[A new technique of osteotomy for femoral varisation in the management of hip dislocation and paralytic subluxation of the hip].

PURPOSE OF THE STUDY

Severe valgus deformity of the upper femur is a frequent feature of the unstable paralytic hip. Thus, the insertion of the osteosynthesis material during a varization osteotomy can be technical demanding. Risks and benefits of a modified femoral varization osteotomy were evaluated in a retrospective follow-up study.

MATERIAL

53 paralytic hips (33 patients) have been operated from September 1989 to april 1993. Mean age at surgery was 6 years. The etiologies were Spinal Amyotrophy in 12 hips, Cerebral Palsy in 31 hips and miscellaneous neurologic diseases in 10 hips. The average neck-shaft angle before surgery was 162 degrees. The mean Reimers' Index was 58 per cent.

METHODS

The upper femoral shaft was exposed by subperiosteal dissection in a circumferential manner. An intertrochanteric osteotomy was carried out. The direction of the femoral neck was identified. An AO 100 degree blade plate was then introduced under direct visual control through the cancellous osteotomy surface of the proximal fragment. Radiological and clinical outcome were assessed at last follow-up. Mean follow-up was 16 months.

RESULTS

Solid fusion was obtained in all patients. The mean postoperative neck-shaft angle was 104 degrees. The mean Reimers' Index was 17 per cent at last follow-up. Two infections were noted. Voluminous calcifications under the femoral neck have been observed in 6 cases. Recurrence of the valgus deformity was noted in 9 hips at last follow-up.

DISCUSSION

This simplified varization technique permits a large amount of varization. The medialization diminishes the problem of protruding hardware. The complications rate appears to be low without any femoral head necrosis in this series despite subperiosteal dissection of the femoral neck.

CONCLUSION

The authors think that this modified varization technique may deserve consideration in the treatment of the unstable paralytic hip.