Anatomical Location Of Acetabulum's Lunate Surface

Description

Acetabular lunate surface occupies the peripheral, horseshoe-shaped articular facet of the acetabulum on the lateral aspect of the os coxae. Within the concavity of the socket, the lunate surface forms a smooth crescent that curves superiorly and posteriorly around the acetabular fossa, leaving the nonarticular fossa centrally and the acetabular notch inferiorly. Along the rim, the articular margin sits deep to the fibrocartilaginous acetabular labrum, and the inferior gap at the notch is bridged by the transverse acetabular ligament, completing the ring around the femoral head. Orthopedic teaching often hinges on distinguishing the load-bearing lunate surface from the acetabular fossa, because only the lunate surface carries hyaline cartilage and directly interfaces with the femoral head in the hip joint. That distinction matters in acetabular fractures, where involvement of the superior dome (weight-bearing portion of the lunate surface) predicts post-traumatic osteoarthritis and influences decisions between open reduction and internal fixation versus arthroplasty, and in developmental dysplasia of the hip where deficient superolateral coverage concentrates contact pressures on the remaining lunate cartilage. Surface finish and edge definition in this illustration make the transition from articular facet to fossa and notch easy to teach without conflating rim anatomy with the central depression. A key landmark. Use this illustration in gross anatomy and musculoskeletal radiology curricula when correlating acetabular surface anatomy with CT-based fracture classification, hip arthroscopy portals near the labrum, or surgical approaches to the acetabular rim and dome. Anatomical accuracy verified by SciePro's Medical Advisory Board.