ILIZAROV HIP RECONSTRUCTION FOR THE LATE SEQUELAE OF INFANTILE HIP INFECTION

Abstract

Background: The late sequelae of infantile hip infection include absence of the femoral head and neck, proximal migration of the femur, lower-extremity length discrepancy, abnormal gait, and pain. The Ilizarov hip reconstruction includes an acute valgus and extension osteotomy at the proximal part of the femur combined with gradual distraction for realignment and lengthening at a second, more distal, femoral osteotomy. The purpose of this study was to determine whether this technique can successfully treat the sequelae of infantile hip infection. Methods: We performed a retrospective review of a series of eight consecutive patients with a Type-IV or V hip deformity, according to the classification system of Hunka et al., after an infantile hip infection. The patients' mean age at surgery was 11.2 years. All hips were unstable, with a mean of 3.8 cm of proximal migration. A mean valgus angulation of 44° and a mean extension angulation of 19° were created with the proximal osteotomies. Distal femoral lengthening averaged 5.7 cm, and distal femoral varus angular correction averaged 10°. The mean time in the Ilizarov frame was 4.7 months. Outcomes were evaluated clinically and radiographically. The clinical evaluation included gait analysis and the use of a modified Harris hip score. Results: At the time of follow-up, at a mean of five years, the mean lower-extremity length discrepancy had improved from 4.6 cm preoperatively to 0.7 cm. The mean modified Harris hip score had improved from 51 points to 73 points (p = 0.007). All extremities were well aligned, with a mean pelvic mechanical axis angle of 89°. The mean deviation of the mechanical axis was 2 mm in a lateral direction. The mean stance-time asymmetry improved from 16% to 5.4% (p = 0.0037), and the mean ground-reaction force (second peak) improved from 102% of body weight to 122% of body weight (p = 0.0005). Conclusions: The Ilizarov hip reconstruction can successfully correct a Trendelenburg gait and simultaneously restore knee alignment and correct lower-extremity length discrepancy. When the procedure is performed on a young patient, remodeling of the proximal osteotomy site and development of lower-extremity length discrepancy should be expected and the procedure may need to be repeated. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.