A prospective investigation of internal fixation of acute thoracic and lumbar spine fractures using pedicle screws and dynamic compression plates was performed. This article details the results of 23 patients who were followed for an average of 20 months. The indications for the procedure were an unstable fracture--dislocation below the eighth thoracic vertebra or low lumbar fractures that would be difficult to treat with conventional spinal implants. The patients were divided into three groups based on the fracture pattern and the level of the fracture. Group I consisted of fracture--dislocation injuries at the thoracic level and thoracolumbar junction. Group II patients sustained lumbar fracture--dislocations, and Group III contained lumbar burst fractures. Sagittal and coronal angles as well as anterior and posterior vertebral body height were measured at the injury level preoperatively, postoperatively, and at 3-month intervals. Statistical analysis of these angles demonstrated that Group I and III patients had significant correction of their relative kyphotic deformity after surgery; however, there were no differences in kyphotic angle at the 3-month interval. Despite this eventual return to preoperative angles, all patients except one developed solid fusion. There was no increase in neurologic deficit. One patient developed an asymptomatic pseudarthrosis demonstrated by breakage of both plates through unfilled screw holes at the motion segment. Other complications included one wound infection, one case of arachnoiditis after an intradural bone fragment was excised, and one dural tear created by a Kirschner wire, which did not result in a neurologic deficit or a cerebrospinal fluid leak.(ABSTRACT TRUNCATED AT 250 WORDS)