Pre-existing osteoarthritis remains a key feature of arthroscopy patients who convert to total hip arthroplasty.

ABSTRACT

OBJECTIVES: To determine the rate of conversion to total hip arthroplasty following ipsilateral hip arthroscopy by a single surgeon in New Zealand and to describe patient-related and surgical characteristics of patients who converted. METHODS: A retrospective cohort analysis of hip arthroscopy patients with 2 years of minimum follow-up identified the total hip arthroplasty conversion rate using the New Zealand National Joint Registry. Prospective data collected from patients who subsequently converted to hip arthroplasty included sex, age at arthroscopy, body mass index, side of hip arthroscopy and arthroplasty, duration of symptoms and patient-reported outcome measures. Imaging (Tönnis grade and lateral centre-edge angle) and surgical findings (labral, ligamentum teres and osteochondral pathology) along with the arthroscopic procedures performed were also documented. RESULTS: Sixty-six out of 1856 (3.56%) primary hip arthroscopies were followed by an ipsilateral hip arthroplasty during the follow-up period (mean 87 ± 29 months). Most patients had pre-existing osteoarthritis and/or chondral lesions (n=51). Dysplasia and over-resection of the acetabulum were also identified as contributing factors. CONCLUSION: Conversion rate by a high-volume surgeon in New Zealand was relatively low. Most patients had pre-existing osteoarthritis and/or chondral lesions that became apparent at arthroscopy. Dysplasia is also a factor to be cautious of when selecting patients for arthroscopy. Acetabular resection must be approached cautiously. LEVEL OF EVIDENCE Level IV.