The THA-10 Score for Predicting Conversion to Total Hip Arthroplasty After Contemporary Hip Arthroscopy for Femoroacetabular Impingement Syndrome at a Minimum 10-Year Follow-up

Abstract

Background:

Previous studies have identified predictors of total hip arthroplasty (THA) conversion after hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS) at short- to midterm follow-up, yet no studies to the authors’ knowledge have established a scoring system for predicting THA conversion at a minimum 10-year follow-up.

Purpose:

To create a scoring system to predict 10-year THA conversion after contemporary HA for FAIS.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Data were prospectively collected from patients undergoing primary contemporary HA for FAIS, including labral repair, osteoplasty of FAIS deformity, and capsular repair, between January 2012 and October 2013, with a minimum 10-year follow-up. Patients who underwent THA conversion were compared with patients who achieved 10-year THA-free survivorship. Significant predictors of THA conversion were identified, and predictor weights were assigned to create the THA-10 score. The score was applied to the cohort, and its clinical utility was evaluated. The threshold score with the greatest sensitivity and specificity for predicting 10-year THA conversion was identified.

Results:

In total, 280 patients were included; 21 (7.5%) underwent THA conversion by the 10-year follow-up. Patients who underwent THA conversion were of older age (45.4 ± 11.3 vs 33.2 ± 12.1 years; P < .001), had a greater body mass index (28.0 ± 5.2 vs 24.8 ± 4.7 kg/m²; P = .011), and had a greater prevalence of Tönnis grade 1 osteoarthritis (42.9% vs 14.3%; P = .003) and high-grade acetabular (61.9% vs 12.7%; P < .001) and femoral head (33.3% vs 7.3%; P < .001) chondral defects compared with THA-free survivors. After variable weighting, the THA-10 score was established as 1 point for body mass index ≥25 kg/m², 1 point for Tönnis grade 1, 2 points for age ≥47 years, and 3 points for high-grade defects of the acetabulum or femoral head. The THA-10 score was found to have clinically significant diagnostic value with an area under the receiver operating characteristic curve of 0.823. Patients scoring ≥4 points were 13.2 times more likely to undergo THA conversion (95% CI, 5.0-35.1; P < .001).

Conclusion:

This study created the THA-10 score and showed it to have clinically significant diagnostic utility in predicting 10-year THA conversion after HA for FAIS. Patients scoring ≥4 points were 13.2 times more likely to undergo THA conversion.