Effective analysis of the posterior vertebral pedicle screw fixation, vertebral body removal, decompression and titanium mesh reconstruction for the treatment of the lower lumbar fractures / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the effect of the treatment of the lower lumbar fractures by posterior vertebral pedicle screw fixation, vertebral canal decompression,bone graft and titanium mesh reconstruction.</p><p><b>METHODS</b>From January 2006 to December 2008, 22 patients with lower lumbar fractures were treated by posterior vertebral pedicle screw fixation, vertebral canal decompression, bone graft and titanium mesh reconstruction at same period. There were 18 males and 4 females with an average age of 43.8 years ranging from 22 to 63 years old. The injured vertebrae were L3 in 11 cases, L4, in 8 cases, and L5 in 3 cases. The operative time, blood loss, the preoperative and postoperative vertebral height,sagittal index, and the lumbar lordosis angle were recorded and evaluated.</p><p><b>RESULTS</b>The operative time was 3 to 4.2 hours (means 3.6 h). The blood loss averaged 1300 ml (900 to 1500 ml). The preoperative and postoperative sagittal index were (57.5 +/- 7.6)% and (93.5 +/- 8.1)%, respectively. The preoperative and postoperative lumbar lordosis angle were (34.3 +/- 7.3) degrees and (38.5 +/- 9.8) degrees, respectively. All patients were followed up for 10 months to 3 years (means 2.6 years). No fixation were failed,the segment of titanium mesh reconstruction obtained bone healing, no pseudoarticulation formation. At the last time of followed-up, 15 patients with nerve injuries were evaluated according to Frankel grade, there were 10 cases in grade E, 4 in D, 1 in C. According to the low back outcome scores (LBOS), the results were excellent in 20 cases, good in 1, fair in 1.</p><p><b>CONCLUSION</b>The stability of the lower lumbar spine can be reconstructed by bone graft and titanium mesh combined with transpedicular screw fixation through a posterior approach. The decompression and vertebral body removal can also be performed in this approach. The recovery of the vertebral height and lumbar lordosis can prevent the delayed neurological deficit and traumatic kyphosis.</p>

Biomechanical performance of different wires and cable fixation devices in posterior instrumentation for atlantoaxial instability / 南方医科大学学报

<p><b>OBJECTIVE</b>To compare the biomechanical performances of different wires and cable fixation devices in posterior instrumentation for atlantoaxial instability, and test the effect of different fixation strengths and fixation approaches on the surgical outcomes.</p><p><b>METHODS</b>Six specimens of the atlantoaxial complex (C0-C3) were used to establish models of the normal complex, unstable complex (type II odontoid fracture) and fixed complex. On the wd-5 mechanical testing machine, the parameters including the strength and rigidity of anti-rotation, change and strength of stress, and stability were measured for the normal complex, atlantoaxial instability complex, the new type titanium cable fixation system, Atlas titanium cable, Songer titanium cable, and stainless wire.</p><p><b>RESULTS</b>The strength and rigidity of anti-rotation, change and strength of stress, stability of flexion, extension and lateral bending of the unstable atlantoaxial complex fixed by the new double locking titanium cable fixation system were superior to those of the Songer or Atlas titanium cable (P<0.05) and medical stainless wire (P<0.05). Simultaneous cable fastening on both sides resulted in better fixation effect than successive cable fastening (P<0.05). Better fixation effect was achieved by fastening the specimen following a rest (P<0.05).</p><p><b>CONCLUSIONS</b>The fixation effects can be enhanced by increased fastening strengths. The new type double locking titanium cable fixation system has better biomechanical performance than the conventional Songer and Atlas titanium cables. Fastening the unstable specimens after a rest following simultaneous fastening of the specimen on both sides produces better fixation effect.</p>

Anti-rotation biomechanical study of wire and various cable system in the posterior brooks instrumentation for atlantoaxial instability / 中国骨伤

<p><b>OBJECTIVE</b>To compare the anti-rotation biomechanical performances of wire and various cable fixation devices currently used in the posterior Brooks instrumentation for atlantoaxial instability.</p><p><b>METHODS</b>In this experiment,six specimens of the atlantoaxial complex (Occipital-C3) were used. The models of the normal complex,unstable complex (type II odontoid fracture) and fixed complex were established. On the WD-5 mechanics experimental machine,the parameters including the strength and rigidity of anti-rotation were quantified for the normal complex (group N),the atlantoaxial instability complex (group M), the new type Titanium cable (group A), Atlas titanium cable (group B), Songer Titanium cable (group C), stainless wire(group D).</p><p><b>RESULTS</b>The max strength of A, B, C, D groups was 12.5, 11.3, 11.52, 11.55 N x m respectively, the max rigidity was 58.81, 53.17, 54.11, 54.35 N x cm/deg respectively. The strength and rigidity of anti-rotation, compare to the unstable atlantoaxial complex which were fixed by the new double locking Titanium cable fixation system were superior to those of normal complex, instability complex, Songer or Atlas Titanium cable (P < 0.05).</p><p><b>CONCLUSION</b>Having been changed the locking method, the anti-rotation biomechanical characteristics of the new type double locking Titanium cable fixation system are superior or similar to the traditional Songer or Atlas Titanium cable.</p>