Transient inferior over-reduction after open reduction in walking-age DDH: A retrospective analysis of 42 Hips.

BACKGROUND

Due to various policy and health infrastructure issues, it is not uncommon to present developmental dysplasia of hip(DDH) at walking-age in India. The purpose of this study was retrospective analysis of operated cases of walking-age DDH with "inferior over-reduction".

METHODS

was defined as break in the Shenton's arc inferiorly in an operated hip which otherwise appears reduced. After Ethical Committee approval, we searched children operated for walking-age DDH. Children suggestive of syndromic association were excluded. We collected demographic data, follow-up, procedures performed, inferior over-reduction and complications. The IHDI grade, Acetabular Index(AI), Smith's ratio for superior (h/b) & lateral displacement(c/b) of femur, and clinical outcome (Modified McKay criteria) were evaluated. The outcomes of cases with inferior over-reduction() were compared with those without().

RESULTS

42 patients with average follow-up of 23 months were enrolled. 21 hips belonged to Group A. By 6 months follow up, all these cases recovered. On comparison of Smith's ratio, group A had significantly higher c/b for the operated hip at 3-month follow-up(p < 0.05). Patients undergoing acetabuloplasty had significantly lower c/b versus all other groups(p < 0.05). Correlation between h/b or c/b with age did not show any significant finding. 15 cases in group A and 14 cases in group B had excellent outcome as per modified McKay's criteria. None of the patients had inferior over-reduction, inferior or obturator dislocation at final follow-up. Three patients with group B had re-dislocation with poor outcome. we recorded 3 hips with AVN (7%).

CONCLUSIONS

This study highlights that after OR of walking-age DDH, the inferior over-reduction may be noted in as much as 50% of the cases. However, this is transient, and all cases recover by the 6 months follow up. There is no significant difference between group A & B in functional outcome, AVN rate. Long-term studies are required to see outcome differences between two groups.