Objective To evaluate the effect of polymethylmethacrylate (PMMA) augmentation on cervical stabil ity after anterior cervical interbody fusion (ACIF) before and after fatigue. Methods Twelve porcine cervical spines (C3-7) were subjected to testing angular displacement parameters, including the range of motion (ROM), neutral zone (NZ), and elastic zone (EZ), in nondestructive flexion and extension, right/left lateral bending, and left/right rotation on Motion Analysis motion capture system and MTS-858 servo-hydraul ic testing machine. Intact cervical spines served as control group (group A); oneleveldiscectomy and fusion was performed with anterior plate fixation based on group A as group B; flexion and extension,left/right lateral bending (5 000 cycles) fatigue testing based on group B as group C; the augmentation screw channel was used based on group C as group D; and flexion and extension, left/right lateral bending fatigue testing were performed based on group D as group E. Results The ROM, NZ, and EZ in group A were significantly different from those in other groups (P lt; 0.05) at flexion/extension, left/right bending, and left/right rotation. The ROM, NZ, and EZ in group B were significantly smaller than those in group C (P lt; 0.05) in flexion/extension, left/right bending, and left/right rotation, but there was no significant difference when compared with group D (P gt; 0.05). The ROM and NZ in flexion/extension and the EZ in flexion in group B were significant smaller than those in group E (P lt; 0.05), but there was no significant difference in the other indexes (P gt; 0.05). The ROM, NZ, and EZ in group C in flexion and extension, left/right lateral bending, and left/right rotation were significantly higher than those in groups D and E (P lt; 0.05). The ROM and NZ in flexion and extension and left/right lateral bending, and the ROM in left/right rotation, and the EZ in flexion and extension, right bending, and left/right rotation in group D were significantly smaller than those in group E (P lt; 0.05), but there was no significant difference in the other indexes (P gt; 0.05). Conclusion PMMA augmentation can significantly increase the instant cervical stabil ity and provide a biomechanics basis in cervical anterior plate fixation.
Objective To study the clinical application ofheterogenous bone graft combined with auto-marrow. Methods Deproteinated and degreased heterogenouscancellous bone combined with auto-marrow was used in 21 cases of anterior cervical interbody fusion. Among them, 2 cases were treated by bone graft only, and the other 19 cases were further treated by anterior plate fixation. Results The follow-up time was 12-36 months with an average of 21 months. After operation, posteroanterior and lateral radiograph of all the cases revealed that the reduction and the position of the grafting bone were good without inflammation or other complications. After 6 months of operation, the radiograph of 2 cases of cervical disk herniation, which were treated by bone graft only, showed the bones lost their height and the curve of the cervical spine returned to the state of preoperation. For the other cases, the grafting bonesremained their original figure without dislocation of the bone or fracture of the plate or the screw. The nervous function recovered variously. Before operation, 10 cases were ranked as grade A,7 cases grade C, 4 cases grade D according to Frankel classification. After operation, in grade A cases, 5 cases did not recover, 3 cases recovered to grade B, 2 cases to grade C; in grade C cases, 5 to grade D, 2 to grade E; all ofgrade D 4 cases to grade E. Conclusion Heterogenous bone combined with auto-marrow can be used as grafting material in the anterior cervical interbodyfusion, but its mechanical rigidity need to be improved or the fusion shouldbe aided with rigid internal fixation.