Risk Factors for Failure of Hip Arthroscopy in Patients with Borderline Dysplasia include a Tönnis angle ≥ 15 degrees, Age ≥ 40-42 years, Female Sex, Anterior Wall Index < 0.35, Labral Debridement, and Preexisting Hip Osteoarthritis: A Systematic Review.

Purpose: To systematically review the literature to determine potential risk factors for failure of hip arthroscopy (HA) in patients with borderline hip dysplasia (BHD).

Methods: A systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines by searching PubMed, the Cochrane Library, and Embase to identify English language clinical studies reporting on patients with BHD undergoing HA from 2003 to 2023. The search terms used were: (borderline OR mild) AND hip AND (arthroscopy OR dysplasia) AND failure. The primary outcomes assessed were risk factors reported by each study for failure of a HA-only approach in BHD patients.

Results: Fourteen studies (8 level III, 6 level IV) met inclusion criteria, totaling 749 hips. Patient age ranged from 29.8 to 39.2 years with a mean follow-up ranging from 24.0 to 144.0 months. The overall percentage of females ranged from 11.8 to 100.0%. Overall, the clinical failure rate ranged from 0 to 53.3% and the reoperation rate ranged from 0 to 44.0%. The predominant predictors of poor outcomes following HA alone included Tönnis angle ≥ 15°, age ≥ 40-42 years at surgery, and female sex. Other risk factors for failure were preoperative clinical arthritis, grade 3 or 4 articular cartilage changes to the femoral head or acetabulum, an anterior wall index (AWI) < 0.35, and labral debridement. Revision procedures performed included revision HA (n=88, 0-28.0%), total hip arthroplasty (n=55, 0-23.7%), and endoscopic shelf acetabuloplasty (n=5, 0-11.0%). One study included an additional 9 patients converting to either PAO or total hip arthroplasty (THA) without distinguishing between the two.

Conclusion: For patients with BHD, Tönnis angle ≥ 15°, age ≥ 40-42 years at surgery, female sex, AWI < 0.35, labral debridement, and preexisting hip osteoarthritis are common risk factors for treatment failure following isolated HA.

Level of evidence: IV, systematic review of level III-IV studies.