Global Versus Focal Pincer Femoracetabular Impingement: Comparative Outcomes from Arthroscopic Treatment

Abstract

Pincer femoroacetabular impingement occurs in two forms: focal and global, the latter considered more severe and often treated with open surgical dislocation. We use a multicenter prospective design to investigate if any differences in arthroscopic surgical outcome are seen between these two subtypes. A prospective design comparing global (center-edge angle 40+) versus focal pincer cohorts (CEA 20-39) with 2-year minimum follow-up using the nonarthritic hip score (NAHS) and patient satisfaction was implemented at 3 community hospitals. Preoperative clinical and radiographic findings, intraoperative findings and surgical procedures, and postoperative NAHS at 3-, 12- and 24-post-operative months were obtained and inter-group comparisons were made. Complications, revision surgeries, and conversion hip arthroplasties were compared between groups. Multivariate statistical analysis was performed. Further subanalysis was performed on any variable trending toward significance to detect any interaction effect not observed in initial multivariate analyses. The Global cohort consisted of 15 patients (18 hips, 66.7% male) of mean age 37.2 years. The mean NAHS was 51.5 before surgery and 64.2, 66.0, and 74.1 at 3, 12, and 24+ months post-surgery, of which the change in final NAHS was significant (P= 0.01). Mean satisfaction on a 5-point Likert scale was 4.2. There was 1 THA conversion (5.5%) and no revision FAI surgeries or complications. The Focal cohort consisted of 126 patients (130 hips, 48.5 % male) of mean age 40.2 years. The mean NAHS was 54.8 before surgery and 68.3, 76.0, and 76.9 at 3, 12, and 24+ months post-surgery, of which the change in final NAHS was significant (P< 0.0001). Mean satisfaction on a Likert scale was 4.2. There were 9 THA conversions (6.9%), 3 complications (2.3%), and 2 revision FAI surgeries (1.6%). Comparison between cohorts revealed no statistically significant difference in 3, 12, or 24+ month NAHS (P>0.24), no statistically significant difference in 24+ month satisfaction (P=0.97), and no statistically significant difference in THA conversion rate (P= 0.83). Moreover, of the variables we investigated (i.e., age, gender, BMI, Outerbridge grade, Tonnis grade, and time to surgery from pain onset), no variable was found to be a statistically significant predictor of poorer outcomes in the change from preop to 24 months model. Statistical subanalysis detected an interaction effect seen only in the global subtype; women had a more significant change in NAHS than men. Arthroscopic surgery for global deformities may be safely performed using arthroscopic techniques with outcomes comparable to those with lesser focal deformities. However, a gender-specific effect detected only in the global cohort may give men a more guarded prognosis.