Knee flexor strength and endurance profiles after ipsilateral hamstring tendons anterior cruciate ligament reconstruction

Objectives To profile knee flexor strength and endurance responses to ipsilateral hamstring tendon autograft anterior cruciate ligament reconstruction in patients, and to describe knee flexor strength and endurance as predictors of subjective outcomes. The hypothesis was that the involved leg would demonstrate deficits compared with uninvolved and matched legs. Design Retrospective cohort. Setting Controlled laboratory. Participants Women (n=15; mean age, 20.47±1.96y; height, 1.69±.08m; weight, 68.51±12.64kg), who were a mean ± SD of 25.93±11.25 months postsurgery, were matched to 15 sex-matched controls (mean age, 20.93±1.22y; height, 1.65±.06m; weight, 66.52±10.69kg). Interventions Not applicable. Main Outcome Measures Concentric peak flexor moment over the entire isokinetic joint range of motion, peak flexor moment at 105 of joint flexion, and knee flexor total work, normalized to body mass, and subjective questionnaire scores for the involved leg. Results Significantly lesser peak flexor moment over the entire isokinetic joint range of motion (P=.034) and total work (P=.048) existed for the involved leg (.959±.186Nm/kg; 21.933±5.881J/kg) compared with the matched leg (1.108±.134Nm/kg; 27.431±6.499J/kg). Significantly lesser peak flexor moment at 105 of joint flexion (P=.002) existed between the involved (.221±.116Nm/kg) and uninvolved (.40±.234Nm/kg) and matched (.475±.183Nm/kg) legs. Significantly greater strength deficits (P≤.001) existed at peak flexor moment at 105 of joint flexion compared with peak flexor moment over the entire isokinetic joint range of motion for side (53.83%±38.8%; 9.87%±10.77%) and group (77.61%±44.14%; 18.09%±11.73%) differences. Peak flexor moment at 105 of joint flexion was a significant predictor of subjective pain (P=.007), symptoms (P=.006), function (P=.011), and sports (P=.022) outcomes. Conclusions Knee flexor strength and endurance deficits suggest susceptibility to reinjury, and strength in a deep joint angle predicts subjective outcomes.