Risk Factors for Early Conversion to Total Hip Arthroplasty following Hip Arthroscopy

OBJECTIVES: The most common reason for reoperation following arthroscopic hip surgery is conversion to total hip arthroplasty (THA). The purpose of this study was to identify clinical and radiographic risk factors for early conversion to THA. METHODS: Data were prospectively collected on all hip arthroscopy patients from January 2009 through December 2011. Inclusion criteria for the study group were patients undergoing hip arthroscopy for a labral tear who eventually converted to THA. Patients were then compared to a control group of patients who underwent hip arthroscopy for a labral tear and did not convert to THA during the same period. Exclusion criteria were patients with previous hip conditions such as Legg-Calves-Perthes, slipped capital femoral epiphysis, pigmented villonodular synovitis, and avascular necrosis. A bivariate analysis of 41 preoperative and intraoperative variables was performed. RESULTS: A total of 792 patients met inclusion and exclusion criteria. A total of 72 (9%) converted to THA. The control group consisted of 720 patients who did not convert to THA. Bivariate analysis demonstrated that the study group had significantly higher means or frequencies than the control group for the following variables: male gender, age at time of surgery, BMI, back pain, previous back surgery, Tönnis grade above 0, acetabular inclination angle, alpha angle, Seldes combined-type labral tear, labral tear size, chondral injury, traction time, labral debridement (versus repair), number of anchors used repair or reconstruction, and capsular release (versus repair). The study group had significantly lower means or frequencies than the control group for the following variables: preoperative patient reported outcome scores, crossover sign, lateral center edge angle, and psoas release. A statistically significant difference in average joint space was not observed. CONCLUSION: Multiple risk factors are possible preoperative and intraoperative risk factors for conversion to THA following hip arthroscopy. The clinician and patient should be aware of these variables.