COMPARATIVE STUDY BETWEEN PEDICULAR SCREWS, INTERBODY FUSION CAGES AND COMBINED PROCEDURES IN MANAGEMENT OF SPONDYLOLISTHESIS

Abstract

Spondylolisthesis is the anterior subluxation of one veiiebral body onto another. Because there is a failure of the compensatory mechanisms to maintain an adequate posteriorly directed force vector, the shear forces that exist in the intervertebral disc space cause anterior vertebral body slippage. Spondylolisthesis is a condition characterized by a failure of the three-column support with severe complex instability requiring reconstruction of the altered supporting structures.

The indications for lumbar fusion in the treatment of spondylolisthesis remain controversial. Pedicle screw/plate or rod fixation-type fusion procedures have became the standard for arthrodesis, yet interbody fusion offers several advantages; restoration •of load-bearing capacity to the ventral spinal column and maintenance of disc height which indirectly opens decompresses the neural foramina. The more extensile exposure required for intertransverse fusion procedures is obviated and less bone graft material is required, thereby minimizing donor-site morbidity. Threaded fusion cages (TFCs) provide a very different and much simpler concept based on both preferred principles of an interbody fusion and soft graft containment. A much smaller quantity of graft material is placed in the motion center of the disc with the recipient vertebral bone bed essentially surrounding the graft; providing it with a consistent vascular nutrition. Cages provide an excellent protective and supportive environment for such materials as the fusion rapidly develops. The TFCs have made the PLIF procedure faster, safer and less expensive, with more effective fusion and lower morbidity. The clinical results correlate well with other series, in term of better outcome of bone fusion, reduction potential, loss of correction, hardware failure and excellent related results.