Sensory Innervation of the Hip Joint and Referred Pain: A Systematic Review of the Literature.

Objectives: The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches innervating the hip joint and the distribution of sensory receptors within its capsule.

Methods: Five electronic databases were queried, with the search encompassing articles published between January 1945 and June 2019. Twenty-one original articles providing a detailed description of sensory receptors around the hip joint capsule (n=13) and its articular branches (n=8) were reviewed.

Results: The superior portions of the anterior capsule and the labrum were found to be the area of densest nociceptive innervation. Similar to the distribution of nociceptors, mechanoreceptor density was found to be higher anteriorly than posteriorly. Hip joint capsular innervation was found to consistently involve the femoral and obturator nerves, which supply the anterior capsule, and the nerve to the quadratus femoris, which supplies the posterior capsule. The femoral, obturator, and superior gluteal nerves supply articular branches to the most nociceptor-rich region of the hip capsule.

Conclusions: The femoral and obturator nerves and the nerve to the quadratus femoris were found to consistently supply articular branches to both the anterior and posterior capsule of the hip joint. The anterior capsule, primarily supplied by the femoral and obturator nerves, and the superior labrum appear to be the primary pain generators of the hip joint, given their higher density of nociceptors and mechanoreceptors.

Level Of Evidence: Anatomy study, literature review.