Abstract
Background:
In anterior approaches for total hip arthroplasty (THA), the femoral part of the procedure requires the release of the capsule from the greater trochanter. However, it is unknown whether any other tendons of the short external rotator muscles are also damaged during capsular release procedures. The aim of this cadaveric study was to identify the bony landmarks on the greater trochanter, which indicate the individual short external rotator muscle insertions.
Methods:
Forty-four hip regions from 28 embalmed cadavers were dissected. At first, micro-computed tomography (micro-CT) images were obtained to identify bony impressions on the greater trochanter. Then, the soft tissues around the greater trochanter were removed and their insertions were identified to assess correlation with micro-CT images.
Results:
Using micro-CT, three clear impressions were identified on the greater trochanter of cadavers: 1) a shallow groove on the tip of the greater trochanter; 2) a deep, wide depression and groove in the anterior part of the trochanteric fossa; and 3) a deep fovea in the posterior part of the trochanteric fossa (figure B). After removal of the soft tissues around the greater trochanter, the first impression was identified as the insertion of the piriformis and the groove running along its tendon, the second impression as the insertion of the obturator internus, the gemelli and the groove running along their tendons, and the third as the impression of the insertion of the obturator externus (figure C).
Figure legends A: Photographs of the anteromedial aspect of a right proximal femur showing the muscular and tendinous structures around the greater trochanter. B: Micro CT image of the same specimen after the femoral head was removed, showing the three-dimensional conformation of the greater trochanter. The shallow groove on the tip of the greater trochanter (yellow area) was identified as the insertion of the piriformis and the course of its tendon (asterisk). The deep, wide groove on the medial aspect of the greater trochanter (pink area) was identified as the insertion of the obturator internus and the course of its tendon (star). The deep depression on the medial aspect of the greater trochanter, just posterior to the insertion of the obturator internus (blue area) was identified as the insertion of the obturator externus. C: Photograph of the same specimen, after chemical removal of the soft tissue, showing tendon insertions and the course of the short external rotator muscles. The groove adjacent to the insertion of the piriformis (asterisk) indicates the course of its tendon. The groove adjacent to the insertion of the obturator internus (dagger) indicates the course of its tendon. Fh = femoral head, Pi = piriformis, Oi = obturator internus, Oe = obturator externus, Ant = anterior, and Sup = superior.
Conclusions:
Bony landmarks indicating the attachment site and the course of the short external rotator muscles were identified on the greater trochanter.
