Ultrasound-guided injections for the retrotrochanteric region: A cadaveric investigation

Injections for the piriformis and triceps coxae tendons/bursae have not been described and validated.

To investigate the deep retrotrochanteric anatomy and validate an ultrasound (US)-guided injection technique.

Fifteen sides of the pelvic half/lower limb of formalin-fixed cadaveric specimens were dissected to investigate the deep retrotrochanteric region. An US-guided superficial/peritendinous green latex dye injection was performed on both sides of a single full body cadaver. Next, seven sides of another four full body cadavers were injected using a deep/intrabursal technique. The cadavers were dissected to observe the dye's location.

In the anatomical part of the study, we observed a consistent fusion of the piriformis tendon (PT) with the triceps coxae tendon (TCT) (15/15), and with the gluteus medius tendon in 93% (14/15). A bursa of piriformis was identified in 80% (12/15) of the cases, and a subtendinous bursa of obturator internus was found in 73% (11/15). A fat pad overlying the PT-TCT was present in 93% (14/15) of the cases. Regarding the US-guided injections, success rate for superficial/peritendinous injection was 0% (0/2), with the latex dye being identified in the fat pad covering the PT-TCT in both cases. For the deep/intrabursal injection, the success rate was 86% (6/7).

The results indicated a satisfactory success rate for the deep/intrabursal injection of PT-TCT in retrotrochanteric pain syndrome. This technique holds promise for the treatment of bursa and tendon pathologies in relevant patients.