Do children <3years at index surgery for DDH have a better outcome at mid-term follow-up in comparison to children >3years at index surgery? A prospective comparative study.

Background: Diagnosis and management of developmental dysplasia of hip (DDH) in underdeveloped regions is frequently delayed, potentially impacting final outcomes. This prospective study was conducted with the aim of answering the question, "Do children <3 years at index surgery for DDH have better outcome at 5-year follow-up in comparison to children >3 years at index surgery?"

Methods: Between 2016 and 2021, all walking-age children with DDH were prospectively enrolled in the study. The study cohort was divided into 2groups: Group 1 ⩽3 years of age, and Group 2 included children >3 years old. Intraoperative decisions determined the need for addition of femoral or pelvic osteotomy to the open reduction (OR). Follow-up assessment and group comparison included acetabular-index (AI), proximal femoral growth disturbances (PFGD), and outcomes based on Severin's criteria. Subgroup analysis also compared re-dislocated hips with stable hips post-surgery. Children with follow-ups <3 years were excluded.

Results: 45 hips in 38 children analysed (31 in Group 1 and 14 in Group 2). Group 1 had higher pre-op AI (p = 0.0489). More hips in Group 2 underwent OR with femoral osteotomy (p = 0.0016). Re-dislocation occurred in 6 (19%) in Group 1 and 2 (14%) in Group 2. Subgroup analysis revealed higher index postoperative AI in re-dislocated hips (p = 0.0001). At the final follow-up, AI was similar between Groups 1 and 2 (p = 0.27). Overall, satisfactory outcomes were comparable between Groups 1 and 2 (p = 0.21). PFGD changes were significantly higher in Group 2 (p = 0.028) and in re-dislocated hips (p = 0.004). Satisfactory outcomes were found in 89% of non-re-dislocated hips and 75% of re-dislocated hips.

Conclusions: At an average follow-up of 5 years, children above and below 3 years at index procedure for DDH show similar outcomes but older ones need femoral osteotomy more frequently. Osteonecrosis risk rises with increasing age at index surgery and after re-operations, but its impact is not clear in mid-term.