To The Editor:
We are writing in regard to the Instructional Course Lecture "Controversies in Intramedullary Nailing of Femoral Shaft Fractures" (2001;83:1404-15), by Wolinsky et al. The authors provided useful information; however, the ideal entry point was stated to be the piriformis fossa. We believe that the literature is confusing in regard to the terminology of the entry point.
Although various authors have pointed out that the piriformis fossa is the ideal starting point for antegrade nailing of femoral shaft fractures, the published illustrations consistently highlight the trochanteric fossa
1,2-5 .
The piriformis fossa is located in the anteromedial part of the greater trochanter of the femur
6 . Georgiadis et al.
7 , in a cadaveric study, found that the piriformis fossa is located approximately 2 cm from the posteriormost point of the greater trochanter, and they emphasized the difference between the piriformis fossa and the trochanteric fossa.
On the other hand, the trochanteric fossa of the femur is located in the posterior third of the neck where the obturator internus attaches superiorly and is surrounded by the inferior and superior gemelli muscles with the obturator externus insertion lying just underneath them
6 . The trochanteric fossa coincides with the exact point indicated by the vast majority of the published illustrations as the ideal entry point for intramedullary nailing of the femur, although it is commonly labeled "the piriformis fossa."
1,2-5
We think that this clarification should be highlighted, as the proper entry point is critical to ensure proper nail placement and fracture reduction.
J.D. Heckman replies:
Drs. Papadakis and Shepherd raise an interesting anatomical point. Upon review of the study by Georgiadis et al.
7 , it appears that the starting point for antegrade nailing of the femur used by most trauma surgeons is not the piriformis fossa. Rather, the area that Georgiadis et al. term the trochanteric fossa, or digital fossa, which is the site of insertion of the obturator externus tendon, appears to be the spot that most surgeons recommend. Chapman describes it clearly as ". . . the thin cortex at the base of the greater trochanter, at the site of its junction with the superior aspect of the femoral neck."
8 He further describes this spot as ". . . at the base of the greater trochanter at its junction with the femoral neck in the region of the insertion of the obturator internus. Note that this entry point is neither on the femoral neck nor on the tip of the trochanter."
8 Thus, this area, the trochanteric, or digital, fossa, appears to be the ideal starting point for antegrade insertion of a femoral nail in most patients, and those of us who for years have incorrectly called it the piriformis fossa should change our ways!
P.R. Wolinsky replies:
The standard starting point for intramedullary nailing is the piriformis fossa, which is located in the posterior one-third of the proximal part of the femur. We only briefly mentioned this in the article, and there were no figures that illustrated any starting hole. I am not familiar with the nomenclature of the trochanteric fossa. I thank Drs. Papadakis and Shepherd for raising the issue and for providing this teaching point.