Objective To investigate the latest research and the therapeutic development in the injuries to the spine and spinal cord. Methods Literature concerned was reviewed, combined with our own research and clinical experience, to summarize the trend of the researches and their clinical application in the treatment of the injured spine and spinal cord.Results Theposterior approach atlantoaxial stabilization technique changed the conventional wiring technique into the transarticular screw fixation to the plate and pedicle or the lateral mass screw fixation technique. Theclinical application of the transoralpharyngeal atlantoaxial reduction plate fixation technique showed a good effect on the reduction of atlantoaxial dislocation. However, there were no unified criteria for selection of the surgical approach, fixation level, and fusion mode in the treatment of thoracolumbar spinalfractures. Under optimal conditions, both the anterior and the posterior approaches could achieve good clinical effects on decompression and spinal reconstruction. The single level fixation technique showed some advantages in treating certaintypes of thoracolumbar spinal fractures when compared with the traditional cross-sectional fixation. The endoscopy-assistant and image-guiding spinal intervention techniques were evolved in China during these years. In the treatment of the obstinate painful osteoporotic vertebral compressive fracture, percutaneous vertebroplasty and kyphoplasty achieved good results in the pain relief and spinal reconstruction. Numerous basic and clinical researches have given us a further understanding of the medical protection of acute spinal cord injury, and biological treatments have given us new ideas on neural reparation and regeneration. Cell transplantation and gene therapy have become the most promising treatment strategies in this field.Conclusion With the rapid development of spine surgery, the repair and reconstruction ofthe injured spine and spinal cord made a great stride in the recent years.
Objective To biomechanically compare the maximum pull-out strengths among two pedicle screws and three salvage techniques using poly methylmethacrylate (PMMA) augmentation in osteoporotic sacrum, and to determine which PMMA augmentation technique could serve as the salvage fixation for loosening sacral pedicle screws. Methods Eleven sacra were harvested from fresh adult donated cadavers, aged from 66 to 83 years (average 74.4 years) and included 5 men and 6 women. Radiography was used to exclude sacra that showed tumor or inflammatory or any other anatomic abnormal ities. Following the measurement of bone mineral density, five sacral screw fixations were sequentially establ ished on the same sacrum as follows: unicortical pedicle screw (group A), bicortical pedicle screw (group B), unicortical pedicle screw with the traditional PMMA augmentation (group C), ala screw with the traditional PMMA augmentation (group D), and ala screw with a kyphoplasty-assisted PMMA augmentation technique (group E). According to the sequence above, the axial pull-out test of each screw was conducted on a MTS-858 material testing machine. The maximum pull-out forces were measured and compared. The morphologies of PMMA augmented screws after being pulled-out were also inspected. Results The average bone mineral density of 11 osteoporotic specimens was (0.71 ± 0.08) g/cm2 . By observation of the pull-out screws, groups C, D, E showed perfect bonding with PMMA, and group E bonded more PMMA than groups C and D. The maximum pull-out forces of groups A, B, C, D, and E were (508 ± 128), (685 ± 126), (846 ± 230), (543 ± 121), and (702 ± 144) N, respectively. The maximum pull-out strength was significantly higher in groups B, C, and E than in groups A and D (P lt; 0.05), and in group C than in groups B and E (P lt; 0.05). There was no significant difference in pull-out strength between groups A and D, and between groups B and E (P gt; 0.05). Conclusion For sacral screw fixation of osteoporotic patients with bone mineral density more than 0.7 g/cm2, bicortical pedicle screw could acquire significantly higher fixation strength than the unicortical. Once the loosening of pedicle screw occurs, the traditional PMMA augmentation or ala screw with kyphoplasty-assisted PMMA augmentation may serve as a suitable salvage technique.
Objective To evaluate the biomechanical effect of a self-made iliac screw plate on the stability of lumbo-iliac fixation construct before and after fatigue loading. Methods Twelve fresh lumbo-pelvic specimens from donated adult cadavers with formalin embalm were used in the study. According to whether use the iliac screw plate or not, the specimens were randomly assigned into group A (with iliac screw plate, n=6) and group B (without iliac screw plate, n=6). The bone mineral density (BMD) of L1-4 was measured using dual-energy radiograph absorptiometry. The pedicle screw and iliac screw fixation were given at L3-5, and bilateral facetectomy and diskectomy at L5, S1 level were performed to prepare the model of the intervertebral destabilization. The biomechanical testing was conducted on a material testing machine under 0-600 N compression and — 7-7 N · m torsion loading modes for the initial compressive stiffness and torsional stiffness evaluation. And then 20 000 cyclic compressive loading of 40-400 N was given to the specimen, the stiffness evaluation was repeated. Then the maximum pull-out strength of screws at every level was measured and compared. Gross observation and radiological observation were performed during experiment. Results The BMD values of groups A and B were (1.15 ± 0.13) g/cm2 and (1.12 ± 0.11) g/ cm2 respectively, showing no significant difference between 2 groups (t=0.428, P=0.678). All pedicle screws and iliac screws were inserted in good position; no loosening or breaking of screw was observed during loading. After fatigue loading, the incidence of halo ring around the iliac screws of groups A and B was 16.7% (1/6) and 50.0% (3/6), respectively. The compressive stiffness and torsional stiffness after fatigue loading were significantly lower than those in initial state in groups A and B (P lt; 0.05); there was no significant difference in compressive stiffness and torsional stiffness between groups A and B before fatigue loading (P gt; 0.05). However, group A had higher compressive stiffness than group B (t=2.664, P=0.024) after fatigue loading, and there was no significant difference in torsional stiffness between 2 groups (t=0.410, P=0.690). No significant difference was found in screw pull-out strength of pedicle screws at L3, L4, and L5 levels between groups A and B (P gt; 0.05); however, the pull-out strength of the iliac screws in group A was significantly higher than that in group B (t=3.398, P=0.007). In groups A and B, the pull-out strength of L3 screw was significantly lower than that of L4 and L5 screws (P lt; 0.05). In group A, pull-out strength of the iliac screws was significantly higher than that of L3, L4, and L5 screws (P lt; 0.05); in group B, the pull-out strength of iliac screws was significantly lower than that of L4 and L5 screws (P lt; 0.05). Conclusion In the lumbo-iliac reconstruction, the use of iliac screw plate could resist iliac screw loosening, therefore, it has the potential to increase the stability of lumbo-iliac fixation construct.