Anatomical Variations Encountered During the Posterior Approach to the Hip Joint

The posterior approach to the hip joint remains widely used for primary total hip arthroplasty because it provides extensive exposure while preserving the abductor mechanism. Safe execution, however, depends on recognizing anatomical variation within the gluteal region. This narrative review synthesizes variations encountered sequentially during posterior hip exposure and organizes them into superficial, muscular, neurovascular, and osseous domains. Key considerations include branching patterns of the posterior femoral cutaneous and superior cluneal nerves, morphological variation in the short external rotators and quadratus femoris, variation in the sciatic nerve-piriformis relationship, persistent embryonic vessels, os acetabuli, and proximal femoral morphology. The evidence base is heterogeneous and is dominated by cadaveric and anatomical studies, with several prevalence estimates derived from small series. Accordingly, reported frequencies should be interpreted in light of study design and sample size. By arranging these findings according to surgical planes and distinguishing documented clinical complications from anatomy-based theoretical risks, this review provides a practical anatomical roadmap for preoperative planning and intraoperative orientation. The direct effect of many variants on surgical outcomes remains uncertain and warrants prospective clinical study.