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OBJECTIVE: The objective of this study was to examine the association of quadriceps strength symmetry and surgical status (ACL reconstruction or nonoperative management) with early clinical knee OA 5 years after ACL injury or reconstruction. METHODS: 204/300 athletes were analyzed 5 years after ACL injury or reconstruction (ACLR). Quadriceps strength was measured and reported as a limb symmetry index. We identified participants with early clinical knee OA using criteria that two of four Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales score ≤85% (Luyten et al. 2018). We calculated odds ratios (OR) and 95% confidence intervals (CI) using logistic regression, adjusted for age, sex, meniscal injury, and BMI, to examine the associations between quadriceps strength and surgical status with clinical knee OA. RESULTS: 21% of participants met KOOS criteria for clinical knee OA (Luyten et al. 2018). For every 1% increase in quadriceps limb symmetry index, there was 4% lower odds of clinical OA (adjusted OR 0.96, 95% CI 0.93–0.99) at 5 years. Surgical status was not associated with clinical knee OA (adjusted OR 0.58, 95% CI 0.23, 1.50). CONCLUSIONS: More symmetrical quadriceps strength, but not surgical status, 5 years after ACL injury or reconstruction was associated with lower odds of clinical knee OA.

BACKGROUND: Performing physical activities on compliant surfaces alters joints kinematics by decreasing joint motions. However, the effect of administering a training program on a compliant surface on muscle activities after anterior cruciate ligament (ACL) injury is unknown. HYPOTHESIS/PURPOSE: To compare the effects of training on a compliant surface and manual perturbation training on individual muscle activation and muscle co-contraction indexes after an ACL injury. It was hypothesized that patients who received training on the compliant surface would demonstrate higher individual and combined muscle activities compared to the manual group. METHOD: Sixteen patients (participated in level I/II sports) who sustained an ACL injury and had not undergone reconstructive surgery participated in this preliminary study. Eight patients received training on a compliant surface (Compliant group) and data of eight patients matched by age and sex from a previous study who received manual perturbation training were used as a control group (Manual group). Patients in both groups completed standard three-dimensional gait motion analysis with surface electromyography (EMG) of several lower extremity muscles during gait. Muscle co-contraction index and individual muscle activations were computed during weight acceptance (WA) and mid-stance (MS) intervals. A 2x2 analysis of variance (ANOVA) was used with an alpha level of p

BACKGROUND: Some athletes demonstrate excellent dynamic stability after anterior cruciate ligament (ACL) rupture and return to sport without ACL reconstruction (copers). Others demonstrate persistent instability despite rehabilitation (non-copers) and require surgical stabilization. Testing to determine coper classification can identify potential copers early after rupture. It is unclear how coper classification changes after a brief intervention, and how early classification relates to long-term outcomes. HYPOTHESIS/PURPOSE: (1) To evaluate the consistency of early coper classification (potential coper vs. non-coper) before and after progressive neuromuscular and strength training (NMST) in athletes early after acute ACL rupture and (2) to evaluate the association of early coper classification with two-year success after ACL rupture. STUDY DESIGN: Prospective cohort study METHODS: This was a prospective analysis from the Delaware-Oslo ACL cohort study, a cohort of athletes consecutively enrolled early after ACL rupture. Participants (n=271) were tested and classified as potential copers or non-copers using established criteria before and after a 10-session NMST program. Success two years after ACL reconstruction (ACLR) or non-operative rehabilitation (Non-Op) was defined as meeting/exceeding sex- and age-matched norms for knee function, no ACL graft rupture, and ≤1 episode of giving way within the previous year. McNemar’s test evaluated changes in coper classification pre- to post-training. Logistic regression adjusted for baseline characteristics was used to evaluate the association of early coper classification and surgical status with two-year success. RESULTS: Of 300 athletes enrolled, 271 (90%) completed the post-training data collection and 219 (73%) returned for the two-year follow-up. The coper classifications were different between timepoints; nearly half of those classified initially as non-copers became potential copers (p

Supplemental material, DS_10.1177_0363546519825500 for Coper Classification Early After Anterior Cruciate Ligament Rupture Changes With Progressive Neuromuscular and Strength Training and Is Associated With 2-Year Success: The Delaware-Oslo ACL Cohort Study by Louise M. Thoma, Hege Grindem, David Logerstedt, Michael Axe, Lars Engebretsen, May Arna Risberg and Lynn Snyder-Mackler in The American Journal of Sports Medicine

