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Trochanteric Fossa

fossa trochanterica

The trochanteric fossa is a deep pit on the medial surface of the greater trochanter, at the posterior junction of the intertrochanteric crest with the greater trochanter. It provides the insertion for the tendon of the obturator externus muscle. The fossa lies immediately posterior to the insertion of the piriformis and superior gemellus on the superior facet of the greater trochanter, and medial to the insertions of the gluteus medius and minimus.

Region: Pelvis & Hip

Clinical Relevance

Clinical Notes

The trochanteric fossa is the reference landmark for hip arthroplasty stem version: in cemented hemiarthroplasty, the obturator externus insertion at the trochanteric fossa guides the surgeon to restore the calcar-trochanteric distance and stem anteversion. In posterior hip approaches, the obturator externus tendon is divided from the trochanteric fossa as part of the posterior capsule repair to provide improved stability. Avascular necrosis patterns from femoral neck fractures involve the blood supply traversing the retinacular fibres at the posterior femoral neck just proximal to the trochanteric fossa.

Pathology

Common Injuries & Conditions

Trochanteric Fossa Reference in Hip Arthroplasty

Restoration of correct femoral stem anteversion during hip arthroplasty uses the trochanteric fossa as an anatomical landmark, with the stem version set to align the femoral neck at 15 degrees anteversion relative to the posterior condylar axis, preventing dislocation from mal-rotation.