Osteogenic potential of fibrous ring tissue in cervical intervertebral disc / 中国组织工程研究

ABSTRACT

BACKGROUND: Ossification of intervertebral disc, and ossification of spinal ligament and fibrous tissues are still uncertain.OBJECTIVE: To observe osteogenic potential of fibrous ring in the cervical intervertebral disc during bone fusion.DESIGN, TIME AND SETTING: The comparative observation was performed at the Experimental Animal Center of Second Military Medical University and Shanghai Institute of Orthopedics in October 2006.MATERIALS Ten healthy goats, including 6 males and 4 females; titanium alloy cervical hollow threaded columnar internal fixator (CHTF) for goat, simulated human used internal fixator by Kanghui Medical Innovation Co., Ltd., Changzhou.METHODS: Every goat underwent conventional anterior cervical decompression and internal fixation. Two adjacent intervertebral spaces among C2-6 were selected and implanted with 2 CHTFs for each space. Of the 4 CHTFs, 3 were filled with cancellous bone alone, cancellous bone plus fibrous ring, and fibrous ring alone, respectively; the other one filled with nothing served as blank control.MAIN OUTCOME MEASURES: Implant location and fusion condition on anteroposterior and lateral radiographs and CT plain scanning at 6 and 12 weeks postoperatively; bone graft fusion and regional tissue reaction by histology.RESULTS: Radiographs and CT showed that CHTF was in the position during the whole experimental procedure with no loosening, displacement or dislocation. At 6 weeks, bone tissue was found surrounding CHTF and the vertebral body, and bone bridge formed in the connection site of CHTF and the vertebral body. New cartilage and bone trabecula formation were found in the CHTF filled with cancellous bone alone, accompanied by necrotic original bone graft; in the CHTF filled with cancellous bone and fibrous ring, necrotic fibrous tissue and newly formed cartilage accumulation surrounding original bone trabecula and fibrous ring were found; 6 weeks after surgery, there were fibrocartilage in fibrous tissue of CHTF filled with fibrous ring alone, and at 12 weeks postoperatively, newly formed cartilage was observed. In blank control group, only few newly formed cartilages were found at 12 weeks postoperatively. CONCLUSION: Enchondral ossification of fibroblast may be the osteogenic pattern of fibrous ring of cervical intervertebral disc.