Paper 12: Severity of Chondrolabral Junction Degeneration Predicts Conversion to Total Hip Arthroplasty after Arthroscopic Femoroacetabular Impingement Treatment at Minimum 10-Years Follow-Up

OBJECTIVES: To identify location and severity of intraoperative pathology at time of arthroscopic surgery for femoroacetabular impingement (FAI) as risk factors for conversion to total hip arthroplasty (THA) utilizing long-term follow-up (minimum 10 years). METHODS: Retrospective study of prospectively collected data of adult patients (≥ 18 years) who underwent hip arthroscopy for FAI between 1998 and 2011 with minimum follow-up of 10 years. Location and severity of pathology at time of arthroscopic surgery were assessed as risk factors for later conversion to a primary outcome of THA. Patients with radiographic evidence of hip dysplasia and previous history of hip surgery were excluded. Patients were then grouped according to whether they had underwent THA. Differences in continuous variables including age, BMI, and center edge angle (CEA) were analyzed with independent t tests. Differences in categorical variables including type of treatment (debridement or repair), deformity (CAM vs pincer vs combined), Outerbridge grade, location of most severe chondral wear (anterosuperior acetabulum, posterosuperior acetabulum, femoral head), presence of chondral flap, and degree of chondrolabral degeneration (as measured by Beck classification) were analyzed with the Pearson’s Chi-squared test. For variables with greater than two levels (chondrolabral degeneration, etc.) adjusted residuals were calculated to determine which comparisons were statistically different, with a value of >2 indicating a lack of fit with the null hypothesis of difference. A multivariable logistic regression model was constructed to estimate the influence of the exact location and severity of pathology on risk for conversion to THA. Model results are reported as odds ratios (OR) with corresponding 95% confidence intervals. RESULTS: A total of 109 patients with a mean age of 39.41 ± 11.43 years and minimum follow-up of 10 years were eligible for inclusion in this study. The average follow-up was 12.29 ± 2.53 years. Average body mass index (BMI) was 26.19 ± 4.07 while average center edge angle (CEA) was 39.53 ± 7.24. 67 (61.5%) patients underwent debridement while 42 (38.5%) patients underwent labral repair. 32 (29.4%) patients subsequently converted to THA. BMI (1.7% difference, p = 0.072), CEA (0.3% difference, p = 0.832), sex (0.2% difference, p = 0.991), procedure type (11.8% difference, p = 0.565), and presence of a chondral flap (6.3% difference, p = 0.685) were not significantly associated with conversion to THA. FAI type, Outerbridge grade, chondrolabral junction degeneration, and location of most severe degenerative change were statistically significant, with adjusted residuals greater than 2 (Table 1). A multivariable logistic regression model demonstrated age (OR=1.08, 95% CI 1.03-1.14, p = 0.002), Grade 4 chondrolabral degeneration (OR = 3.26, 95% CI 1.16-9.17, p = 0.025) and combined FAI type (OR = 4.32, 95% CI 1.38 – 13.56, p = 0.012) as significant risk factors for conversion to THA. CONCLUSIONS: Grade 4 degeneration of the chondrolabral junction as well as combined FAI type and older age are significant risk factors for conversion to THA after arthroscopic treatment of FAI at minimum 10-years of follow-up.