Primary hip arthroscopy and conversion to total hip arthroplasty: trends and survival analysis in the Medicare population

Introduction: With limited evidence on national incidences of hip arthroscopy in the elderly population, the current study aims to investigate trends of primary hip arthroscopies being performed in the elderly population, using the US Medicare database, and determine risk factors for conversion to total hip arthroplasty (THA). Methods: Medicare Standard Analytic Files were queried using CPT codes to retrieve records of primary hip arthroscopies done for degenerative pathology during 2005-2014. Overall and age-stratified trends in the incidence of hip arthroscopy over time were analysed. Kaplan Meier survival curves were used to assess the overall 2-year conversion rate to a THA. Cox regression analysis was implemented to study risk factors for conversion. Results: 8100 primary hip arthroscopies for degenerative pathology were performed during 2005-2014. There was a 280% increase in overall incidence of arthroscopy. The most commonly performed arthroscopic procedure was for chondroplasty and/or resection of labrum, with 4712 (58.1%) procedures. Around 18.5% patients underwent arthroplasty within 2 years after primary arthroscopy. Following Cox regression an existing diagnosis of osteoarthritis, ages 65-69, ages 70-74, and arthroscopies done in the West were associated with higher risk of conversion to THA within 2 years. Undergoing a repeat arthroscopy was not significantly associated with a higher risk of conversion. Conclusions: Despite inconclusive clinical evidence, hip arthroscopies are being increasingly used in patients older than 65 in the Medicare population. We conclude that patients in the age bracket of 65-74 years and with a pre-existing diagnosis of osteoarthritis, arthroscopy should be approached with caution.