Background: Multiple reports have detailed clinical outcomes in surgically treated patients with borderline hip dysplasia. The purpose of this systematic review was to define patient outcomes following these surgical interventions.Methods: Searches were developed using an iterative process of gathering and evaluating terms. Comprehensive strategies including both index and keyword methods were devised for the following databases: PubMed, Embase, and Cochrane CENTRAL. Independent review and data abstraction was performed by two authors. Inclusion criteria were clear delineation of outcomes for patients with borderline hip dysplasia (Lateral center edge angle (LCEA) 18-25°) and outcomes following hip arthroscopy and/ or periacetabular osteotomy (PAO), including patient reported outcomes (PROs), revision arthroscopy, and conversion to Total Hip Arthroplasty. Exclusion criteria included alternative surgical procedures including "shelf" or "salvage" osteotomies, studies without patient outcomes or clearly delineated results for patients with borderline dysplasia, inclusion of <5 borderline patients, or inadequate follow-up defined as < 12 months.Results: Thirteen of 2109 articles met inclusion criteria for full data analysis. 505 patients (mean age 29.6 years, 67.7% female) with borderline dysplasia (mean LCEA 22.3°) were treated with hip arthroscopy. The majority of studies reported outcomes using the modified Harris Hip Score (mHHS) and Hip Outcome Score Sports Specific Subscale (HOS-SSS); all showed post-operative improvement with mean increase of 21.0 and 26.8 points, respectively. Revision arthroscopy rate was 7.5% (31/412), and a total hip arthroplasty conversion rate was 4.0% (18/455). The average combined total reoperation rate was 13.7% (69/505).Conclusion: Arthroscopic management of borderline hip dysplasia is associated with meaningful improvement in PRO scores. However, there appears to be a high reoperation rate including both arthroscopic and open revision procedures. There is a paucity of studies reporting outcomes of PAO in patients with borderline hip dysplasia.Level of evidence: Systematic review of Level III and Level IV studies.
Arthroplasty, Replacement, Hip Arthroscopy