The Biomechanical And Clinical Study Of Three-Column Reconstruction After The Resection Of Thoracolumbar Spinal Tumor

Resection and stability reconstruction of spinal tumor is an important topic in spinal surgery. The objection of this study is to evaluate and compare the stability provided by four combined anterior and posterior three-column reconstruction methods after the resection of thoracolumbar spinal tumor, and to provide warrant for clinical application. Biomechanical studyIn this study, six fresh-frozen human cadaveric thoracolumbar spines (T9-L3) were used to make model of T12 curettage and total spondylectomy. On the basis of multilevel posterior pedicle screw instrumentation from T10-L2, four anterior reconstruction methods were performed. The specimens were tested in a nondestructive manner load, it produce axial compression and the following six degrees of freedom: flexion, extension, torsion right/left and lateral bending right/left. Data were captured using CCD and an adjacent desktop computer. The stability was analyzed by Digital-Image-Correlation Technique.Six fresh-frozen human cadaveric thoracolumbar spines (T9-L3) were inspected by plain radiographs to ensure specimens the absence of structural spinal disorders, previous neoplastic disease, or spinal surgery. In addition, these images confirmed the correct anatomic sagittal and coronal alignment of the specimen. After intact specimen (named A group) analysis, T12 curettage was performed and PMMA cement filled the cavity of T12 and multilevel posterior pedicle screw instrumentation from T10-L2 (named Fl group). After group Fl analysis, a total spondylectomy was performed at T12. Three reconstruction techniques were tested: l)anterior instrumentation (adjustable titanium artificial centrum, Modul'lcs) and multilevel posterior pedicle screw instrumentation (XIA) from T10-L2(named F2 group);2) anterior instrumentation (Modul'lcs) and anterior plate (Centaur) at T11-L1 with multilevel posterior pedicle screw instrumentation from T10-L2(named F3 group);and 3) anterior cement (Palacos R-40) and screw construct (T12) with multilevel posterior pedicle screw instrumentation from T10-L2(named F4 group). The order oftesting these nondestructive loads was randomized in each of the reconstruction stages and in each individual specimen. The result shows all group provided more stability to the specimen than intact spine in all loading modes (P<0.001) . No statistical difference was found among all reconstruction group (P>0.05) except of group F3 provided more stability than group Fl in flexion loading modes (P< 0.05). Clinical studyIn this retrospective study, the outcomes of posterior or combined anterior and posterior approaches operation performed 21 patients with the thoracolumbar spinal tumor. Of these, tumor vertebra curettage was performed in 4 cases. Total spondylectomy was performed 17 cases. Fourteen case were operate by posterior approach, seven case adopted the combined anterior and posterior approach;All patients were decompress and instrumentation. Of these, on the basis of multilevel posterior pedicle screw instrumentation, anterior reconstruction methods have following three categories: five cases were adjustable titanium artificial vertebrae, two cases were combined adjustable titanium artificial vertebrae and anterior plate and 14 cases were PMMA cement. In times of operation, we recorded operative time, intra-operative blood loss.The plain radiographs was performed all patients after postoperative 1 week,3 and 6 months, MRI inspect in postoperative 6 and 9 months. All of patients were followed up from 6-42 months. The result showed, we compared anterior cement reconstruction and other reconstructive methods, anterior cement reconstruction has the advantage of simple assembling, less operation time and less blood lost. Pain improved or vanishes in all of patients in postoperative 1 week. No patients worsened neurologically, and 14 cases incomplete spinal cord injuries improved in postoperative 3 months. No complication caused by implants has been founded. All patients achieved solid fusion radio graphically. Anterior cement hasn't obviously cinched and displace.Conclusion: the results of biomechanical and clinical study suggest that the "Combined anterior and posterior reconstruction using a cement construct" procedure is a reliable and safe technique, it can achieve anterior decompression ofthe spinal canal and three column reconstruct to restore spinal stability through posterior a single approach in highly selective patients with spinal tumor. PMMA cement has the advantage over traditional anterior reconstruction techniques in that it can be inserted using a posterior approach and provided favorable biomechanics character. This technique has the advantage of simple assembling, less operation time and less operation wound.