Total hip arthroplasty outcomes for developmental dysplasia of the hip versus primary osteoarthritis: Older age increases medical, not surgical complications.

Background: Developmental dysplasia of the hip (DDH), the second most common cause of early-onset osteoarthritis (OA), often requires total hip arthroplasty (THA) at a younger age, raising concerns about long-term implant survival and revision risk. Despite previous studies analyzing complication rates following THA, it is still unclear how age influences outcomes in DDH. Methods: Using a national research network, patients who underwent THA from January 1, 2014, to January 1, 2023, were placed into two comparative groups: (1) those undergoing THA for OA secondary to DDH (n = 9695) and (2) those undergoing THA for primary OA (n = 147653). A sub-analysis was conducted comparing THA outcomes in DDH patients aged 18-50 years (n = 2802) versus those aged 50 years and older (n = 6396). Following propensity-score matching, surgical and medical complications were assessed at time periods up to 2 years post-surgery. Results: Our findings demonstrate increased odds of prosthetic dislocation (OR: 1.13, 95 % CI: 1.01-1.27), heterotopic ossification (OR: 2.19, 95 % CI: 1.40-3.42), and anemia (OR: 1.12, 95 % CI: 1.02-1.22) in patients undergoing THA for DDH compared to those undergoing THA for primary OA at 1 year postoperatively across all ages. After propensity-matching, younger DDH patients (18-50 years) had significantly lower odds of deep vein thrombosis (OR: 0.50, 95 % CI: 0.30-0.82), renal failure (OR: 0.54, 95 % CI: 0.40-0.76), and stroke (OR: 0.67, 95 % CI: 0.47-0.97) compared to older DDH patients (age 50+) one year postoperatively. However, odds of surgical complications did not significantly differ between the groups at 90 days, 1 year, or 2 years. Conclusions: THA for DDH showed higher long-term risks of medical and surgical complications compared to OA. Older DDH patients undergoing THA faced increased medical risks with similar surgical complications. THA is suitable for DDH patients of all ages. Future research should integrate radiographic severity and implant-specific data. Level of evidence: Level III Therapeutic Study.