Analysis of the primary and compensatory curvatures following Zielke instrumentation for idiopathic scoliosis.

The behavior of the primary and compensatory curvatures of 34 patients (follow-up, 24-48 months) with solid fusions following Zielke instrumentation were evaluated. All patients showed correction of their primary curvatures (range, 40-112%; average, 70%) postoperatively. Thirty-one showed loss of correction (range, 2.8-78.5%; mean, 25%). There was a higher tendency to lose correction if the curve was fused short of the Cobb measurement (35% vs. 17%). The majority of both the thoracic and the lumbosacral compensatory curves improved postoperatively (average of 38.6 and 66%, respectively). However, when the instrumentation was carried cephalad to the primary curve, there was a high probability that the upper compensatory curve would be worse after the surgery. Trunk list tended to improve during the course of follow-up.