The Third Trochanter

Case description:

The third trochanter is a boney prominence or tubercule under the greater trochanter in the superior part of the gluteal tuberosity.  The greater and lesser trochanters are the usual anatomic trochanters in hip scanning.  It is important not to mistake a third trochanter for an atypical femoral fracture (AFF).  Compared to an AFF, the third trochanter’s position is lateral, it is not bilateral, it is unchanged over time, there is no endosteal reaction, no fracture line, and no symptoms.

Credit: Hologic images courtesy of Sarah L Morgan, MD, RD, CCD

References:

• Lozanoff, S., P.W. Sciulli, and K.N. Schneider, Third trochanter incidence and metric trait covariation in the human femur. J Anat, 1985. 143: p. 149-59.

• Bolanowski, W., et al., The occurrence of the third trochanter and its correlation to certain anthropometric parameters of the human femur. Folia Morphol (Warsz), 2005. 64(3): p. 168-75.

• Nayak G, Das SR, Panda SK, Kumari BS.  The third trochanter of femur- An anatomical study.  Int J Cur Res Rev 2020. 23: 126-128. (http://ijcrr.com/uploads/3176_pdf.pdf)