Arthroscopic Outcomes as a Function of Acetabular Coverage From a Large Hip Arthroscopy Study Group

Abstract

Purpose: To report comparative hip arthroscopic outcomes of patients with low (borderline dysplasia), normal, and high (global pincer femoroacetabular impingement [FAI]) lateral acetabular coverage.

Methods: A retrospective analysis of prospectively collected data from a multicenter registry was performed. Primary hip arthroscopy patients were assigned to 1 of 3 groups based on preoperative lateral center-edge angle: borderline dysplasia (≤25°), normal (25.1°-38.9°), and pincer (≥39°). Repeated-measures analysis of variance compared preoperative with 2-year minimum postoperative International Hip Outcome Tool (iHOT-12) scores. Subsequent analysis of variance determined the effect of acetabular coverage on magnitude of change in scores.

Results: Of 437 patients, the only statistical difference between groups was a lower prevalence of acetabuloplasty in the borderline dysplasia group (P = .001). A significant improvement in the preoperative to postoperative iHOT-12 scores for patients with normal acetabular coverage, acetabular undercoverage, and acetabular overcoverage was observed: F(1, 339) = 311.06; P <.001, with no statistical differences in preoperative (P = .505) and postoperative (P <.488) iHOT-12 scores when comparing the groups based on acetabular coverage. Mean iHOT-12 scores increased from 37.3 preoperatively to 68.7 postoperatively (P <.001) in the borderline dysplasia group, from 34.4 to 72 (P <.001) in the normal coverage group, and from 35.3 to 69.4 (P <.001) in the pincer group. These preoperative scores increased by 31.4, 37.8, and 34.1, respectively, with no effect for acetabular coverage on the magnitude of change from preoperative to postoperative iHOT-12 scores: F(2,339) = 1.18; P = .310. Ten patients (2.3%) underwent conversion arthroplasty, and 19 patients (4.4%) underwent revision arthroscopy with no significant effect of acetabular coverage on the incidence of revision or conversion surgery: χ² (6,433) = 11.535; P = .073.

Conclusions: Lateral acetabular coverage did not influence outcomes from primary hip arthroscopy when performed in patients with low (borderline dysplasia), normal, and high (global pincer FAI) lateral center-edge angle. Borderline dysplasia and moderate global pincer FAI with no or minimal osteoarthritis do not compromise successful 2-year minimum outcomes or survivorship following primary hip arthroscopy when performed by experienced surgeons.

Level of evidence: Level III, retrospective therapeutic trial.