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Anterior Inferior Iliac Spine/Subspine Hip Impingement: Physiopathology and Surgical Management

March 01, 2020

Contributors: Sergio Andrés Arroyave Rivera, FACS; Lorena Bejarano-Pineda, MD; Juan Carlos Gomez Hoyos, MD; Francisco Javier Monsalve, MD; Alvaro Vanegas-Gomez, MD; Santiago Vanegas-Alzate, MD; William Henry Marquez, MD

2020 AWARD WINNER Introduction: Subspine hip impingement, or anterior inferior iliac spine (AIIS) impingement, has been described as impingement or abnormal contact between the AIIS and the anterior and inferior portion of the femoral neck during hip movement, which may result in compression of the capsule, labrum, rectus femoris, and iliocapsularis muscles. This impingement occurs with activities that require movements in forced flexion and internal rotation of the hip. AIIS deformities may result from excessive bone formation after avulsion injury of the rectus femoris or a morphologic variant, may cause hip dysfunction, and may benefit from surgical management. Purpose: This video shows the gross anatomy of the anterior hip, including the osseous structures, muscles, tendons, capsule, and acetabular labrum, at rest and during movement in hip flexion. In addition, the video presents the outcomes of arthroscopic decompression of subspine hip impingement. Methods: The video presents the gross anatomy of the anterior portion of the hip at rest and during hip flexion in a cadaver laboratory and demonstrates arthroscopic decompression of the AIIS. The video retrospectively reviews 31 patients with femoroacetabular impingement (FAI) and AIIS/subspine hip impingement who underwent arthroscopic decompression. All the patients had groin pain with movement in forced flexion and internal rotation of the hip. AP radiographs and MRI were used to confirm AIIS morphology in all the patients, five in whom CT also was obtained. Arthroscopic decompression was performed via standard anterolateral and mid-anterior hip arthroscopy portals that also were used to explore the joint and manage concomitant intra-articular pathology. A 4-mm burr was used to decompress the AIIS prominence. The rehabilitation protocol consisted of the use of crutches for 3 weeks postoperatively, allowing for progressive weight bearing and range of motion. Active flexion was not allowed for the first 6 weeks postoperatively. Outcomes were assessed at a mean follow-up of 31 months (range, 10 to 51 months) via the modified Harris Hip Score. Results: A total of 31 patients (18 men, 13 women) with a mean age of 37.7 years (range, 19 to 54 years; standard deviation ± 10.79 years) were included in the study. All the patients had FAI (26 cam-type FAI, 15 pincer-type FAI). A type 2 AIIS (AIIS extends to the level of the rim) was present in 14 patients, and a type 3 AIIS (AIIS extends distally to the acetabular rim) was present in 17 patients. The mean modified Harris Hip Score improved from 61.06 (range, 41 to 87; standard deviation ± 10.07) preoperatively to 93.83 (range, 85 to 100; standard deviation ± 3.84) at final follow-up. Muscle strength was normal in all the patients at final follow-up. Conclusion: Arthroscopic decompression of symptomatic subspine hip impingement in patients with femoroacetabular impingement is an effective treatment option, resulting in excellent outcomes with a high level of pain relief.