Minimally invasive posterior approach in the popliteal fossa for semitendinosus and gracilis tendon harvesting: an anatomic study.

INTRODUCTION: Harvesting the semitendinosus (ST) and gracilis (GR) tendons at the anteromedial side of the knee may be hampered by a conjoint tendon insertion on the tibial metaphysis and an accessory bundle between the ST and the medial gastrocnemius. Locating and sparing the terminal branches of the saphenous nerve are difficult on an anteromedial approach. The principal objective of the present anatomic study was to assess the feasibility of ST and GR harvesting from a minimally invasive posterior approach in the popliteal fossa. The secondary objective was to analyze the risk of saphenous nerve branch lesion during harvesting.

METHOD: Ten cadaver knees, free of scarring, were used. The whole body was positioned supine. The tendons were located in the popliteal fossa with the knee in 30° flexion. A mini-incision was performed in the fossa. The ST and GR tendons were located, and retrograde followed by anterograde stripping was performed. Tendon lengths and diameters were measured. The knees were then dissected to check for saphenous nerve branch lesions (anterior, infrapatellar and posterior branches).

RESULTS: The GR and ST tendons were respectively located at 14.4 and 24 mm from the medial edge of the knee. In 90% of cases, there was an accessory ST bundle toward the medial gastrocnemius muscle, 26 mm below the posterior edge. Tendons could be harvested without deviation of the stripper. Knee dissection did not find any saphenous nerve branches, these being protected by the sartorius fascia.

DISCUSSION: Posterior ST and GR tendon harvesting in the popliteal fossa is reliable and reproducible. It allows easy sectioning of the accessory ST bundle, without deviation during retrograde stripping. Unlike anterior harvesting, which leads to a rate of saphenous branch lesion of 50-78%, posterior harvesting protects the nerve branches by keeping away from the sartorius.

LEVEL OF EVIDENCE: Level 4.