A safe area and angle for harvesting autogenous tendons for anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) reconstruction with autogenous semitendinosus and gracilis tendons has become a common surgical procedure. Lower leg paresthesia following injury to the infrapatellar nerve during harvesting of the tendons has been well documented. Few authors have described the position of the infrapatellar nerve on a flexed knee, which is the position used during ACL reconstruction. The purpose of this study was to determine a safe area and angle where an incision could be made for harvesting of the semitendinosus and gracilis tendons, with the knee in flexion. Twenty right cadaver knees and 20 left knees were dissected. Landmarks on the knee were identified, from where the distances to the nerves (infrapatellar and saphenous) were measured with a vernier caliper. A safe area on the right knee was determined to be on the tibial tuberosity plane between 3.7 and 5.5 cm with a safe angle of incision of 51.6 degrees. A safe area on the left knee was determined to be on the tibial tuberosity plane between 3.6 and 4.9 cm with a safe angle of incision of 52.5 degrees. The results may assist orthopedic surgeons performing ACL reconstruction with semitendinosus and gracilis tendons to avoid cutaneous nerve damage and, therefore, patient discomfort.