The proximal origin of the hamstrings and surrounding anatomy encountered during repair. A cadaveric study.

Background: Avulsion of the proximal origin of the hamstrings has become a more frequently recognized athletic injury. Most orthopaedic surgeons rarely operate in this anatomic area. The purpose of the present study was to define the anatomy of the proximal origin of the hamstrings and its relationship to neurovascular and muscular structures encountered during a repair of a complete avulsion.

Methods: Fourteen fresh-frozen hip-to-foot human cadaveric specimens were dissected in the prone position. The proximal origin of the hamstrings and its relationship to the surrounding neurologic and muscular structures were documented and measured with use of digital calipers.

Results: Six of the fourteen specimens were from female donors. The average age of the donors at the time of death was 68 +/- 13 years. The average height of the donors was 66 +/- 3.5 in (167 +/- 8.9 cm), and the average weight was 142 +/- 39 lb (64 +/- 17.7 kg). The semitendinosus and biceps femoris have a common tendinous site of origin on the ischium. A number of measurements were obtained. The musculotendinous junctions of the semitendinosus and biceps femoris separated at an average of 9.9 +/- 1.5 cm from the most proximal origin site on the ischium. The average distance from the proximal border of the semitendinosus/biceps femoris origin to the inferior border of the gluteus maximus was 6.3 +/- 1.3 cm. At the lateral border of the ischium, the average distance from the inferior gluteal nerve and artery to the inferior border of the gluteus maximus was 5.0 +/- 0.8 cm. The sciatic nerve was an average of 1.2 +/- 0.2 cm from the most lateral aspect of the ischial tuberosity. The site of origin of the semitendinosus/biceps femoris was oval, with average measurements of 2.7 +/- 0.5 cm from proximal to distal and of 1.8 +/- 0.2 cm from medial to lateral. The site of origin of the semimembranosus was crescent-shaped, with average measurements of 3.1 +/- 0.3 cm from proximal to distal and of 1.1 +/- 0.5 cm from medial to lateral.

Conclusions: The semitendinosus and biceps femoris have a common tendon of origin on the ischium, and the semimembranosus originates just laterally. The proximal origin of the hamstrings has intimate relationships with the inferior gluteal nerve and artery and the sciatic nerve, which may be at risk during surgical dissection and retraction.