Magnetic resonance imaging evaluation of the spinal canal following arthrodesis and removal of sublaminar wires.

Seven patients who underwent posterior spinal fusion with Harrington instrumentation and sublaminar wires, and subsequently had these implants removed, were evaluated for evidence of spinal canal compromise with magnetic resonance imaging (MRI) at the sites of the sublaminar wires. All fusions were solid. The sites of 33 wires (27 levels) were evaluated with MRI. The average time the wires were in the spinal canal was 24.6 months. The average time following wire removal at the time of MRI was 61.7 months. Twenty-eight of 33 (85%) wire sites had no evidence of spinal canal compromise. Five sites had minimal (less than 15%) spinal canal compromise. The permanent structural changes in the spinal canal attributable to sublaminar wires appears to be quite modest.