The surgical anatomy of the piriformis tendon, with particular reference to total hip replacement

Abstract

The piriformis muscle is an important landmark in the surgical anatomy of the hip, particularly the posterior approach for total hip replacement (THR). Standard orthopaedic teaching dictates that the tendon must be cut in to allow adequate access to the superior part of the acetabulum and the femoral medullary canal. However, in our experience a routine THR can be performed through a posterior approach without sacrificing this tendon. We dissected the proximal femora of 15 cadavers in order to clarify the morphological anatomy of the piriformis tendon. We confirmed that the tendon attaches on the crest of the greater trochanter, in a position superior to the trochanteric fossa, away from the entry point for broaching the intramedullary canal during THR. The tendon attachment site encompassed the summit and medial aspect of the greater trochanter as well as a variable attachment to the fibrous capsule of the hip joint. In addition we dissected seven cadavers resecting all posterior attachments except the piriformis muscle and tendon in order to study their relations to the hip joint, as the joint was flexed. At flexion of 90° the piriformis muscle lay directly posterior to the hip joint. The piriform fossa is a term used by orthopaedic surgeons to refer the trochanteric fossa and normally has no relation to the attachment site of the piriformis tendon. In hip flexion the piriformis lies directly behind the hip joint and might reasonably be considered to contribute to the stability of the joint. We conclude that the anatomy of the piriformis muscle is often inaccurately described in the current surgical literature and terms are used and interchanged inappropriately.

An appraisal of the short lateral rotators of the hip joint

“…In each of their samples, these muscles attached on the greater trochanter via separate tendons. Roche et al () also observed, in the 15 specimens in their study, no fused tendons but one occurrence of a “double‐tendon.”…”

“…Following the critical analysis of 26 references, Papadakis et al () concluded that the “piriform” and “trochanteric” fossae are different insertion sites for piriformis and OE respectively, hence cannot be interchangeably used. Roche et al () further confirmed the separate insertion of piriformis “away from the trochanteric fossa” in all 15 of their cadaveric sample. Although limited by a small sample size, the findings were significant in that none of the tendon attachment sites corresponded with an apparent depression on the greater trochanter that is often referred to as the piriform fossa (Roche et al, ).…”

“…Roche et al () further confirmed the separate insertion of piriformis “away from the trochanteric fossa” in all 15 of their cadaveric sample. Although limited by a small sample size, the findings were significant in that none of the tendon attachment sites corresponded with an apparent depression on the greater trochanter that is often referred to as the piriform fossa (Roche et al, ). The discrepancy in the attachment needs to be further corroborated.…”

“…Although QF does not contribute to the osteotendinous complex on the greater trochanter, it is still predisposed to acute strains and impingement within the ischiofemoral space (Willick et al, ; Sussman et al, ). Detailed anatomical knowledge of the attachment and the alignment of each of the six short lateral rotator muscles at their bony insertion can better inform surgical approaches for hip reconstruction (Solomon et al, ; Pine et al, ; Ito et al, ; Roche et al, ; Tamaki et al, ), which in turn, can improve the stability of the hip joint postoperatively (Yamaguchi et al, ).…”

“…These muscles, considered as the “rotator cuff” of the hip (Lockhart et al, ; Pine et al, ), are functionally important in providing support and maintaining stability during hip movements (Snijders et al, ; Solomon et al, ; Sinnatamby, ; Marieb et al, ; Sussman et al, ), thus acting as “postural muscles” rather than “prime movers” of the hip joint (Standring, ). These short lateral hip rotators contribute to joint stability by holding the femoral head in the acetabulum (Romanes, ; Moore et al, ; Giphart et al, ; Agur and Dalley, ), aided by ligamentous and capsular structures of the hip joint (Johnston and Warwick, ; Romanes, ; Roche et al, ).…”