAP seven of 17, SAP+PERT eight of 19; odds ratio: 1.0, p = 0.96) and midstance (SAP five of 17, SAP+PERT 11 of 19; odds ratio: 3.3, p = 0.09) remained prevalent., Conclusions: We found that a comprehensive, progressive return-to-sport training program with or without perturbation was not effective at restoring interlimb symmetry among men 1 or 2 years after ACL reconstruction. Although gait asymmetries improved from 1 to 2 years postoperatively, meaningful asymmetries persisted in both groups. To restore gait symmetry after ACL reconstruction, additional interventions likely are necessary., Level of Evidence: Level II, therapeutic study.

Second anterior cruciate ligament rupture is a common and devastating injury among young women who return to sport after ACL reconstruction, but it is inadequately understood. The purpose of this study was to compare gait biomechanics and return-to-sport time frames in a matched cohort of young female athletes who, after primary ACLR, returned to sport without re-injury or sustained a second ACL injury. Approximately 6 months after primary reconstruction, 14 young women (age 16 ± 2 years) involved in jumping, cutting, and pivoting sports underwent motion analysis testing after physical therapy and impairment resolution. Following objective return-to-sport clearance, seven athletes sustained a second ACL rupture within 20 months of surgery (13.4 ± 4.9 months). We matched them by age, sex, and sport-level to seven athletes who returned to sports without re-injury. Data were analyzed using a previously validated, EMG-informed, patient-specific musculoskeletal model. Compared to athletes without re-injury, athletes who sustained a second ACL injury received surgery sooner (p = 0.023), had post-operative impairments resolved earlier (p = 0.022), reached criterion-based return-to-sport benchmarks earlier (p = 0.024), had higher body mass index (p = 0.039), and walked with lower peak knee flexor muscle forces bilaterally (p = 0.021). Athletes who sustained a second injury also tended to walk with larger (p = 0.089) and more symmetrical peak knee flexion angles and less co-contraction, all indicative of a more normal gait pattern. Statement of Clinical Significance: Delayed return-to-sport clearance even in the absence of gait or clinical impairments following primary ACL reconstruction may be necessary to mitigate second ACL injury risk in young women. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1894-1901, 2017., (© 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Synopsis The literature pertaining to the rehabilitation of ice hockey players seeking to return to sport after anterior cruciate ligament reconstruction (ACLR) is currently limited. The purpose of this clinical commentary was to present a criterion-based progression for return to ice hockey for athletes after ACLR. First, we review pertinent literature and provide previously published guidelines on general rehabilitation after ACLR. Then, we present a 4-phase, on-ice skating progression with objective criteria to initiate each phase. During the early on-ice phase, the athlete is reintroduced to specific demands, including graded exposure to forward, backward, and crossover skating. In the intermediate on-ice phase, the emphasis shifts to developing power and introducing anticipated changes of direction within a controlled environment. During the late on-ice phase, the focus progresses to developing anaerobic endurance and introducing unanticipated changes of direction, but still without other players or contact. Finally, once objective return-to-sport criteria are met, noncontact team drills, outnumbered and even-numbered drills, practices, scrimmages, and games are progressively reintroduced during the return-to-sport phase. Recommendations for off-ice strength and conditioning exercises complement the on-ice progression. Additionally, we apply the return-to-hockey progression framework to a case report of a female collegiate defensive ice hockey player who returned to sport successfully after ACLR. This criterion-based return-to-hockey progression may guide rehabilitation specialists managing athletes returning to ice hockey after ACLR. J Orthop Sports Phys Ther 2017;47(5):324-333. Epub 29 Mar 2017. doi:10.2519/jospt.2017.7245.