Outcome of Wisconsin instrumentation in idiopathic scoliosis. Minimum 5-year follow-up.

Wisconsin segmental spinal instrumentation was developed by Drummond et al to provide rigid fixation for correction of spinal deformities without the risk of neurologic injury associated with the passage of sublaminar wires. Up to this point, there have been no outcome studies with follow-up of longer than 2 years. Thirty-five patients with adolescent idiopathic scoliosis treated by the Wisconsin procedure between 1984 and 1987 were reviewed by radiographs, physical examination, and an outcome scale. Minimum length of follow-up was 5 years with an average of 6.3 years. Curves were corrected from a mean of 59 degrees preoperatively to 32 degrees postoperatively (46%), and 36 degrees at final follow-up (39%). Wisconsin segmental spinal instrumentation did not increase thoracic kyphosis. There was evidence of slight lumbar flattening in long fusions. According to the criteria described, 92% had a successful outcome. Complications of the procedure included two wound infections (one superficial, one deep), one rod displacement, and two wire breakages. No pseudarthroses or neurologic complications were identified in this series. Wisconsin segmental spinal instrumentation safely achieves the objectives of partial correction, arthrodesis, and early return to function. The technique may still have a role, particularly in the thoracic region, in selective thoracic fusion of King type II curves, rigid curves, and double thoracic curves.