PAPER 187: THE ROLE OF THE AO EXTERNAL FIXATOR IN SUPRACONDYLAR FEMORAL OSTEOTOMIES IN CHILDREN

Abstract

Purpose: Femoral torsion is traditionally treated by a proximal osteotomy. At this level, a significant exposure is required. Furthermore, internal fixation is typically removed by additional surgery at twelve months. We propose to demonstrate the efficacy of the AO external fixator to maintain osteotomies in the distal femur for torsional correction.

Method: Between September 1994 and April 2001, supracondylar osteotomies were performed on 38 femora in 21 children with torsional and angular deformities. The average age at presentation was 10 years. Twenty-three femora had excessive anteversion and 15, retroversion. The technique required the lateral placement of three 4.0 mm end-threaded Schanz pins parallel to the distal growth plate. Three similar pins were inserted more proximally in line with the femoral shaft. A transverse osteotomy was performed through a limited lateral approach. After correction of the deformities, each pin was linked to all others by clamps and carbon fiber rods.

Results: Lower extremity alignment was restored in all patients. Genu valgum was addressed in eighteen osteotomies. Five extension osteotomies were performed for fixed knee flexion deformities. The external fixators were removed at an average of ten weeks. One child had a superficial pin tract infection requiring intravenous antibiotics. All osteotomies united without complications. No postoperative femur fractures occurred.

Conclusion: Osteotomy at the distal femur has the advantage of correcting both torsional and angular deformities. The exposure required is limited. The AO external fixator provides precise control of the osteotomy and allows for subsequent adjustability. This method effectively controls supracondylar osteotomies and avoids a second procedure for hardware removal.