| Objetive: To evaluate the biomechanical stability of the cervical spine with the two-level anterior cervical discectomy , intervertabral graft and bone graft pulsing anterior plating in cadaveric cervical models.To compare the clinical and radiographic success of two-level discectomy and the effect of anterior cervical plate fixation.Methods: The cervical spines of 5 fresh cadaveric specimens from C2-T1 were obtained. The age at the time of death ranged from 21 to 67 years old. The average age is 42 years old. The specimens were dissected with preservation of osteoligamentous structures. The spines were double-bagged and frozen at -20C until the day of testing. The time of preservation is from 18 to b46 days with the average time of 30 days. All specimens were evaluated radio-graphically before testing, to exclude occult malignant disease and to assess relative bone quality. Using a polyester fixation medium, each specimen was embedded at C4 superiorly and C6 inferiorly in two-level instability. Each specimen was performed with transaction of anterior cogitudinal ligamentous and C4-5, C5-6 discectomy, preservation of posterior longitudinal ligamentous for injure model.Autogenous iliac crest bone graft was placed in the disc space with R-S method for bone graft model. After that, Orion anterior cervical locking plates were applied for the fixture model, 15-degreecephaled extending from the midbody of superior to the midbody of the inferior cervical vertebral bodies.Two lock screws with specimens were tested nondestructively in intact, two-level discectomy, pulsing bone graft, application of anterior cervical plates state in turn to assess the load-deformation of in superior-inferior(DSI), posterior-anterior(DPA) and left-right deriction(DLR). Each test was repeated for three cycles, consisting of a 10-sesond ramp per cycle.Thus, the third cycle used for analysis. In DSI, the specimens were subjected to 300N with a load speed of 10 mm/min. Both DPA and DLR were only subjected to 200N. The center of DSI test was matched to posterior annulus fibrosis of the C5 intervertebral disc. The loaded point for DPA, DLA was matched to the spinous facet and joint capsules of C5 respectively. The date obtained from all test were presented in the original scales as mean±standard deviation. One-way ANOVA was used for the comparison between groups. Statistical significance for the test was set at p<0.05.Clinical following: During two years old, 46 patients (aged at 36-69 years old, mean 46.6years old; 21 men, 27 women) including cervical spondylotic myelopathy 24 cases, cervical ossification of the posterior longitudinal ligament 10cases, prolapse of cervical disc 8 cases, instability of cervical spine 4 cases. All patients were followed up after operation for 6-24 months, average 15.7m. All disc material were removed with Cloward means. Of the 48 patients, 26 patients had cervical plates with 11 Orion and 17 CSLP. After surgery, all patients were treated with the same protocol consisting of immobilization with a hard cervical collar for 10 weeks. A radiograph was taken at 2 and 6 weeks after surgery, and then at monthly intervals until the fusion was judged to be solid of the presence of pseudarthorsis was identified. Clinical follow-up evaluations were performed by Odom's criteria.(Excellent-all preoperative symptoms relieved; abnormal findings improved, Good-Minimal persistence of preoperative symptoms; abnormal findings unchanged or improved, Fair-Definite relief of some preoperative symptoms; other symptoms unchanged or slightly improved, Poor-Symptoms and signs unchanged or exacerbated.)Results: ⑴Biomechanical result①Superior-inferior press stiffness (SSI): The SSI of the injure was significantly smaller than the intact (P<0.05), the one graft significantly larger than the intact.The application of anterior cervical plate significantly further increase SSI(P<0.05). ②Posterior-anterior shear stiffness (SPA): The SPA of the injure was significantly smaller the intact (P<0.05). The bone graft, cer... |
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