Piriformis Fossa – An Anatomical and Orthopedics Consideration

The external obturator footprint as a landmark in total hip arthroplasty through a direct anterior approach: a CT-based analysis

“…Therefore, this landmark cannot be used as a general indicator of the femoral axis, which is consistent with the literature. 11 However, it may help to identify severe varus or valgus malalignment of the stem during surgery by comparing the distance of the footprint to the shoulder of the stem on the preoperative X-ray.…”

“…9,10 This piriformis fossa is the anatomical site of the EO insertion and is unrelated to the piriformis muscle, but is rather named for its somewhat pear-shaped appearance. 11 In our study we consistently use the term 'EO footprint' for the insertion of the EO tendon. While in our experience the EO footprint is visible on conventional radiographs in the majority of cases in, no data are available on this and the exact position and dimension of the EO footprint has not been described.…”

Optimal entry point for antegrade and retrograde femoral intramedullary nails

“…Lakhwani et al. 20 noted in their anatomical cadaveric study that the piriformis fossa was neither piriform in shape nor the site of the insertion of the piriformis muscle. The muscle is inserted in a small area in the tip of the greater trochanter whereas the piriformis fossa is a depression in the medial aspect of the greater trochanter and is the insertion of the obturator externus.…”

“…The author concluded that the piriformis muscle and fossa are 2 different entities and that the so-called piriformis fossa should be termed as “trochanteric” or “obturator” fossa for clear and correct anatomical description. 20 This confusion in terminology was again addressed by Ansari Moein et al. 8 , where they advised after researching the terminology of antegrade femoral entry points, to re-introduce the original term “trochanteric fossa” in the literature instead of “piriformis fossa”.…”