Localization of the semitendinosus-gracilis tendon bifurcation point relative to the tibial tuberosity: an aid to hamstring tendon harvest

Abstract

Purpose: Autologous hamstring grafts are commonly used for knee reconstruction. The proximity of the saphenous nerve and its branches, the superficial medial collateral ligament, and the inherent variability of fascial attachments necessitates effective surgical incision placement to minimize tissue morbidity during graft harvest. This study describes a method of locating the semitendinosus and gracilis tendon bifurcation point relative to the tibial tuberosity. It uses a novel diagonal surgical incision placed between a proximal point placed 3 cm medial to the tibial tuberosity and at 3 cm distal and 5 cm medial to the tibial tuberosity. Type of Study: Descriptive. Methods: Thirty-one cadaveric knees (17 right, 14 left) were placed in a jig at 90° flexion. Reference marks were placed over the tibial tuberosity, at 3 cm medial to the tibial tuberosity, and at 3 cm distal and 5 cm medial to the tibial tuberosity. An approximately 3.5-cm-long line (representing the incision) was drawn connecting the 2 points located medial to the tibial tuberosity. After incision, the semitendinosus and gracilis tendon bifurcation point locations were measured with an inflexible metric ruler (± 0.5 cm) and recorded. Results: The mean bifurcation point was located 2.2 ± 0.7 cm distal and 4.5 ± 0.6 cm medial to the tibial tuberosity, directly on the proposed incision line. All bifurcation points were located within ± 2 cm of the proposed incision. Conclusions: The traditionally used incision line is, on average, located 2 cm too lateral to the bifurcation point and in some cases may be located 3 to 4 cm too lateral, making tendon harvest more difficult and more likely to cause harvest-induced injury to adjacent tissues.