The Comparison of the Results Between AO Internal Fixator (Long lever-arm) and Screw-Rod System (Short lever-arm) Through Posterior Approach in Unstable Thoracolumbar Fractures / 대한척추외과학회지

STUDY DESIGN: Prospective study. OBJECTIVES: To analyze the outcome of posterior reduction and fixation with the AO internal fixator and with the screw-rod system in unstable thoracolumbar fractures and to investigate differences in effectiveness between the two methods. SUMMARY OF LITERATURE REVIEW: In unstable thoracolumbar fractures, fixation with the AO internal fixator is an effective method for posterior reduction. However, the results of correction are quite variable. MATERIALS AND METHODS: We analyzed 51 patients with unstable thoracolumbar fractures who underwent correction through posterior approach between 1997 and 2003. We divided the patients into two groups: Patients in Group A (25 cases) were treated with the AO internal fixator, and patients in Group B (26 cases) were treated with the screw-rod system. We added transpedicular bone grafts for 17 patients in Group A. We evaluated correction of deformity (anterior and posterior height of vertebral body, sagittal index, disc height), loss of correction, spinal canal clearance, and neurological recovery. RESULTS: Comparing correction of deformity, we saw better results in Group A than in Group B in regards to sagittal index and anterior height of vertebral body. However, we saw a higher degree of correction loss in the anterior height of the vertebral body in Group A. We grafted autogenous bone into the fracture site by transpedicular approach for 17 patients in Group A. We saw less correction loss in the anterior vertebral body height and sagittal index. In regard to spinal canal clearance, we saw better results in Group A (18%) than in Group B (10%). As for neurological recovery, we could not find any statistically significant difference between the two groups. CONCLUSIONS: Through an operative procedure, we could achieve better results in restoration of anterior vertebral height and canal clearance with the AO internal fixator system. Further study is necessary to keep the reduced state of vertebral height.

Surgical Treatment of Unstable Thoracolumbar Fractures with Posterior Approach / 대한정형외과학회잡지

PURPOSE: To analyze the results of posterior reduction with AO internal fixator or screw-rod system in thoracolumbar fracture and to find an adequate method of treatment. MATERIALS AND METHODS: We analyzed 40 cases of unstable thoracolumbar fractures who were operated with posterior approach without additional anterior approach. All cases were divided into two groups by the instrument used: Group A (25 cases) with AO internal fixator and Group B (15 cases) with screw-rod system. They were classified according to AO classification. RESULTS: There was no significant difference in correction and maintenance of sagittal index among types of AO classification except neurological recovery which was better in Type A. AO internal fixator had better results than screw-rod system in correction and maintenance of sagittal index, but no difference in neurological recovery. Eleven cases had more than 5 degrees of correction loss at final follow-up. In these cases, we found several findings; decreased vertebral body height, decreased disc height, bony collapse around screw at superior segment, metal loosening between rod and screw and metal breakage of screw. CONCLUSIONS: We concluded that AO internal fixator was good for the posterior reduction of thoracolumbar fracture in this study. But we think that continuous follow-up and further study are needed.

Operative Treatment of Thoracolumbar Spine Fractures with AO Internal Fixator / 대한정형외과학회잡지

A retrospective analysis of eighty-six consecutive patients who underwent stabilization with AO internal fixator for thoracolumbar spine fractures was performed at Wonju Christian hospital between 1988 and 1994. The purpose of this study was to determine the quality of reduction and stabilization with the fixateur interne(F-I) and the effects of limited posterior segmental fixation on neurologic recovery and rehabilitation. The mean wedge angle of the fractured vertebra was changed from 19.2° preoperatively to 8.4° preoperatively, and remained almost unchanged at last follow up(10.2°). Also, the wedge index showed nearly no bony loss of correction within the reduced fracture vertebra(corrected from 0.63 to 0.83 and 0.81 at follow up). The mean kyphosis angle was corrected from 22.3° to 8.3° and 16.9° at last follow up. Most of the change of kyphosis was due to the disc space collapse above the fractured vertebra. Transpedicular cancellous bone grafting for the vertebral body fractures effected a significant improvement in results of fixation. All cases of translational displacement were anatomically reduced. No neurologic or vascular complication occurred. Fixateur interne is capable of achieving three-demensional reduction in unstable thoracolumbar spinal fractures and maintaining sufficient stability until bony healing is achieved.

Operative Treatment of Thoracolumbar Spine Fractures with AO Internal Fixator / 대한정형외과학회잡지

The AO internal fixation system(the Fixateur Interne) is effective in reducing and stablizing a variety of unstable thoracolumbar fracture patterns. It is relatively effective in decompressing the canal of retropulsed bony fragments associated with burst fracture. Sixty-Two patients with unstable thoracolumbar spine fractures were treated with the AO internal fixator. They were followed for an average of 21 months(range 15-29 months). A compartive radiographic analysis of kyphosis and vertebral height was made using pre-operative, post-operative and follow-up radiogram. Changes in neural canal compromise were measured in 18 cases of burst fractures. Failure of instrumentation occured in 9 cases which were carefully analyzed. Recently, we've constructed the system of which the Schanz screws would be directed divergently in sagittal plane in the hope that the load to the screws might be reduced, thus the failure rate.