Abstract
Background: Anterior scoliosis correctional surgery can result in screw pull out or pedicular fracture. This is more common in stiff curves where the instrumentation extends to the smaller, higher, thoracic levels. The fracture/intra-operative pull out usually occurs during the reduction maneuver. In all of our cases the curve was reduced in the standard cranial to caudal direction using a cantilever maneuver. We describe a salvage technique using circlage wires that can be used for this problem. We present seven cases and the final outcome.
Methods: The technique involves placing a longer screw into the damaged vertebrae so it protrudes 5mm proud. A 1.25mm circlage wire is then cut to length and passed around the tip of the screw. It is then looped in a figure of eight passed under the rod and tightened around the respective pedicle screw head. A case record and x- ray review of seven procedures performed was then carried out. The age of the patients was between 14 and 41 years (mean 20) at surgery. The pre-operative Cobb was between 72 and 43 (mean 58). One curve was flexible with a flexibility index of 70% but the remainder was stiffer (range 34%–40%). There was one thoracolumbar curve with a T11 fracture. All other curves were thoracic and the fracture levels were T5, T7, T7, T6+7, T6+7+8, and T6+7+8 respectively. Four out of seven were braced post operatively for three months. The Cobb angle over the instrumented levels immediately post surgery and at final follow up was measured. The technique was deemed to be successful if no significant loss of correction occurred.
Results: The technique held position in six out of seven of the subjects. The average loss of position in these patients was two degrees (range 0–4). In one subject the curve went from 28 degrees immediately post operatively to 38 degrees over 2 years. The four month post operative x ray showed no loss of position suggesting that this loss of position may not be due to the fracture. This patient remained pleased with his cosmetic result and went from 72 degrees pre operatively to 38 degrees at 2 year follow up.
Conclusion: Care should be taken in patients with stiff proximal curves. The use of larger 8mm screws may decrease pull out and consideration may be given to caudal to cranial reduction in some cases. Circlage wire rescue is a useful salvage procedure for inter-operative fracture or screw pull out during anterior scoliosis correction.
The abstracts were prepared by Mr Colin E. Bruce. Correspondence should be addressed to Colin E. Bruce, Consultant Orthopaedic Surgeon, Alder Hey Children’s Hospital, Eaton Road, Liverpool, L12 2AP.
