Wang B

Factors and revision strategy for failure of thoracolumbar spine internal fixation after burst fracture

OBJECTIVE To analyze the reasons for the failure of thoracolumbar spine internal fixation after burst fracture, and to discuss the strategy for revision surgery. METHODS From January 2005 to September 2010, 21 patients with thoracolumbar burst fracture received revision surgery after the failure of internal fixation. The etiology included loose of the fixation after anterior surgery in 4 patients, involving malunion with severe kyphosis in 1 patient, pedicle screw malposition in 3, fracture of adjacent segment vertebra in 2, broken of the fixation as non-union of the fracture vertebra in 10 comprising obvious kyphotic deformity in 5, and 2 had developing kyphosis for over distraction of the vertebra followed by pseudarthrosis after removing the internal fixation. After the first operation, symptoms remained in 6 patients, deteriorated in 7, light to moderate improved in 8. Surgical procedures such as anterior corpectomy and reconstruction, replacement of the internal fixation and canal decompression, vertebroplasty, and posterior pedicle subtraction osteotomy were directed based on individual situation. RESULTS Patients were followed-up for 6-68 (27.0±13.2) months, and demonstrated solid fusion 6 to 12 months postoperatively. No failure of the internal fixation reccurred. No major complications or deterioration of neurologic status were noted. At the last follow-up, the improvement of Frankel grade was 0-2 (1.3±0.7). The mean visual analog scale (VAS) dropped down from 7.6 to 2.1, and the mean oswestry disability index (ODI) decreased from 48.7 to 10.3. Preoperative angle of 7 kyphotic deformity patients was 10 degree-75 degree (42.5 degree±15.3 degree), and was improved to -3 degree-10 degree (2.3 degree±3.7 degree). At the last follow-up, the loss of correction was 0 degree-1.3 degree (0.7 degree±0.3 degree), with the correction rate of 92.3%. CONCLUSION Solid reconstruction of the anterior and middle column of the spine is the imperative procedure to prevent failure of internal fixation in thoracolumbar burst fractures. Revision surgery with reasonable strategy is beneficial and rewarding with few complications.

Surgical management of vertebral sarcoidosis

OBJECTIVE To investigate the clinical characteristics, diagnostic foundation and treatment of vertebral sarcoidosis. METHODS The clinical data of 13 patients with vertebral sarcoidosis who received anterior debridement and instrumentation were retrospectively analyzed. RESULTS The onset of progressive pain in the pathological region was common in the 13 patients. Neurologic deficit existed in 4 cases. Radiographic study showed multiple vertebral bone destructions, and no other systemic lesions were found. Surgical indications were progressive vertebral destruction, spinal instability or neurological deficit. Anterior vertebra resection, and autologous bone grafts fusion with internal fixation were done. No operative mortality and major complications occurred. Diagnosis was confirmed in all patients by pathological exam. After the surgery, metacortandracin treatment was given routinely for 1 year. Patients were followed up for 12-52 (median 26) months, and pain and neurological symptoms were alleviated. Visual analog scale (VAS) score was 7-10 (median 8) points preoperatively, which dropped to 0-4 (median 2) points postoperatively. All patients showed successful bone fusion with no recurrence. CONCLUSION For vertebral sarcoidosis associated with progressive instability and/or neurological symptoms, surgical intervention combined with steroid therapy is safe and effective.

[Effect of transfection of enhanced green fluorescent protein gene on neuron-like differentiation of rat mesenchymal stem cells].

OBJECTIVE To determine the effect of transfection of enhanced green fluorescent protein (EGFP) on neuron-like differentiation of rat mesenchymal stem cells (rMSC) with plasmid vector. METHODS In vitro cultured rMSC was transfected with plasmid vector containing EGFP, and its surface marker and differentiation neuron-like cells were detected. Results There was no significant difference in the morphology and surface markers between the EGFP-rMSC and rMSC. The cell surface markers of EGFP-rMSC including expression of CD44(+),CD11b (-) and CD45(-) remained similar to those of rMSC. EGFP-rMSC presented the differentiated potential to neuron-like cells. There was no statistical difference in the positive ratio of neuron-like differentiation between the EGFP-rMSC and rMSC (P> 0.05). CONCLUSION EGFP does not affect the neuron-like differentiation potential of rMSC, and can be used as the trace marker in the study of differentiation potential of rMSC.