Deep posterior gluteal compartment block for regional anaesthesia of the posterior hip: a proof-of-concept pilot study.

Background: Various regional anaesthesia approaches to branches of the anterior lumbar plexus have been proved effective in providing analgesia in hip surgery. However, some patients still experience significant residual posterior hip pain attributed to the posterior nerve supply of the hip. This not only suggests that anterior approaches may not always provide sufficient pain relief, but also that the blocking of major nerves supplying the posterior pericapsular region is needed. Methods: We present an ultrasound-guided technique to block all major nerves supplying the posterior capsule of the hip joint. The optimal target area was determined by ultrasound imaging, cross-sectional digitised anatomy, and cadaver research, and was found in the deep gluteal compartment. Furthermore, this posterior pericapsular deep-gluteal block was evaluated in two patients. Results: The spread of dye in the cadaver was observed deep to the gluteus maximus and in between the quadratus femoris and piriformis muscles, and conformed to the presumed location during the ultrasound procedure. It included all major supplying nerves to the posterior hip capsule, that is the superior gluteal nerve, nerve to quadratus femoris and sciatic nerve. In both patients where this posterior pericapsular deep-gluteal block was applied the pain was substantially reduced (numeric rating scale: 4 to 1 and 7 to 1). Conclusion: We present a successful ultrasound-guided technique targeting the deep gluteal compartment to block all major nerves supplying the hip joint's posterior capsule. This posterior pericapsular deep-gluteal block can be applied as an additional block in hip surgery, with also a possible role in chronic hip pathology.