Anterior vertebral body replacement with a titanium implant of adjustable height: a prospective clinical study

Abstract

In the operative treatment of spinal injuries, the reconstruction of the anterior column of the thoracolumbar spine is still controversial. We conducted a prospective clinical study to investigate the clinical and radiological outcome of 50 patients treated with a vertebral body replacement of adjustable height (Synex). Fifty consecutive patients were evaluated during in-patient treatment and at 12 and 20 months post-operatively in clinical notes and radiographs. 38/50 patients were operated for traumatic fractures. Out of 50 patients 45 attended the follow-up clinic 1 year post-operatively and 39 of these patients were examined after 20 months. Twenty-five patients returned to pre-injury activities within 1 year. This number increased to 29/39 patients at 20 months. Seventy-three percent of the patients returned to their job. After 1 year 25/45 patients complained of little or no back pain and 6 months later six patients were limited in their back function. At 1 year only three patients complained of surgical site pain which was improved at their final follow-up at 20 months. Individual satisfaction was determined using a score on a visual analog scale containing 19 questions on back pain, and functional limitation of the spine that has to be filled in by the patients at three different points of time. The score decreased from 87/100 pre-operatively to 65/100 at 1 year follow-up (P<0.001). The average permanent correction of the injured vertebra was 16.8 degrees (88%) including 2.3 degrees (12%) loss of correction at 12 months after operation. Bony integration was obtained in 83%. Early and intermediate outcome with the Synex vertebral replacement device for reconstruction of the anterior column appears promising. The loss of correction or reduction was only minimal. On the basis of our results we recommend the Synex implant as an alternative for the fixation and stabilisation of thoracolumbar fractures. However, long-term results and a clinically random control study are still required.

Fig. 1

Synex™ expanded with distraction forceps (Stratec medical, Oberdorf, Switzerland)

Fig. 2

Localisation of spinal injuries

Fig. 3

Classification (n=38)

Fig. 4

“Subsidence” of the Synex™ in osteoporotic bone (62-year-old-male patient, L1 fracture, A 3.3.3.): a post-operative (image intensifier): Synex™ in the correct position (b). X-ray pictures following mobilisation: subsidence of Synex™

Fig. 5

Segmental kyphosis angle at different points in time (values in degree, minus kyphosis, plus lordosis): a thoracolumbar junction, b thoracic spine, c lumbar spine

Fig. 6

Twenty-three-year-old male patient with L2 fracture (A 3.2.1.) with incomplete paraplegia (Frankel C): bisegmental instrumentation L1-3 with the USS™ internal fixator, monosegmental anterior fusion with the Synex™ a. accident, b post-operative, c after implant removal, d CT after implant removal (14 months after accident): bony integration of the Synex™

Fig. 7

Nineteen-year-old female patient with L2 rotational burst fracture and incomplete paraplegia (Frankel D): a accident, b post-operative, c CT accident, d 12 months post-operative, e 1 month after implant removal