Abstract
Background : Improved treatment of spinal deformities is increasingly dependent on better fixation. Significant postoperative complications often occur following thoracolumbar fixation, particularly in long-segment constructs, and include loss of fixation, lumbar lordosis, and pseudarthrosis. We reduced a complication associated with a posterior implant by using a pedicle screw and claw hook.
Method : A validated 3-dimensional, non-linear finite element model of an intact L1-S1 segment was modified to simulate posterior fusion with instrumentation with a pedicle screw and/or claw hook. The posterior instrumentation represented a simulation of the conditions present immediately after surgery.
Results : Segment motion decreased with the addition of the claw hook during all motion. The pull-out strength of the pedicle screw with the addition of the claw hook was reduced in flexion. Maximum stress on the rod was increased by addition of the claw hook.
Conclusion : A reasonable combination of pedicle screw and/or claw hook fixation may be logical for reducing the incidence of pullout and for maintenance of spinal alignment. The biggest concern with the use of claw hook fixation is that extra fusion is necessary, and that instrument failure might occur.
