The Impact of Age on Outcomes Following Secondary Reconstructive Surgery for Residual Dysplasia in DDH.

BACKGROUND

After reduction of developmental hip dislocations, residual dysplasia is common with rates of secondary reconstructive surgery with pelvic osteotomy ranging from 19% to 60%. The determination and timing of when to proceed with surgery is difficult as acetabular remodeling occurs gradually over the first few years after reduction. The purpose of this study was to evaluate how age at secondary reconstructive surgery influences the clinical and radiographic outcomes after pelvic osteotomy for residual dysplasia.

METHODS

After IRB approval, we retrospectively reviewed all isolated Salter or Pemberton pelvic osteotomies performed for residual dysplasia after an index closed or open reduction at a single institution between 1983 and 2020 with radiographic follow-up through skeletal maturity. Acetabular index (AI) and migration index (MI) were measured on preoperative, immediate postoperative, and 2-year follow-up radiographs. After triradiate cartilage closure, anterior-posterior pelvis radiographs were measured for lateral center-edge angle (LCEA), Tönnis angle, MI, and lateralization ratio (LR). Univariate and multivariate analysis were used to evaluate outcomes based on age at time of surgery.

RESULTS

Ninety-two hips from 83 patients were included. 55 Salter (60%) and 37 Pemberton osteotomies (40%) were performed with mean age at surgery of 5.2±1.7 years. 46% (42/92) hips across both treatment groups had residual dysplasia (LCEA<25 deg.) at final follow-up (mean age 15±3.2 y). However, there was no significant difference in acetabular dysplasia at 2 years postop or after triradiate closure between those hips treated before or after 5 years of age (all P>0.05). Multivariate analysis revealed that only the immediate postoperative MI predicted the final follow-up LCEA (P<0.01), although the rate of dysplasia was still 24% in the most covered hips (MI<10%).

CONCLUSIONS

Even after pelvic osteotomy for residual dysplasia, there are high rates of dysplasia at skeletal maturity. Only the femoral head coverage achieved, not the age at time of surgery, predicted dysplasia at skeletal maturity. These findings suggest that there is no opportunity cost to short-term continued observation while monitoring for acetabular remodeling.

LEVEL OF EVIDENCE

Level III.