Abstract:

BACKGROUND: Adjacent segmental degeneration following cervical anterior fusion has become a focus. Semielastic internal fixation system exhibits less influences on adjacent intervertebral disc degeneration compared with commonly used rigid internal fixation systems.
OBJECTIVE: Regardless of the intensity of brace, to investigate the effect of cervical bioabsorbable cage or plate systems on intervertebral disc adjacent to operative segments, by pressure monitoring on intervertebral disc adjacent to operative segments.
METHODS: A total of 23 dogs of medical fitness were selected, and divided into 3 groups, including 5 in preliminary group (reference value of cervical intervertebral disc was measured), 9 in bioabsorbable cage group treated with bioabsorbable cage devices, and 9 in plate group treated with plate systems. All dogs underwent anterior discectomy on C _3/4, and were implanted with corresponding internal fixators. The pressure of intervertebral disc adjacent to operative segment (C _4/5 ) was measured in the operation. The pressure change from preoperative to postoperative was calculated as the intensity of brace. The animals were sacrificed at 6 months. Pearce grading and histological observation was performed to evaluate upper intervertebral disc degeneration.
RESULTS AND CONCLUSION: There were no significant differences between bioabsorbable cage and plate groups in pressure change of intervertebral disc adjacent to operative segments (P > 0.05). Spearman analysis showed that pressure differences in group was positively correlated with Pearce grading, histological grading 6 months following implantation (r=3.13, 2.78, P < 0.05). The intervertebral disc degeneration Pearce grading and histological grading were less in bioabsorbable cage compared with plate system group (P < 0.05). Results show that exorbitant brace pressure can induce the degeneration on dog’s intervertebral disc adjacent to operative segments, and the degeneration was decreased using bioabsorbable cage devices compared with plate systems.