The anterior recess of the hip joint is the redundant anterior capsular fold that accommodates hip extension without capsular tightening. In hip flexion the recess becomes taut, and in extension the redundant fold is taken up. The anterior recess is bordered medially by the iliofemoral ligament and laterally by the pubofemoral ligament. It communicates with the iliopsoas bursa in approximately 10-15% of individuals.
The anterior hip capsule and its recess are the primary targets for hip joint aspiration and intra-articular injection using the anterior approach, performed under ultrasound guidance with the needle directed to the anterior femoral head-neck junction where the capsule is most accessible. Anterior hip capsule distension from effusion is visualised on ultrasound as anterior capsule bulging. Femoroacetabular impingement involves the anterior recess capsule, which becomes fibrotic and contributes to the reduced range of motion. Anterior hip arthroscopy portals access this recess for synovectomy and labral repair.
Hip joint effusion from infection, trauma, inflammatory arthritis, or FAI produces anterior capsule bulging visible on ultrasound, diagnosed by aspiration for cell count and culture; the anterior recess is the preferred site for ultrasound-guided aspiration and cortisone injection.
Chronic anterior hip impingement in cam or pincer FAI leads to anterior capsule scarring and loss of the anterior recess redundancy, reducing hip extension and internal rotation; arthroscopic capsulotomy releases the fibrotic anterior capsule to restore motion.
