Abstract
Purpose of the study
To report the difference in the rates of avascular necrosis (AVN) of the femoral head following change in the hip abduction angle in the hip spica.
Methods
Up until 2002, following closed and medial open reduction of the dislocated hip, the joint was immobilised in a 90° of flexion, 60° of abduction and 10-20° of internal rotation hip spica. The practice was changed after 2002 to 45° of hip abduction in the spica with other parameters remaining same.
We audited the rates of radiologic AVN in these two groups of children. Group A, before 2002, had 20 children and in group B, after 2002 till Aug 2007, had 53 children. AVN was quantified on 2 year radiograph by the classification described by Salter and noted its progression on serial radiographs.
Results
Twelve children (60%) in group A had radiographic evidence of AVN in the first two years after the procedure compared to 26 children (49%) in group B. This was usually in the form of delayed appearance of the ossific nucleus and delayed development of already appeared nucleus compared to other side. However, on serial radiographs when these patients were followed, at their latest follow-up, the femoral have developed symmetrically in all but 4 patients (20%) in Group A and 6 patients (11.3%) in Group B.
Conclusion
Children treated in hip spica after closed or medial open procedure developed transient avascular changes in their femoral head which recovered in most patients. This transient ischemia is further reduced by decreasing the amount of hip abduction angle without compromising the hip reduction achieved.
