Long-term results after posterior fixation of thoraco-lumbar burst fractures

Current concepts of treating thoraco-lumbar burst-compression injuries are based on posterior transpedicular fixation techniques which are angular stable. However, the long-term results of this approach are controversial due to inconsistent reports and due to a paucity of data on late outcome. In the present study we analyzed 50 patients retrospectively who had an unstable burst-compression injury at T 11-L 2 (type A 3 according to Magerl) without a neurological deficit. All fractures were stabilized by an internal fixator either with or without transpedicular spongiosa grafting. Patients were treated between 1991 and 1997. Follow-up times ranged from 36 to 103 months. Follow-up examinations collected occupational, subjective and clinical data (activity score, Hannover spine score) and included radiographic measurements. The latter were used to calculate the sagittal index (SI) which measures deformities of the fractured vertebral body, and the sagittal plane kyphosis (SPK) which additionally describes an eventual destruction of the affected intervertebral disc. Compared with the preinjury status, the percentage of subjects who were able to do physical labor was reduced by half at follow-up, and four times as many patients had a permanent disability. Correspondingly, activity scores and Hannover spine scores declined significantly. After the initial surgical correction SI remained stable until follow-up, whereas SPK decreased again towards pre-operative values indicating a progressive deformity of the intervertebral disc space. Clinical results did not correlate with radiographic results, and neither the time until follow-up nor the type of fracture n or the use of transpedicular bone grafting affected clinical or radiographic results significantly.