Influence of shelf acetabuloplasty on the outcomes of total hip arthroplasty in hips with dysplasia: a case-control study

Introduction Total hip arthroplasty (THA) in young adults, especially in those with hip dysplasia, is affected by wear and acetabular fixation problems. Shelf acetabuloplasty is performed to delay THA in patients with acetabular dysplasia. Thus, we conducted a retrospective, continuous case-control study at a single healthcare facility to analyze (1) the influence of prior shelf acetabuloplasty on the survival of a subsequent THA and (2) the functional outcomes. Materials and methods We evaluated 105 patients (124 THA) who underwent THA due to hip dysplasia: 54 patients (61 THA) were included in the THA post-shelf acetabuloplasty group (case group) and 51 patients (63 THA) in the THA for dysplasia group (control group). Results At 15 years' follow-up, 89% of patients (95% CI: 84-91%) in the shelf group and 83% (95% CI: 81-90%) in the dysplasia group had not undergone surgical revision. This difference between groups was not statistically significant (p = 0.566). The functional outcomes were satisfactory in both groups; however, they were significantly better in the dysplasia group than in the shelf group based on the Merle d'Aubigne and Postel score (16.9 vs 16.0 min-max: 14-18 vs 3-18) (p = 0.01), Harris Hip score (90.0 vs 84.7, min-max: 62-100 vs 22-100) (p = 0.017), and the Oxford-12 (18/60 vs 21/60, min-max: 45-12 vs 51-12) (p = 0.04). Conclusion Shelf acetabuloplasty before THA does not negatively affect THA survivorship. The functional outcomes appear to be better in the hips that did not undergo shelf acetabuloplasty, although the results were good in both groups.