RECONSTRUCTION FOR VERTEBRAL BODY RESECTION USING TITANIUM MESH CAGES IN THE THORACOLUMBAR SPINE

Abstract

Introduction: Large anterior column defects of the thoracolumbar spine, after fracture decompression, tumour or other pathological resection, or spinal osteotomy present significant difficulties in respect to autograft procurement, donor site morbidity, graft instability and residual spinal instability. Titanium Mesh Cages for reconstruction thoracolumbar vertebral body defects (after corpectomy) offer an alternative to structural iliac crest autograft or allograft. The use of TMCs for inter-body reconstruction has been addressed yet the use of larger cages for corpectomy reconstruction has not. This study examines implant stability and deformity correction of TMCs following corpectomy reconstruction in the thoracolumbar spine.

Methods: Independent radiological review before, after and at follow-up (one year) was performed for 27 patients having implantation of TMCs. Measurement of thoracolumbar kyphosis was performed before surgery, immediately post operatively, and at one year follow-up. Correction of kyphosis was expressed both as angular improvement and percentage improvement. Cage settling into adjacent vertebral bodies, translational deformities and any evidence of implant failure was sought.

Results: Indications for reconstruction with TMC included burst fracture (13), post traumatic kyphosis (8), primary tumour resection (3), debridement of infection (1), and stabilisation of severe kyphotic deformity in achodroplasia with associated spinal stenosis requiring decompression (2). Desired resection and decompression was achieved as indicated. Correction of kyphosis was a mean of 12 deg / 61% (range 0 – 38 deg, 0–85%). No cage moved. One patient had kyphosis recurrence of > 5 deg (12 deg). Five patients demonstrated some settling of the cage within adjacent vertebral bodies (1–8%, mean 3.4% of height loss over construct length – the vertebral body above to the body below). Translational malposition of three cages occurred. One of these cases demonstrated the maximum settling and another was associated with the only case of instrumentation failure. Clinically significant spinal canal intrusion did not occur. One cage demonstrated buckling of the wall without evidence of other problem and the clinical result was excellent.

Discussion: Use of TMCs is safe when managing vertebral body reconstruction. Significant kyphosis or translational deformity has not occurred, however minor cage settling within adjacent vertebra may occur. Fusion rate is unknown as the cage mesh obscures graft maturation. Construct failure has only occurred after pre operative translational malalignment could not be corrected. This demanding procedure offers a reconstructive option with superior structural stability and reduced bone grafting morbidity.