| Part 1 :Biomechanical study of the two operation method in treating thoracolumbar burst fractureObjective: In recent years, with the development of architectural and transport , the incidence of thoracolumbar burst fracture has been increasing. there is still debate on choosing surgery approach to treat thoracolumbar burst fracture. For unstable thoracolumbar fractures, the advantages of adopting posterior surgery is small trauma and risk.The operation itself is simple, and the postoperative complication is relatively less, however, it cannot get direct decompression, the compression of spinal can not be removed thoroughly sometimes ,so the posterior approach need a second anteriorlateral surgery of spinal canal decompression. But the serious shortcoming lies in it restores vertebrae height only through mechanical reduction, which fails to provide direct graft bone to fuse the vertebrae, it has the risk bone nonunion and need reoperation .Using anterior and posterior approach, it can better solve the problems of anterior column support , remove spinal compression completely and posterior column fixation. But the operation itself makes great trauma, more bleeding and need long time, it also has high incidence of complications . For that reason, We adopted One- stage partial vertebrectomy,titanium mesh implantation , and pedicle screw fixation to restore spine in the treatment of thoracolumbar burst fractures through posterior approach. Using a surgical incision solved two problems that need two surgical approaches to treat. It reduced the surgical risk greatly, obtained better clinical effects. The aim of experiment was to compare the biomechanical characterises of the two surgical methods through thoracolumbar burst fracture model, to provide scientific theory basis for clinical treatment, especially in choosing surgery approach. Method: 8 the same kind of fresh calf thoracolumbar spine specimens(T12-L5)(Fig. 1)provided by Langfang Slaughterhouse.All the young calf weight 150 to 200 kg, less than six months. All the muscles around vertebral bodies were removed, except Supraspinous ligament, interspinous ligament, anterior longitudinal ligament and posterior longitudinal ligament. Small joints and vertebral were intact during the process. Specimens were preserved in fridge at– 20℃after sealed by double plastic bag and taken out for natural thawing at room temperature before 24 hours of the test . The geometry sizes of all specimens were measured. Then X-ray was taken to exclude fracture, congenital deformity or metabolic bone diseases. The specimens were tested on axial load, anteflexion load and dorsiflexion load through biomechanical machine before turned into thoracolumbar burst fracture model. The models were fixed through anterior-posterior combined approach or posterior approach and tested on axial load, anteflexion load, dorsiflexion load respectively as done before. The date was recorded to compare mechanical stability of two surgical approach.Result: Through load test data analysed the biomechanical stability, there was statistical significance(p < 0.05)in the axial load, anteflexion load, dorsiflexion load between normal state and fracture state .There was no statistical significance (p>0.05) in the axial load, anteflexion load between anterior-posterior combined approach and posterior approach , but there was statistical significance (p<0.05)in the dorsiflexion load test.Conclusions:1 The stability of specimens in normal state was better than that in internal fixation state.2 There was no statistical significance (p>0.05) in the axial load, anteflexion load between anterior-posterior combined approach and posterior approach, but the mechanical stability of the posterior approach in the dorsiflexion load was slightly worse that that of anterior-posterior approach (p<0.05), because the vertebral spinous, vertebral plate and one side facet joints of the injury vertebral have been removed in the posterior approach. Part 2 Clinical application research of the two operation methods in treating thoracolumbar burst fractureObjective: Evaluate the curative effect of the two operation methods in treating thoracolumbar burst fracture .Method: By extracting 40 patients with thoracolumbar burst fracture treated with anterior-posterior combined approach and posterior approach respectively from January 2005 to august 2010 in our hospital. 30 male cases, 10 female patients, aged 20-61 years, average 37.3 years old; Fracture section: T10 8 cases,T11 12 cases,T12 10 cases,L1 8 cases, L2 2 cases; ASIA classification: A 6 cases,B 11 cases,C 8 cases,D 13 cases,E 2 cases; falling injury28 cases, traffic accident injury 8 cases, the weight scarred 3 cases, other injury 1 case; treated with anterior- posterior combined approach 20 cases, posterior approach 20 cases; Compared the operation time,blood loss in the operation at the two sets of cases . The anterior vertebral height recovery, spinal canal stenosis, Cobb angle correction and neurological recovery were compared between preoperative and postoperative through follow-up.Result:1 40 patients were followed up for 6-48 months, averaging 12.5 months, postoperative wound was primary healing. There were no serious postoperative complications such as aggravation of neurologic symptoms. There were significance difference(p<0.05) in the operation time and blood loss between anterior-posterior combined approach and the posterior approach.2 The anterior vertebral height recovery, spinal canal stenosis, and Cobb angle correction of postoperative had significantly improved than that of the preoperation. There was statistical significance difference(p<0.01)between them. There ware no statistical significance difference in anterior vertebral height recovery, spinal canal stenosis, and Cobb angle correction between postoperative and preoperation(p>0.05).3 Two kinds of operation method could improve neural function at least 1 grade for ASIA classification ,the proportion is 55%( posterior approach) and 65% (anterior-posterior combined approach) respectively,there was no statistical significance difference(p>0.05)between them.Conclusion:1 The operation time and blood loss of posterior approach was less than that of anterior-posterior combined approach;2 Two kinds of operation method both could better correct kyphosis and remove spinal cord compression;3 Two surgical methods ware able to achieve anticipate effect in neurologic recovery,and two methods have the same treatment effect. |
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