| Objective To study the clinical value of interbody cage systems in the surgical treatment of unstable lumbar segment, and evaluate the biomechanical properties.Method 1) Clinical appplication: 97 cases were selected for operation by posterior lumbar interbody fusion with BAK-cage or TFC device. 18 cases were diagnosised as lumbar disc degeneration disease(DDD),37 cases as lumbar stenosis, 23 cases as spondylolisthesis, 19 cases as unstable traumatic lesions. Of these,36 cases were received additional posterior pedicle devices; 13 cases with severe mechanical back pain were performed anterior interbody fusion with BAK-cage or TFC or interbody spacer,among them, 4 case underwent posterior previously and with poor result; A new anterior Mesh-cage was used in spinal reconstruction, this included 8 patients with thoracolumbar tumor, 2 patients with lumbar burst fracture,1 patient with osteoporotic late collapse of a vertebral body. 2) Biomechanical experience: 8 human cadaveric spinal speciments were divided into five groups: intact FSU, unstable FSU, FSU with posterior cages, FSU with RF pedicle system, FSU with cages and RF system. Mechanical stabilities were determined by testing in diffrent groups.Maxium valum of axial torque were measured by static eccntric loading test on the instrumented spines at last;Another 8 fresh frozen human cadaveric spinal speciments (Tn-L3) were used in this biomechanical test, the testing constructs used were: Li vertebrectomy and Ti2-Li> L^2 discectomy, bone-graft with anterior Kaneda device,mesh-cage interbody fusion device, mesh-cage with Kaneda fixation, mesh-cage with posterior pedicle screw system TSRH.Result 1.Clinical result: follow-up for average 21 months, 63 patients were available for review. Clinical result was excellent and good in 91.2% of cases underwent posterior interbody cage fusion, the preoperative percentage of slip were corrected in 89% of patients with spondylolithesis and in 100%patients traumatic dislocation. The satisfactory rate was 94.6% in the patients with severe back pain underwent anterior interbody cage fusion. The rate of union in the grafted area was 95% at the 6th month of postoperation. A preliminary experience showed that clinical effect was obvious as Mesh-cage used in the patients with tumor, symtoms were relieved and motion ability was greatly improved in these patients. 2. Biomechanical result: In the posterior experience, cages used alone significantly decreased the ROM in flexion,extention and lateral bending(p<0.05), minimally decreased in rotation(p>0.05); cages used with RF decreased the ROM greatly in all directions(pO.Ol). The mean maxial torque was 130N in cages alone,and it was 42 5N in cages combined with RF instrument. In the anterior experience, titanium mesh cage decreased segmental motions of the unstable spine. There was significantly less flexion,lateral bending and extention motion than in the intact group(p<0.05), whereas, axial rotationmotion was similar to that of the intact spine.Mesh-cage combined with anterior or posteriorfixtion improved greatly the segmental stability, there were siginificantly less motion in all directions than in the intact spine(p<0.01).Conclusion: The interbody cage implant produces immediate stabilisation on unstable spinal segment and offers a conductive biomechanical enviroonment for interbody graft healing by distraction properties and weight bearing function, restore the normal interbody space and spinal column lordosis, correlated with satisfacty clinical effect on some disease such as DDD, traumatic leision ,osteoporotic late collapse of a vertebral body and spinal tumors. |
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