Context: Many coaches, parents, and children believe that the best way to develop elite athletes is for them to participate in only 1 sport from an early age and to play it year-round. However, emerging evidence to the contrary indicates that efforts to specialize in 1 sport may reduce opportunities for all children to participate in a diverse year-round sports season and can lead to lost development of lifetime sports skills. Early sports specialization may also reduce motor skill development and ongoing participation in games and sports as a lifestyle choice. The purpose of this review is to employ the current literature to provide evidence-based alternative strategies that may help to optimize opportunities for all aspiring young athletes to maximize their health, fitness, and sports performance. Evidence Acquisition: Nonsystematic review with critical appraisal of existing literature. Study Design: Clinical review. Level of Evidence: Level 4. Conclusion: Based on the current evidence, parents and educators should help provide opportunities for free unstructured play to improve motor skill development and youth should be encouraged to participate in a variety of sports during their growing years to influence the development of diverse motor skills. For those children who do choose to specialize in a single sport, periods of intense training and specialized sport activities should be closely monitored for indicators of burnout, overuse injury, or potential decrements in performance due to overtraining. Last, the evidence indicates that all youth should be involved in periodized strength and conditioning (eg, integrative neuromuscular training) to help them prepare for the demands of competitive sport participation, and youth who specialize in a single sport should plan periods of isolated and focused integrative neuromuscular training to enhance diverse motor skill development and reduce injury risk factors. Strength of Recommendation Taxonomy (SORT): B.

Context: There is increased growth in sports participation across the globe. Sports specialization patterns, which include year-round training, participation on multiple teams of the same sport, and focused participation in a single sport at a young age, are at high levels. The need for this type of early specialized training in young athletes is currently under debate. Evidence Acquisition: Nonsystematic review. Study Design: Clinical review. Level of Evidence: Level 4. Conclusion: Sports specialization is defined as year-round training (greater than 8 months per year), choosing a single main sport, and/or quitting all other sports to focus on 1 sport. Specialized training in young athletes has risks of injury and burnout, while the degree of specialization is positively correlated with increased serious overuse injury risk. Risk factors for injury in young athletes who specialize in a single sport include year-round single-sport training, participation in more competition, decreased age-appropriate play, and involvement in individual sports that require the early development of technical skills. Adults involved in instruction of youth sports may also put young athletes at risk for injury by encouraging increased intensity in organized practices and competition rather than self-directed unstructured free play. Strength-of-Recommendation Taxonomy (SORT): C.

Manual perturbation training improves dynamic knee stability and functional performance after anterior cruciate ligament rupture (ACL-rupture). However, it is limited to static standing position and does not allow time-specific perturbations at different phase of functional activities. The purpose of this study was to investigate whether administering mechanical perturbation training including compliant surface provides effects similar to manual perturbation training on knee functional measures after an acute ACL-rupture. Sixteen level I/II athletes with ACL-ruptures participated in this preliminary study. Eight patients received mechanical (Mechanical) and eight subjects received manual perturbation training (Manual). All patients completed a functional testing (isometric quadriceps strength, single-legged hop tests) and patient-reported measures (Knee Outcome Survey-Activities of Daily Living Scale (KOS-ADLS), Global Rating Score (GRS), International Knee Documentation Committee 2000 (IKDC 2000) at pre- and post-training. 2 × 2 ANOVA was used for data analysis. No significant group-by-time interactions were found for all measures (p 0.18). Main effects of time were found for single hop (Pre-testing: 85.14% ± 21.07; Post-testing: 92.49% ± 17.55), triple hop (Pre-testing: 84.64% ± 14.17; Post-testing: 96.64% ± 11.14), KOS-ADLS (Pre-testing: 81.13% ± 11.12; Post-testing: 88.63% ± 12.63), GRS (Pre-testing: 68.63% ± 15.73; Post-testing: 78.81% ± 13.85), and IKDC 2000 (Pre-testing: 66.66% ± 9.85; Post-testing: 76.05% ± 14.62) (p 0.032). Administering mechanical perturbation training using compliant surfaces induce effects similar to manual perturbation training on knee functional performance after acute ACL-rupture. The clinical significance is both modes of training improve patients' functional-performance and limb-to-limb movement symmetry, and enhancing the patients' self-reported of knee functional measures after ACL rupture. Mechanical perturbation that provides a compliant surface might be utilized as part of the ACL rehabilitation training. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1391-1397, 2018.