Progress of decompression surgery for spinal metastases / 中国骨伤

The spine is the most common site of bone metastases from malignant tumors, with metastatic epidural spinal cord compression occurring in about 10% of patients with spinal metastases. Palliative radiotherapy and simple laminectomy and decompression have been the main treatments for metastatic spinal cord compression. The former is ineffective and delayed for radiation-insensitive tumors, and the latter often impairs spinal stability. With the continuous improvement of surgical techniques and instrumentation in recent years, the treatment model of spinal metastases has changed a lot. Decompression surgery underwent open decompression, separation surgery, minimally invasive surgery and laser interintermal thermal ablation decompression. However, no matter what kind of surgical plan is adopted, it should be assessed precisely according to the specific situation of the patient to minimize the risk of surgery as far as possible to ensure the smooth follow-up radiotherapy. This paper reviews the research progress of decompression for spinal metastases.

Finite element analysis of the stress distribution of spinal fusion versus non-fusion surgeries / 中国组织工程研究

BACKGROUND: At present, traditional interbody fusion is still the main method for lumbar degeneration, and non-fusion treatment has achieved rapid development in recent years, but the effects of two kinds of methods on the lumbar biomechanics deserve a further study. OBJECTIVE: To explore the load distribution on the degenerative lumbar vertebrae, and pathogenesis of lumbar spine degeneration through finite element analysis; and to compare the stress distribution on the lumbar vertebrae and treatment outcomes after fusion and non-fusion surgeries. METHODS: The finite element models of four groups were established, respectively, based on the CT images, including normal lumbar spine, lumbar intervertebral disc herniation, and lumbar spine after fusion and non-fusion surgeries. The four groups were modeled in neutral position, lateral flexion, flexion and rotation by workbench 17.0, and the finite element analysis of stress and statics was conducted. RESULTS AND CONCLUSION: (1) The finite element analysis of degenerative lumbar spine showed that the stress of intervertebral disc mainly concentrated on the posterior part of the annulus fibrosus. The degenerative annulus fibrosus easily became thin under stress, thus affecting the lumbar stability. (2) The comparative analysis results found that the finite element results of the lumbar spine after non-fusion surgery were closer to those of the normal lumbar spine. Therefore, non-fusion surgery can achieve better repair outcomes in the treatment of lumbar vertebral degeneration.

Therapy progress of spinal cord compression by metastatic spinal tumor / 中国骨伤

Metastatic epidural compression of the spinal cord is a significant source of morbidity in patients with systemic cancer. With improvment of oncotheray, survival period in the patients is improving and metastatic cord compression is en- countered increasingly often. Surgical management performed for early circumferential decompression for the spinal cord com- pression with spine instability, and spine reconstruction performed. Patients with radiosensitive tumours without spine instabili- ty, radiotherapy is an effective therapy. Spinal stereotactic radiosurgery and minimally invasive techniques, such as vertebro- plasty and kyphoplasty, percutaneous pedicle screw fixation, radiofrequency ablation are promising options for treatment of cer- tain selected patients with spinal metastases.

Single factor analysis of motor dysfunction and imaging and clinical features in metastatic epidural spinal cord compression / 中国骨伤

<p><b>OBJECTIVE</b>To explore the relationship of motor dysfunction of the lower extremities with the imaging appearances and clinical features of metastatic epidural spinal cord compression (MESCCs).</p><p><b>METHODS</b>From July 2006 to December 2007, 26 successive patients with metastases of the thoracic, lumbar and the cervical spine were treated in our department. Forty-three main involved vertebra in all 26 patients were evaluated by magnetic resonance imaging and computed tomography, and were scored according motor dysfunction in this study. Fourteen patients (25 vertebrae) had motor dysfunction.</p><p><b>RESULTS</b>Among 26 patients, 12 cases with visceral metastasis,in which had motor dysfunction in 10 cases; 14 cases without visceral metastasis, in which had motor dysfunction in 4 cases; comparison between two groups, P=0.0079. Among vertebral presence of continuity of 43 main involved vertebrae, 16 vertebrae had motor dysfunction;among vertebral absence of continuity, motor dysfunction occurred in 9 vertebrae, comparison between two groups, P=0.1034. Among vertebral presence of lamina involvement of 43 main involved vertebrae, 11 vertebrae had motor dysfunction; among vertebral absence of lamina involvement, motor dysfunction occurred in 14 vertebrae, comparison between two groups, P=0.020 5. Among vertebral presence of protruding of vertebral posterior wall of 43 main involved vertebrae, 12 vertebrae had motor dysfunction; among vertebral absence of protruding of vertebral posterior wall, 13 vertebrae had motor dysfunction, comparison between two groups, P=0.0334. Among vertebral presence of involvement epidural space of 43 main involved vertebrae, 11 vertebrae had motor dysfunction; among vertebral absence of involvement epidural space, 14 vertebrae had motor dysfunction, comparison between two groups, P=0.003 6. Such factors as age, gender, whether or not received regular chem before admission, back pain degree of metastasis, received regular chem before admission, therapeutic efficacy of primary tumor, number of bony metastases outside spine, number of the main involved vertebrae, level of vertebral metastases location, level of continuous involved vertebrae, vertebral-body involvement, fracture of anterior column, fracture of posterior wall, and pedicle involvement had no effects on incidence of motor dysfunction due to MESCC (P>0.05).</p><p><b>CONCLUSION</b>MESCC with visceral metastases, lamina involvement, presence of outstanding buttocks sign of posterior wall,involvement epidural space tended to cause symptomatic MESCC. Incidence of continuity of main involved vertebrae occurred more frequently in the CUTS compared with other levels of spine.</p>

