Restoration of symmetric quadriceps strength after ACL reconstruction is associated with more symmetric mechanics during a single-leg drop-landing movement. However, this appears to be multifactorial, as the high-quadriceps group also demonstrated landing asymmetries. Restoration of symmetric quadriceps strength may improve postoperative athletic participation; however, future study is warranted.

Rupture of the anterior cruciate ligament (ACL) is a devastating injury that occurs with high frequency among individuals who participate in cutting and pivoting sports. 24,48 Anterior cruciate ligament reconstruction is commonly performed with the goal of facilitating return to sports activities. However, recent metaanalysis data from over 7000 participants following ACL reconstruction demonstrated that 65% returned to their previous level of sport and only 55% returned to competitive sports.3 Factors associated with a higher rate of return to preinjury level of sport participation were younger age, male sex, positive psychological U U STUDY DESIGN: Prospective cohort study. U U BACKGROUND: While meeting objective criterion cutoffs is recommended prior to return to sports following anterior cruciate ligament (ACL) reconstruction, the number of young athletes who meet recommended cutoffs and the impact of cutoffs on longitudinal sports participation are unknown. U U OBJECTIVES:To test the hypothesis that a higher proportion of young athletes who meet recommended cutoffs will maintain the same level of sports participation over the year following return-to-sport clearance compared to those who do not meet recommended cutoffs. U U METHODS:At the time of return-to-sport clearance, the International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC), quadriceps and hamstring strength limb symmetry index (LSI), and single-leg hop test LSI were assessed. Proportions of participants who met individual (IKDC score of 90 or greater; strength and hop test LSIs of 90% or greater) and combined cutoffs were calculated. Proportions of participants who continued at the same level of sports participation over the year following returnto-sport clearance (assessed using the Tegner activity scale) were compared between those who met and did not meet cutoffs. U U RESULTS:Participants included 115 young athletes (88 female). The proportions meeting individual cutoffs ranged from 43.5% to 78.3%. The proportions meeting cutoffs for all hop tests, all strength tests, and all combined measures were 53.0%, 27.8%, and 13.9%, respectively. A higher proportion of participants who met cutoffs for both strength tests maintained the same level of sports participation over the year following return-tosport clearance than those who did not (81.3% versus 60.2%, P = .02). U U CONCLUSION:The proportions of young athletes after ACL reconstruction recently cleared for return to sports who met the combined criterion cutoffs were low. Those who met the criterion cutoffs for both strength tests maintained the same level of sports participation at higher proportions than those who did not. U U LEVEL OF EVIDENCE: Prognosis, level 2b.

Level II, Prospective cohort study.

Young athletes after ACLR with asymmetries in knee kinematics at the time of RTS reported decreased self-reported function 2 years later; however, the clinical importance of these differences needs to be further understood.

Hamstring strength asymmetry is common at 3 years after ACLR with a hamstring tendon autograft and affects involved knee mechanics during gait and jogging. Additional research is warranted to further investigate the longitudinal effect of these alterations on knee function and joint health after ACLR.

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Background: The impact of maturation on lower extremity strength and function after anterior cruciate ligament reconstruction (ACLR) may help guide future studies of age-specific rehabilitation. Hypothesis Pediatric ACLR patients would demonstrate higher thigh strength symmetry and knee-related function at return to sport (RTS) compared with adolescent and young adult participants who underwent traditional ACLR. Study Design: Prospective cohort study. Level of Evidence: Level 2. Methods: A total of 144 young athletes at the time of RTS clearance post-ACLR were classified into 3 maturational groups (pediatric, n = 16 with physeal-sparing ACLR [mean age = 12.3 years; range = 9.2-14.6 years]; adolescent, n = 113 [mean age = 16.5 years; range = 14.1-19.8 years]; young adult, n = 15 [mean age = 22.0 years; range = 20.5-24.9 years]). Quadriceps and hamstring strength were measured using an electromechanical dynamometer. Knee-related function was measured using the International Knee Documentation Committee (IKDC) subjective form and single-leg hop tests. The Limb symmetry Index (LSI) was used in calculations for hop and strength tests. Group differences were compared with Kruskal-Wallis tests and Mann-Whitney U post hoc tests. Proportions of participants meeting literature-recommended RTS criterion cutoffs were compared among the groups using chi-square tests. Results: The pediatric group demonstrated higher quadriceps LSI ( P = 0.01), IKDC scores ( P < 0.01), single-hop LSI ( P < 0.01), and crossover-hop LSI ( P = 0.02) compared with the young adult group. In addition, the pediatric group demonstrated higher IKDC scores ( P < 0.01) and single-hop LSI ( P = 0.02) compared with the adolescent group. The adolescent group demonstrated higher IKDC scores ( P < 0.01), single-hop LSI ( P = 0.02), and crossover-hop LSI ( P = 0.03) compared with the young adult group. The proportions of participants meeting all RTS criterion cutoffs were highest in the pediatric group and lowest in the young adult group ( P = 0.03). Conclusion: Young athletes at RTS clearance after pediatric ACLR demonstrated higher quadriceps strength symmetry and knee-related function than adolescents and young adults after traditional ACLR. Clinical Relevance: These findings demonstrate the need for further study regarding the impact of these group differences on longitudinal outcomes after ACLR, including successful RTS and risk of second ACL injury.

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