Follow-up Results of Z-plate Fixation in the Thoracolumbar Burst Fracture

흉요추 방출성 압박골절의 Z-plate를 이용한 고정술후 추적검사 결과

Objectives : Thoracolumbar burst fractures(TBLF) result in not only compressive deformity of vertebral body but also spinal cord compression by bony fragments. Many thoracolumbar burst fractures demand both anterior decompression and intervertebral fusion. Most of spinal surgeons use anterior instrumentation for anteior intervertebral bony fusion. The use of Z-plate has been increased recently, however there has been only a few reports regarding its clinical long-term strength. We studied nineteen patients with TBLF to find out the long-term stability of Z-plate. Methods : We have operated 19 patients from March 1996 to August 1998. They were treated with anterior decompression through either a transthoracic, retroperitoneal extrapleural or retroperitoneal approach. Retropulsed bony fragments were removed completely by corpectomy. Iliac bone graft was used for interbody fusion in all of the cases. They were evaluated by plain X-ray films including flexion and extention lateral films. Cobbs angle was used to evaluate kyphotic and lateral wedging deformity. Results : Burst fractured sites were T11 in two, three T12, nine L1, and five L2. Mean follow-up duration was fifteen months. Preoperative average kyphotic angle was 23.7 degree. Immediate postoperative kyphotic angle was 10.2 degree. Follow-up resluts of average kyphotic angles revealed 14 degrees. Four patients(21%), including two spinal 3-column injury, showed increasement of kyphotic angle more than 5 degree or breakage of intrumentation. Two patients showed the difference of kyphotic angle more than 3 degree. Five patients(26%) revealed lateral wedging deformity more than 3 degrees. Postoperative complications were two meralgia parestheticas, one pulmonary atelectasis and two donor site infections. Four of the eight patients, who initially showed incomplete spinal cord deficits, were nerologically improved by Frankel's grade. Conclusion : Z-plate fixation and iliac bone graft after anterior decompression in thoracolumbar burst fractures is a safe and easy method. Immediate postoperative results revealed excellent correction of posttraumatic kyphosis, but long-term follow-up evalution showed insufficient strength. Therefore we believe that use of Z-plate should be carefully decided, especially in the case of large lumbar fracture or 3-column injury.