Diagnosis and treatment of odontoid fracture combined with lower cervical spinal injury / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the mechanism, clinical features and treatment of odontoid fracture combined with lower cervical spinal injury.</p><p><b>METHODS</b>From January 1999 to December 2004, 57 cases of type II or shallow type III odontoid fractures were studied retrospectively. Six cases were found combined with lower cervical injury, the mean age was 54 years, and 4 of the 6 cases were complicated with cervical spondylarthrosis or ankylosing spondylitis. For the lower cervical injury, fracture-dislocation was found in 2 cases, the disruption of disc and ligament was found in 4 cases among which 2 cases were suffered from incomplete spinal cord injury; Both were caused by lower cervical spinal injury. All of the 6 cases were performed with surgery in odontoid fracture and lower cervical spinal injury simultaneously; Lower cervical spinal injuries were stabilized firstly in 2 cases, which responsible for neurological involvement; For the other 4 cases without neurological involvement, stabilization was performed in odontoid fracture firstly in 2 cases, due to inability to achieve reduction of odontoid fracture preoperatively, however, for the another 2 cases with anatomic reduction of the odontoid fracture preoperatively, lower cervical injuries were stabilized firstly.</p><p><b>RESULTS</b>After an average follow-up of 10 months, all cases were obtained solid fusion both in odontoid fracture and lower cervical spinal injury, and without the complications associated with operation and prolonged bed rest. Two cases with neurological defect improved 1 scale in Frankel score.</p><p><b>CONCLUSIONS</b>The incidence of odontoid fracture combined with lower cervical spinal injury is about 10.5% of the odontoid fracture, and it is vulnerable in the elderly patient with cervical spondylarthrosis. MRI should be used routinely for accurate diagnosis. Surgical stabilization is the choice of treatment due to facilitating early rehabilitation and reducing the complications. The surgical schedule is planned according to the fact of neurological involvement and the extent of stability between the odontoid fracture and lower cervical spinal injury.</p>

Development and validation of a finite element model for lumbar motion segment (L4-L5) / 第二军医大学学报

Objective: To develop and validate an accurate three-dimensional geometrical and mechanical finite element(FE) model of the lurabar L4-L5 segment using a new computer-aided designing (CAD) method. Methods: First, a modified "non-seed region segmentation" was done to extract the interest region in the CT image and to obtain a binary image, from which the iso-surface of vertebral body was produced by a discretized marching cubes algorithm. Second, "best cross-section planes" representing the morphologic characteristics of physiological lordosis were used for the initial iso-surface model, forming a "nonregular piecewise subspace". This subspace and the embedded iso-surface model were subsequently transformed by local affine transforms to a "regular subspace", in which a surface mesh of high quality was generated quickly. Finally, a reverse transform procedure was employed to restore the original three-dimensional (3D) image of the lumbar surface mesh of lumbar L4-L5. All coordinate dada of nodal points and message of triangular patches of the surface model were then subjected to ANSYS for the three-dimensional FE mesh construction. An accurate 3D non-linear FE model of lumbar motion segment (L4-L5) was developed and validated against published data. Results: The constructe d FE model of lumbar L4-L5 consisted of 94 794 solid elements, 1 196 link elements, 1 170 shell elements, 768 target elements and 464 contact elements, and included geometrical, material and contact non-linearities. The predicted results of lumbar L4-L5 segment were closely correlated with published results of experimental biomechanics in terms of axial displacement, segment rotation and intradiscal pressure under similar load condition. Conclusion: Based on advanced algorithm, this constructed surface model of L4-L5 segment is capable to perform whole digitalized binary image extraction and reconstruction of the lumbar surface with excellent simulation results.