AVASCULAR NECROSIS OF THE FEMORAL HEAD IN OLDER CHILDREN – IS JOINT DISTRACTION BY ILIZAROV-FIXATOR A VALID THERAPY?

Abstract

Introduction: Previous investigation showed that joint distraction (arthrodiastasis) is able to reduce intraarticular pressure and to have a positive effect on the regeneration of bone and cartilage on both sides of the joint. Many reports have been published about the results of arthrodiastasis in the treatment of femoral head necrosis in young children, pointing out good reconfiguration of the femoral head and improved range of motion. In contrast to that, -to our knowledge- there is so far no study showing the effect of hip joint distraction in older children with femoral head avascular necrosis.

Question: In the present study the outcome of the treatment of femoral head avascular necrosis in older children by hip joint distraction was investigated.

Methods: The hip joint distraction method was performed in three patients with necrosis of the femoral head. The causes of avascular necrosis were: Late onset Perthes’ disease in two patients and slipped capital femoral epiphysis (ECF) in one patient. The average age of the patients was 13.4 years. They all suffered from persistent severe pain and mostly limited range of motion of the hip joint. The plain radiographs revealed a Catterall IV, Herring C stade in both patients with late onset Perthes’disease. In the radiograph of the ECF patient a severe deformity of the femoral head was visible. After intraoperative soft tissue release, joint distraction was performed with an Ilizarov-ring fixation and immediately distracted 4–5 mm under image control. Distraction was continued 1 mm per day until the Shenton line was overcorrected. At this time the fixator was changed so that flexion-extension exercises were encouraged with the fixator in place. The patients were kept non-weight bearing. After 4 weeks the fixator was changed, so that in addition abduction up to 30° was possible. In total fixator duration time was 3.5 months. (In one case due to a fracture, the fixator was left for further 3 months) During distraction period with the fixator two patients suffered a femoral fracture without a causal adequate trauma.

Due to these major complications further investigations on additional patients have been stopped.

Results: The outcomes after 2.5 years showed in two patients an ankylosis of the hip joint with adductionflexion contracture and radiographical no reshaping of the femoral head. The third patient had a poor range of motion while radiographic findings showed a good reconfiguration of the femoral head. Nevertheless even in this patient advanced arthrosis was evident.

Conclusion: In conclusion, due to the major complications and the unsatisfactory “middle-term”-results, arthrodiastasis as a therapy of avascular necrosis of the femoral head in older children has failed in our study. In our opinion fracture was as a result of immobilisation osteopenie.