Radiographic Comparison of Anterior Acetabular Rim Morphology Between Pincer Femoroacetabular Impingement and Control

摘要

Purpose: To define and compare 3 new parameters (anterior rim angle [ARA], anterior wall angle [AWA], and anterior margin ratio [AMR]), in addition to the lateral center-edge angle of Wiberg and the Tonnis angle, for measuring pincertype femoroacetabular impingement (FAI) in an asymptomatic versus symptomatic FAI population. Methods: We reviewed anteroposterior pelvis radiographs of patients verified to have no hip complaints between December 2009 and December 2011. We also reviewed anteroposterior pelvis radiographs of patients who underwent a rim-trimming procedure for pincer FAI between December 2010 and December 2011. Patients aged older than 65 years or younger than 18 years were excluded. Radiographs with a Tonnis grade of 2 or greater were also excluded. For the group of patients with symptomatic hip impingement, radiographs that did not have a crossover sign were excluded. The 2 cohorts were matched for age, sex, and body mass index. Measurements included the Tonnis angle, lateral center-edge angle of Wiberg, ARA, AWA, and AMR. These measurements were compared between the groups. Results: Seventy-two asymptomatic hips were measured. There were 44 female patients (61%) and 28 male patients (39%), aged 25 to 51 years, in the asymptomatic group. The mean ARA was 88.91 degrees +/- 8.06 degrees, the mean AWA was 34.89 degrees +/- 8.09 degrees, and the mean AMR was 0.49 degrees 0.15. Seventy-two symptomatic hips were measured. There were 40 female patients (56%) and 32 male patients (44%), aged 27 to 58 years, in the symptomatic group. The mean ARA was 82.98 degrees +/- 10.82 degrees, the mean AWA was 39.11 degrees +/- 9.00 degrees, and the mean AMR was 0.56 +/- 0.14. The mean difference in the ARA between asymptomatic patients and symptomatic patients was 5.92 degrees (P = .0001). The mean difference in the AWA was 4.22 degrees (P = .0019). The mean difference in the AMR was 0.07 (P = .0039). Conclusions: Our study provides information on several measurements within an asymptomatic cohort and a symptomatic cohort. Although we found statistically significant differences between the 2 populations, the clinical significance remains unknown. We recommend using this asymptomatic population as a guideline for limits on resection of the anterior acetabular rim.