EFFECT OF CORPECTOMY AND DISCECTOMY FUSION PROCEDURES ON THE STABILITY OF MULTI-LEVEL CERVICAL CONSTRUCT WITH ANTERIOR RIGID SCREW-PLATE FIXATION - A FINITE ELEMENT MODEL STUDY

摘要

Cervical fusion is a traditional surgical technique in the management of spondylotic pathologies. An increased rate of arthrodesis has been well stated in the literature by using anterior and/or posterior instrumentation. Despite excellent results for the multi-level cervical fusions, failures due to the pseudarthrosis, graft dislodgement, migration and screw loosening were reported. These failures were also found to be directly proportional to the number of fused levels. The multi-level fusions with a single strut graft (corpectomy) have only two graft-endplate interfaces and a lower rate of pseudarthrosis failures. But it has a longer lever arm and moment, thus disrupting the normal sagittal alignment of the cervical spine. On the other hand, the multi-level fusion with multiple inter-body grafts (discectomy) maintains the sagittal alignment, but a higher rate of pseudarthrosis failures were expected due to a large number of graft-endplate interfaces. Some investigators have advocated a combination of corpectomy and discectomy, while others believe to perform either one of them due to the individual advantages and disadvantages as per their patient needs. Consequently, a dilemma and controversy still exists in the selection of the type of reconstructive fusion technique. The objective of the present study was to compare the biomechanical stability of the three reconstructive fusion techniques - corpectomy, discectomy and combined corpectomy-discectomy. The stability of the superior motion segment was compared to the inferior motion segment to determine the direction of propagation of the adjacent segment disease.