Anterior cervical fusion with a bio-resorbable composite cage (beta TCP–PLLA): clinical and radiological results from a prospective study on 20 patients

Abstract

A resorbable composite material (40% PLLA and 60% beta TCP) with a high breaking strength and capacity to withstand plastic and elastic strain has been developed for cervical interbody fusion. This is a prospective study to evaluate clinical and radiological results of 20 patients implanted with 27 cages (mean follow-up, 27 months). Clinical (neck disability index, VAS, neurological evaluation) and radiological (anteroposterior, lateral, bending X-rays) data were assessed before and after surgery. At the end of the study, CT scan was performed to evaluate fusion, resorption of the cage and density of the new tissue substituting the cage. The mean patient age was 50.3 years (range, 18-79 years). The average improvement was 55% for neck pain, 83% for arm pain and 65% for NDI, with 85% good or excellent results at final outcomes. Radiologically, lordosis was significantly improved (mean gain of 5.4 degrees and 3.7 degrees for overall and segmental lordosis, respectively). This correction was conserved in 95% of cases. Fusion was obtained in 96% (CT evaluation). Resorption was started in all cases and completed in an average of 36 months after surgery. The mean density of tissue substituting the cage was 659 UH with a range, of 455-911 UH (compatible with bone nature). Over time, the amount of bony tissue increased and the graft remodelled with an increase in density value. This demonstrates a biological activity and changing bone mineral content of this tissue. The new composite cage under investigation provides long-term fusion without loss of correction or inflammatory reaction. The ceramic block guarantees the maintenance of the disc height and its slow resorption allows long-term fusion and stability with good and reliable clinical and radiological outcomes.