Quadriceps and hamstring muscles strength differences in adolescent and adult recreational athletes 6 months after autograft bone–patellar-tendon–bone anterior cruciate ligament reconstruction: A retrospective study

Background: Knee muscle strength recovery after anterior cruciate ligament reconstruction (ACLR) is crucial for a safe return to sport (RTS) but it is poorly described in the adolescent population. Therefore, we compared the knee muscle strength at 6 months post-surgery in adults and adolescents. We hypothesized a greater muscular strength in adolescents 6 months after ACLR. Methods: This was a retrospective analysis of 55 adolescents (13–18 years old) and 76 adults (19–39 years old) who underwent ACLR with autograft bone–patellar-tendon–bone (BPTB), subjected to isokinetic tests 6 months after surgery. The following outcomes were analyzed: (1) the maximum torque of hamstrings (H) and quadriceps (Q) during flexion and extension at 30°/s normalized by body weight; (2) hamstrings to quadriceps strength ratio (HQ ratio); (3) injured to uninjured leg muscle strength ratio (limb-symmetry index, LSI). Results: Both adults and adolescents produced lower Q torque with the injured leg compared ...