The safe zones for endoscopic proximal hamstring repair: a cadaveric assessment of standard portal placement and their relationship to major neurovascular structures

Purpose: To define the anatomical relationship of the major neurovascular structures to the standard endoscopic portals used in endoscopic hamstring repair. A secondary outcome was to determine the safest angle of insertion from each standard portal. Methods: Endoscopic portals were established in the 3 standard locations (lateral, medial, and inferior) and Steinmann pins inserted at various angles. Each hip was dissected and the distance between the pins and the pertinent anatomy measured. Results: The lateral portal placed the sciatic and posterior femoral cutaneous (PFC) nerves at greatest risk: direct injury to the sciatic nerve was seen in 11/30 (37%) of the lateral portals sited. A lateral portal with an approach at 60° was the most dangerous orientation with a mean distance of 0.36 ± 0.49 mm and 4.30 ± 2.69 mm from the sciatic and PFC nerves, respectively ( p < 0.001). The 60° medial portal was the safest of all portals measured, at a mean distance of 67.37 ± 11.06mm (range, 47–78 mm) from the sciatic nerve and 58.90 ± 10.57 mm (range 40–70 mm) from the PFC nerve. Conclusions: While currently described techniques recommend establishing the standard lateral portal first, this study shows that it carries the highest risk of injury if used blind. We recommend that the standard medial endoscopic portal is established first to identify the neurovascular structures and minimise iatrogenic neurovascular injury. The inferior and lateral portals can then be established created under direct vision. The lateral portal should be inserted in a more horizontal orientation to decrease the risk of nerve injury.