Late reduction in congenital dislocation of the hip and the need for secondary surgery: radiologic predictors and confounding variables

Abstract

Background: Despite early recognition and appropriate treatment of congenital dislocation of the hip, there are a number of cases that subsequently require further surgery to prevent progressive dysplasia, instability, and eventual early osteoarthritis. This study aimed (1) to determine the incidence of pelvic osteotomy (PO) after late open (OR) or closed (CR) reduction for failed initial conservative treatment or late presentation; (2) study potential radiologic predictors of those that will require a secondary procedure; (3) and to evaluate the effect of potential confounding variables including age of reduction, Pavlik harness treatment, and surgical experience on PO rate.

Methods: All cases of congenital dislocation of the hip that presented late or had failed conservative treatment with subsequent late OR versus CR, that were carried out during 1988 to 2003, by the lead surgeon were included. Dislocations secondary to neuromuscular causes or teratologic causes were excluded. Intraoperative arthrograms confirmed the concentric or eccentric reduction and determined subsequent intervention. The AP pelvis plain radiograph was used to measure the height of dislocation, as described by Tonnis, and monitor Acetabular index, and ossific nucleus width and height postreduction.

Results: After 134 OR's, 24 hips (19%, 95% CI: 16-23%) later required a pelvic osteotomy compared with 59 out of 104 hips (58%, 95% CI: 49-68%) in the CR cohort. There was no statistical difference in avascular necrosis rates between late OR (10.9%, 95% CI: 4.8-17%) and CR (11.4%, 95% CI: 5.8-17%). Acetabular index was a reliable predictor for the need of subsequent PO becoming significantly different in those that did (PO group) and did not (non-PO group) require further surgery approximately 1.5 years postreduction. There was no difference in the ON development after reduction in both PO and non-PO groups. The PO requirement was not affected by earlier failed Pavlik harness treatment but did change with ongoing surgical experience. Late OR produced the lowest secondary procedure rate without an increase in the incidence of avascular necrosis. There is a learning curve to this procedure that will affect these outcomes.

Level of evidence: Level III (Case-control study).