Clinical presentation, imaging findings, and arthroscopic features in skeletally immature and mature adolescent hip patients: a comparative double-cohort retrospective study

The purpose of this study was to evaluate differences in clinical presentation and extent of surgery required based on skeletal maturity between two cohorts of adolescent hip arthroscopy patients. We hypothesized that skeletal immaturity would be associated with a lower frequency of pincer impingement and a decreased need for surgical acetabuloplasty. A database of 1481 hip arthroscopies performed by a single orthopaedic surgeon between 2008 and 2016 was queried. Patients ≤18 years of age with femoroacetabular impingement were divided into two groups based on Risser score: Risser 1–4 (skeletally immature) or Risser 5 (skeletally mature). Groups were compared with respect to presentation, diagnosis, and arthroscopic procedures performed. Eighty-eight skeletally immature and 49 skeletally mature patients were included. Mixed impingement was more common in skeletally mature patients than immature (67.3% vs. 48.9%, P = 0.037). Skeletal maturity was associated with a significantly increased probability of undergoing acetabuloplasty (odds ratio = 4.6, 95% confidence interval 1.4–15.5; P = 0.014). Extent of chondral degeneration was similar between groups. Our findings support the hypothesis that skeletally immature hips undergo acetabuloplasty less frequently and demonstrate similar chondromalacia compared with a skeletally mature cohort. These results suggest that arthroscopic treatment for impingement-associated hip pain may be a reasonable option to consider for symptomatic skeletally immature patients who have completed a structured course of nonoperative treatment. Additional longitudinal outcomes data are needed to clarify the natural history of impingement-associated hip pain in younger populations and whether hip arthroscopy delays progression of osteoarthritis in these patients.