Standing flexion deficits predict self-reported outcomes in women after ipsilateral hamstring anterior cruciate ligament reconstruction

Purpose To profile the standing flexion angle and its association with subjective outcomes in ipsilateral hamstring tendon autograft anterior cruciate ligament-reconstructed patients. A secondary aim was to describe prone position-measured hamstring strength as a predictor of flexion angle. Methods Fifteen women (mean age, 20.47 ± 1.96 years; mean height, 1.69 ± 0.08 m; mean weight, 68.51 ± 12.64 kg; mean Tegner score, 6.80 ± 1.52), at a mean of 25.93 ± 11.25 months after surgery, were matched to 15 healthy participants by sex and approximate age, height, mass, and activity level (mean age, 20.93 ± 1.22 years; mean height, 1.65 ± 0.06 m; mean weight, 66.52 ± 10.69 kg; mean Tegner score, 6.13 ± 1.06). The independent variable was leg condition (involved, uninvolved, or matched). Dependent variables included goniometric flexion angle, Knee Injury and Osteoarthritis Outcome Score (KOOS) subscale scores, and absolute isokinetic hamstring strength. We used 1-tailed paired and 2-sample t tests to analyze side and group differences, respectively. Corresponding effect sizes (d) were also quantified. Linear regression assessed relations between flexion angle and the KOOS, as well as strength and flexion angle. P <.05 denoted statistical significance. Results The involved leg showed a significantly lesser flexion angle (112.9 ± 8.1) compared with the uninvolved leg (116.1 ± 8.4, P =.024) and matched leg (117.1 ± 4.5, P =.044), with corresponding weak side (d = 0.380) and strong group (d = 0.958) effect sizes. Significant associations existed between flexion angle and subjective outcomes (r ² = 60.3% and P =.001 for KOOS pain subscale, r² = 37.8% and P =.015 for KOOS subscale for function in activities of daily living, and r² = 39.2% and P =.012 for KOOS subscale for function in sports and recreation) for the involved leg. Hamstring strength was not a significant predictor of flexion angle for all legs (P >.05). Conclusions Our results support the hypotheses that standing flexion angle insufficiencies exist for the involved leg, superior subjective outcomes are associated with greater flexion capacity, and hamstring strength at deep knee angles does not predict the standing flexion angle. Level of Evidence Level IV, therapeutic study, case series.