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>

The surgical treatment of severe adolescent idiopathic cervical kyphosis / 中华外科杂志

<p><b>OBJECTIVE</b>To summarize the clinical characteristics of severe adolescent idiopathic cervical kyphosis and the operation method.</p><p><b>METHODS</b>A retrospective study was performed in 12 adolescent patients with severe cervical kyphosis treated from July 2003 to January 2007. Preoperative the Cobb angle of kyphosis range from 55 degrees to 73 degrees (average 61 degrees ). According to the angles between the posterior vertebral body tangents at every involved level on lateral cervical radiograph in extension, the osteotomy angles and range of lamina and facet were decided. The anterior release and posterior osteotomy were performed firstly. Then skull traction was maintained in order to correct the deformity as long as possible, fusion and internal fixation was completed after 7-10 days. The cervical coronal and sagittal planes X-rays and the MR were hold after operation 3 days, 3 months, 6 months, 1 year and 2 years. At the same time the treatment result, bone fusion and the instrumentation were followed up, and the symptoms were compared between pre-operation and post-operation.</p><p><b>RESULTS</b>The defect appearance of the patients was improved significantly, with the total disappearance of neck pain and improvement of nerve function. Post-operational cervical spine MR showed that the physiological curve of cervical spine was restored, cerebral spinal fluid line was clear in the kyphosis area and no spinal cord compression was found. X-ray imaging of post-operation 3 d showed that Cobb angle ranged from -12.3 degrees to 11.2 degrees with an average of -2.0 degrees . Beside one patient's AISA score was D, other patient's AISA score was E.</p><p><b>CONCLUSIONS</b>The severe adolescent idiopathic cervical kyphosis has its own clinical manifestation. It is an ideal treatment to completely assess the deformity, have staging operation and skull traction between two operations.</p>

Anterior decompression for the treatment of cervical spondylotic myelopathy associated with ossification of posterior longitudinal ligament / 中华外科杂志

<p><b>OBJECTIVE</b>To study the technique and effect of anterior decompression for the treatment of cervical spondylotic myelopathy associated with ossification of posterior longitudinal ligament (OPLL).</p><p><b>METHOD</b>Sixty-one patients (42 male and 19 female, 45 - 74 years with mean age of 57 years old) underwent anterior decompression for the treatment of cervical spondylotic myelopathy associated with OPLL. Among them, OPLL was definitely diagnosed in 49 patients preoperatively, and was found during the operation in the other 12 patients. The occupying rate of OPLL ranged 32%-70% with an average of 52%. The preoperative JOA scores ranged 4 - 14 points with an average of 9.6 points. In additional to conventional decompression, the ossification was removed completely after discectomy and corpectomy.</p><p><b>RESULTS</b>Corpectomy was performed in 41 cases, discectomy in 6 cases and combination of corpectomy and discectomy in 14 cases. The follow-up of all patients ranged from 6 to 36 months (mean 16 months). The postoperative JOA scores ranged 8-16 points with an average of 12.8 points. The neurological improvement rate ranged from 25.0% to 87.5% with an average of 65.2%. The transient leakage of cerebrospinal fluid (CSF) occurred in 5 cases, and stopped after conservational treatment. No neurological deterioration developed.</p><p><b>CONCLUSIONS</b>The difficulty and risk of anterior decompression are significantly increased in the patients with cervical spondylotic myelopathy associated with OPLL. Remove of ossification after corpectomy and discectomy could provide complete decompression and better results.</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>

Change of motor evoked potential of the diaphragm after graded upper cervical spinal cord injury in rats / 中华外科杂志

<p><b>OBJECTIVE</b>To study the change of motor evoked potential of the diaphragm after graded upper cervical cord injuries and analyze the prognosis of the respiratory function after upper cervical cord injuries by MEP.</p><p><b>METHODS</b>The C(3, 4) spinal cord of 40 SD rats were injured with modified Allen method by weight drop force of 30 gcf, 50 gcf, 80 gcf, 100 gcf. The change of latent and amplitude of MEP of the diaphragm was observed before and after the spinal cord injuries (followed up for 1 month). At the same time, the femoral arterial blood of 0.2 ml was drawn. The pH value, the partial pressure of oxygen, the partial pressure of carbon dioxide, and the saturation of the blood oxygen were monitored. The change of the respiratory function was evaluated in the rats after cervical cord injuries. The relationship between the recovery of the respiratory function and the latent or amplitude was analyzed.</p><p><b>RESULTS</b>The MEP wave of the diaphragm was stable before the upper cervical spinal cord injury in the rats. It was usually composed of a positive and negative wave. The latent period and peak-peak amplitude of wave were (3.13 +/- 0.29) ms and (6.78 +/- 3.48) mv. The latent period of the diaphragms MEP in rats change with graded upper cervical cord injuries significantly, the more sever the injury, the longer the latent period. There were obvious relationship between the change of the latent period and the recovery of the respiratory function. When the latent period prolonged 101%, the respiratory function is hardly to recovery.</p><p><b>CONCLUSIONS</b>MEP can objectively and sensitively reflect the injury extent of the respiratory function when upper cervical cord is injured. It would be a reliable index to evaluate the long-term prognosis of respiratory function.</p>

An experimental study of motor evoked potentials of the diaphragm elicited by transcranial electric stimulation / 中华物理医学与康复杂志

Objective To study the characteristics of the transcranial electric stimulation(TES)-elicited motor evoked potentials(MEP)recorded from different points of the diaphragm,and to determine the optimal record- ing site in the diaphragm.Methods One EEG electrode was placed subcutaneously in the midline of the skull as stimulation electrode and another EEG electrode was inserted into hard palate submucously as cathode in 30 male rats.And single square wave electrical pulse was used for stimulation.The stimulation intensity was 15 mA,the du- ration of the pulse was 0.2 ms,and the stimulating interval was 200 ms.The concentric needle electrode were insert- ed into the following eight sites:the medial,intermediate,lateral crura of the diaphragm,the junction of the posterior axilla line and the inferior border of the eleventh rib,the junction of the anterior axilla line and the inferior border of the ninth rib,the junction of the intermediate line of the clavicle and the inferior border of the eighth rib,the junction of the para-sternal line and the inferior border of the seventh rib,the pars sternalis.The MEP was recorded from each point,respectively.The optimal sites of the diaphragm MEP were found and recorded.Results The MEPs were re- corded from each of the 8 sites of the diaphragm in all the rats after TES.There was no statistically significant differ- ence among the latencies of every site.But the amplitude varied from 6.08?0.46 mV in maximum along the inferior border of the ninth rib at the anterior line of the axilla to the minimum of O.91?0.03 mV at the pars sternalis. Conclusion It is safer to insert the needle along the inferior border of the ninth rib at the anterior line of the axilla, because there was certain distant from the folding part of the pleura and the amplitude of the recorded wave at this point is maximal.