Biomechanical Stability Valuation And Clinical Research Of Autogenous Morselized Bone Graft Impaction In The Posterior Lumbar Interbody Fusion

BackgroundSenile lumbar degeneration including lumbar disc herniation combined with segmental unstable, lumbar spinal stenosis, degenerative lumbar instability, is a very common orthopedics disease in the old coursed chronic Low-back pain, lower extremity numbness, claudication intermittent, and so on. Lumber interbody fusion is the effective method, especially the posterior lumbar interbody fusion is familiar in clinical practice. The most important things that affected the pre-operation are the stabile fixation measure and sufficient and strong bone grafts. However, there is still some arguments about the source and shape of bone material, and the method of bone-grafting. There are some complications using traditional iliac crest bone graft, such as the bone displacement, collapse, chronic donor site pain. Allogeneic bone could be lost due to the allograft rejection. As the development of cage, the height lose of the interveterbral space is conspicuously decreased, but instead of cage sinking and expensive hospital fee.Autogenous morselized bone graft as the"Golden standard"of bone graft, is succeed in extremities operations combine with impaction technology, and not lack of report in lumbar interbody fusion. As a new method,Autogenous morselized bone graft impaction maybe have some advantages. This study is designed for providing biomechanical stability valuation and clinical evidence for the clinical use and promotion of autogenous morselized bone graft impaction in the posterior lumbar interbody fusion.Objectives1. The study made animal model building with pig spine. To evaluate and compare the biomechanical stability properties of autogenous morselized bone graft impaction with vertebral pedicle screw fixation, cage with vertebral pedicle screw fixation, so as to provide theoretical basis and experiment guidance in clinical use of autogenous morselized bone graft impaction with vertebral pedicle screw fixation in PLIF.2. To investigate the technique and clinical feasibility about the application of autogenous morselized bone graft impaction in the posterior lumbar interbody fusion for senile lumbar degeneration, and provides the clinical evidence for its use and promotion.Materials and Methods1. Chose 12 fresh adult pigs, separated the lumbarvertebrae involved 4 vertebrae segments (L1-L4). After took the posteroanterior and lateral radiograph, removing muscles tissue carefully with the ligament and disc reserved. Randomly divided these specimens into 2 groups: autogenous morselized bone graft impaction with vertebral pedicle screw fixation (experimental group), cage with vertebral pedicle screw fixation (control group).2. Resin embedding method and graded facetectomy and discectomy were made to model the types of Spinal Instability. Experimental group used autogenous morselized bone graft impaction with vertebral pedicle screw fixation; control group used cage with vertebral pedicle screw fixation. The 3-dimensional motion of specimens were tested in intacted state, instability state and fusion state, which the flexion, extension, bilateral bending and axial rotation loading were applied to the specimens and the range of motion(ROM) were determined by the 3-dimensional laser scanner. Analyzed the data with Spss 13.0 software.3. A retrospective study was carried out from 2007 October to 2008 December, and there were 21 senile lumbar degeneration cases (28 segment) who were operated by autogenous morselized bone graft impaction in the posterior lumbar interbody fusion in our department. There were 7 cases lumbar disc herniation combine with segmental unstable, 6 cases lumbar spinal stenosis, 8 cases degenerative lumbar instability. Before operation, in addition to anteroposterior, lateral, lateral dynamic radiographs and CT/MR were obtained in all patients, and the diagnosis were certainly. All the patients were treated with regular conservative treatments above for 2 months before surgery. All patients were followed up more than 12 months. The fusion rate and improvement of Segmental Lordosis, Lumbar Lordosis besides Relative Lumbar Space Height were evaluated according to the pre and post operative X-ray. The clinical outcomes were measured according to VAS scores, ODI scores as well as Macnab evaluation scale. Analyzed the data with Spss 13.0 software.Results1. There was no significant difference in all stability index(ROM and NZ)between two groups in intact state (P>0.05). Compare with intact state,there was significant difference in all stability index in instable state in both groups. After PLIF,there was no significant difference in all stability index between two group(P>0.05).2. All patients were followed up more than 12 months. The bone fusions were presented in 3~5 months postoperatively. In this series, no reduction and fixation failure was found. After operation, the lower back pain and leg pain were relieved in different level in all cases. There was 1 case which CT scanning showed that there were some morselized bone in the spinal canal the sixth day afteroperation, causing the nerve compressed, another case that the soft tissue of the cut was infected post-discharge the fifth day afteroperation. The preoperative, 1 month postoperative and latest follow-up ODI scores were 43.05±7.26, 20.36±5.36 and 10.06±5.31 separately (P<0.01),while the correspongding VAS scores were 8.17±2.12, 2.54±0.89 and 1.23±2.01 (P<0.01) . The clinical outcomes were determined using a Macnab criteria, which revealed that 10 patients had excellent result, 9 had good, 0 had fair, 2 had bad, the excellent and good rate 90.5%. Both the Lumbar Lordosis and Relative Lumbar Space Height are ameliorated and maintained efficiently,there were significant difference preoperative and 1 month postoperative (P<0.01), while no significant difference postperative and 1 month postoperative (P>0.05) in both index.Conclusion1. Both the autogenous morselized bone graft impaction with vertebral pedicle screw fixation and cage with vertebral pedicle screw fixation can improve the spine immediately biomechanical stability for Spinal Instability, and there is no statistical difference of spine stability capacity between two groups.2. There is a good short-term clinical outcome of pedicle screw fixation with autogenous morselized bone graft impaction applying in posterior lumbar interbody fusion for senile lumbar degeneration. The interbody fusion rate is high, the Lumbar Lordosis and Lumbar Space Height can be ameliorated and maintained efficiently,while the clinical complicational rate is low, which is deserved clinical research and promotion.