BackgroundArthroscopic hip surgery is becoming increasingly popular for the treatment of femoroacetabular impingement and labral tears. Reports of outcomes of hip arthroscopy converted to total hip arthroplasty (THA) have been limited by small sample sizes. The purpose of this study was to investigate the impact of prior hip arthroscopy on THA complications. MethodsWe queried our institutional database from January 2005 and December 2017 and identified 95 hip arthroscopy conversion THAs. A control cohort of 95 primary THA patients was matched by age, gender, and American Society of Anesthesiologists score. Patients were excluded if they had undergone open surgery on the ipsilateral hip. Intraoperative complications, estimated blood loss, operative time, postoperative complications, and need for revision were analyzed. Two separate analyses were performed. The first being intraoperative and immediate postoperative complications through 90-day follow-up and a second separate subanalysis of long-term outcomes on patients with minimum 2-year follow-up. ResultsAverage time from hip arthroscopy to THA was 29 months (range 2-153). Compared with primary THA controls, conversion patients had longer OR times (122 vs 103 minutes, P = .003). Conversion patients had a higher risk of any intraoperative complication (P = .043) and any postoperative complication (P = .007), with a higher rate of wound complications seen in conversion patients. There was not an increased risk of transfusion (P = .360), infection (P = 1.000), or periprosthetic fracture between groups (P = .150). When comparing THA approaches independent of primary or conversion surgery, there was no difference in intraoperative or postoperative complications (P = .500 and P = .790, respectively). ConclusionConversion of prior hip arthroscopy to THA, compared with primary THA, resulted in increased surgical times and increased intraoperative and postoperative complications. Patients should be counseled about the potential increased risks associated with conversion THA after prior hip arthroscopy.