Screw position after double-rod anterior spinal fusion in idiopathic scoliosis: an evaluation using computerized tomography.

Study Design: A retrospective evaluation of screw position after double-rod anterior spinal fusion in idiopathic scoliosis using computerized tomography (CT).

Objective: To evaluate screw position and complications related to screw position after double-rod anterior instrumentation in idiopathic scoliosis.

Summary Of Background Data: Anterior instrumentation and fusion in idiopathic scoliosis is gaining widespread use. However, no studies have been published regarding the accuracy of screw placement and screw-related complications in double-rod and double-screw anterior spinal fusion and instrumentation in idiopathic thoracolumbar scoliosis surgery.

Methods: CT examinations were performed after surgery in 17 patients with idiopathic scoliosis. At each instrumented level, the position of the screw and the plate relative to the spinal canal, relative to the neural foramen, and relative to the aorta was measured. Complications related to screw position were registered.

Results: A total of 189 screws in 17 patients were evaluated. Malposition occurred in 23% (16 patients) of the total number of screws. Three screws (2 patients) were partially in the spinal canal (1%). This resulted in pain in the right leg in 2 patients. However, electromyography showed no abnormalities. At three levels (3 patients), there was contact between the instrumentation and the aorta. However, no vascular complications occurred. A total of 113 screws (10 patients) were placed under fluoroscopic control and 76 screws (7 patients) were placed without use of fluoroscopy. Less screw malposition was observed in the group in which fluoroscopic control was used (19% vs. 30%, not significant).

Conclusions: Screw placement in double-rod anterior spinal fusion in idiopathic scoliosis seems to be technically demanding, and the use of fluoroscopic control results in less frequent malposition. The risk of neurologic and vascular complications is low.