Does Severity of Acetabular Dysplasia Influence Clinical Outcomes After Periacetabular Osteotomy?—A Case-Control Study

Background: Detailed characterization of factors influencing post-periacetabular osteotomy (PAO) outcome could guide treatment offered. Methods: Using a prospective, multicenter database of PAOs, 61 hips/patients (51 females) with lesser dysplasia (acetabular index < 15° and lateral center–edge angle > 15°) were case-control matched for age, gender, body mass index, Tönnis grade, and joint congruency (P =.6-.9) with a “comparison group” of pronounced dysplasia (n = 183), aiming to assess whether severity of acetabular dysplasia has an effect on outcome following PAO and/or the ability to achieve desired acetabular correction. Results: At 4 ± 1.5 years, no differences in complication or reoperation rates were detected between the groups (P =.29). Lesser dysplastic hips had inferior Hip Disability and Osteoarthritis Outcome Score, both preoperatively (52 vs 59) and postoperatively (73 vs 78); however, similar improvements were seen. Among the lesser dysplastic hips, those that required a femoral osteochondroplasty at PAO had significantly inferior preoperative Hip Disability and Osteoarthritis Outcome Score (48 ± 18). Increased ability to achieve optimum correction was seen (80% vs 59%, P =.4) in lesser dysplasia. Conclusion: A PAO is safe and efficacious in the treatment of lesser dysplasia. Further study on the identification of the optimum treatment modality for the mildly dysplastic hips with cam deformity is required.