Radiographic Comparison of Surgical Hip Dislocation and Hip Arthroscopy for Treatment of Cam Deformity in Femoroacetabular Impingement

Background: Whether open or arthroscopic techniques are employed, the goal of femoroacetabular impingement (FAI) surgery is to achieve impingement-free range of motion. While arthroscopic approaches have improved and gained popularity, an objective evaluation of the surgical correction achieved with this approach compared with open surgery remains to be defined in the literature. Purpose: This study was undertaken to compare the efficacy of arthroscopic osteoplasty and open surgical dislocation in treating FAI dysmorphology in a consecutive series of patients. Study Design: Cohort study; Level of evidence, 3. Methods: Surgical treatment was performed in 60 male patients under 40 years of age for symptomatic FAI refractory to non-operative management. Patients were matched (not randomized) to treatment groups: 30 patients (15 left and 15 right hips) underwent arthroscopic cam and/or rim osteoplasty with labral debridement and/or refixation by an arthroscopic surgeon; and 30 (14 left and 16 right hips) underwent open surgical dislocation, cam and/or rim osteoplasty, and labral debridement or refixation by a hip preservation surgeon. Anteroposterior (AP) pelvis and extended-neck (Dunn) lateral radiographs were obtained and the depth of resection and arc of resection were measured by assessment of anterior femoral head-neck offset, AP and lateral alpha angle, and beta angle on preoperative and postoperative radiographs. Results: In the arthroscopic group, the extended-neck lateral alpha angle was reduced by a mean of 17.2 degrees (28.3%, P < .05), AP alpha angle was reduced by a mean of 12.6 degrees (16.8%), anterior head-neck offset improved 5.0 mm (111%, P < .05), and beta angle increased by a mean of 23.1 degrees. In the open dislocation group, the extended-neck lateral alpha angle was reduced by a mean of 21.2 degrees (30.7%, P < .05), AP alpha angle was reduced by a mean of 20.1 degrees (25.7%), anterior head-neck offset improved 6.56 mm (108%, P <. 05), and beta angle increased by a mean of 18.35 degrees. Conclusion: Arthroscopic osteoplasty can restore head-neck offset and achieve similar depth, arc, and proximal-distal resection with comparable efficacy to open surgical dislocation for anterior and anterosuperior cam and focal rim impingement deformity. The open technique, however, may allow greater correction of posterosuperior loss of femoral offset and may be favorable for FAI patterns that demonstrate considerable proximal femoral deformity on AP radiographs.