Assessment of Flexion Strength Following Single- Versus Double-Hamstring Tendon Harvest for Anterior Cruciate Ligament Reconstruction

Purpose: To compare isometric hamstring strength deficits, knee laxity, functional outcomes, and patient-reported outcomes between patients who underwent anterior cruciate ligament (ACL) reconstruction with doubled semitendinosus and gracilis tendon autograft (ST/G) versus quadrupled semitendinosus autograft (ST), at a minimum follow-up of 1-year postoperatively. Methods: Patients who underwent ACL reconstruction with ST/G or ST hamstring autografts were retrospectively identified. Isometric hamstring strength was tested with a hand-held dynamometer at 30, 60, and 90° of knee flexion. Anterior knee laxity was assessed using a KT-1000 arthrometer. Functional outcomes were collected using the single-leg hop test and single-leg squat test. Side-to-side differences were determined and compared between the ST/G and ST groups. Patient-reported outcomes were collected on all patients. Results: Eighty-four patients who underwent ST/G (n = 34) or ST (n = 50) autograft ACL reconstruction were recruited to participate in this study. There was no difference in knee laxity between the groups. Side-to-side hamstring strength deficits increased with increased flexion angles. At 90° of flexion, the ST/G group had a significantly greater flexion strength deficit compared with the ST group (37.8 ± 15.1% vs 24.7 ± 12.5%, P < .001). Aside from a significant difference in the KOOS pain Score (P .045), no other significant differences in functional or patient reported outcomes between the groups were identified. Conclusions: Patients who underwent ACL reconstruction with ST/G compared with ST autograft have a significantly greater isometric flexion strength deficit at 90° of flexion. Future investigations are required to determine the clinical relevance of this difference and whether specialized therapy protocols can mitigate this deficit. Level of Evidence: Level III, retrospective comparative study.