[Construction and stability analysis of finite element model for spinal canal reconstruction with miniplates fixation].

OBJECTIVE: To establish the finite element model of spinal canal reconstruction and internal fixation,analysis influence of spinal canal reconstruction and internal fixation on spinal stability,and verify the effectiveness and reliability of spinal canal reconstruction and internal fixation in spinal canal surgery. METHODS: A 30-year-old male healthy volunteer with a height of 172 cm and weight of 75 kg was selected and his lumbar CT data were collected to establish a finite element model of normal lumbar L3-L5,and the results were compared with in vitro solid results and published finite element analysis results to verify the validity of the model. They were divided into normal group,laminectomy group and spinal canal reconstruction group according to different treatment methods. Under the same boundary fixation and physiological load conditions,six kinds of activities were performed,including forward bending,backward extension,left bending,right bending,left rotation and right rotation,and the changes of range of motion (ROM) of L3-L4,L4-L5 segments and overall maximum ROM of L3-L5 were analyzed under the six conditions. RESULTS: The ROM displacement range of each segment of the constructed L3-L5 finite element model was consistent with the in vitro solid results and previous literature data,which confirms the validity of the model. In L3-L4,ROM of spinal canal reconstruction group was slightly increased than that of normal group during posterior extension(>5% difference),and ROM of other conditions was similar to that of normal group(<5% difference). ROM in laminectomy group was significantly increase than that in normal group and spinal canal reconstruction group under the condition of flexion,extension,left and right rotation. In L4-L5,ROM in spinal canal reconstruction group was similar to that in normal group(<5% difference),while ROM in laminectomy group was significantly higher than that in normal group and spinal canal reconstruction group(>5% difference). In the overall maximum ROM of L3-L5,spinal canal reconstruction group was only slightly higher than normal group under the condition of posterior extension(>5% difference),while laminectomy was significantly higher than normal group and spinal canal reconstruction group under the condition of anterior flexion,posterior extension,left and right rotation(>5% difference). The changes of each segment ROM and overall ROM of L3-L5 showed laminectomy group>spinal canal reconstruction group>normal group. CONCLUSION: Laminectomy could seriously affect biomechanical stability of the spine,but application of spinal canal reconstruction and internal fixation could effectively reduce ROM displacement of the responsible segment of spine and maintain its biomechanical stability.

[Progress on laminoplasty in spinal canal disease].

Surgery is the preferred method for the treatment of spinal canal disease, surgical method involves laminectomy and laminoplasty. The ideal spinal surgery not only should fully expose the spinal canal, completely resect the occupied position and remove the spinal cord compression, but also should maintain the stability of spinal biomechanics. Because of the different realization of clinician to safeguard and rebuild the spinal stabilization during opertion of spinal canal disease, and choice of surgical method and how to maintain the stability of spine biomechanics has become a hot of research in this field. Many scholars have studied it in order to reduce the influence of laminectomy on the spinal stability. Laminoplasty can directly relieve the nerve roots compression caused by increasing or reconstruction of vertebral canal volume, and allow the migration of spinal cord to dorsum and depart from disc and vertebral body. Laminoplasty not only can fully expose and decompress during operative, but also may prevent the postoperative spinal instability. In addition to these condition of extensive disease, severe bone destruction or combined with osteoporosis, the laminoplasty is the most ideal method for single spinal canal disease in theoretically.

Comparison of the short-term efficacy between docetaxel plus carboplatin and 5-fluorouracil plus carboplatin in locoregionally advanced nasopharyngeal carcinoma.

OBJECTIVE: Platinum-based chemotherapy in combination with radiotherapy is a standard treatment strategy for locoregionally advanced nasopharyngeal carcinoma (NPC). This study aimed to investigate the long-term efficacy and tolerability of inductive chemotherapy with docetaxel plus carboplatin (TC) or 5-fluorouracil plus carboplatin (FC) followed by concurrent radiation therapy in patients with NPC. METHODS: Patients (N=88) were randomized to receive TC or FC as inductive therapy followed by concurrent radiotherapy (60-70 Gy) with two cycles of carboplatin (area under the curve =5 mg·h/L). Patients were followed up for 8 years. Primary end point was progression-free survival (PFS). Secondary end points included overall survival (OS), toxicity, tumor response, distant metastasis-free survival, and local recurrence-free survival. RESULTS: At the end of the follow-up period, 31 patients died, 32 had disease progression, eleven had cancer recurrence, and 25 had distant metastasis. Overall, there was no difference between treatment groups with regard to response or survival. We found that following induction and concurrent chemoradiotherapy, the majority of patients showed a complete response (~96%-98% for induction therapy and 82%-84% for comprehensive therapy) to both therapies. PFS and OS were also similar between groups. The rate of PFS was 63.6% for both FC and TC and that of OS was 65.9% and 63.5%, respectively. The overall incidence of grade 3-4 adverse events in the TC group (20.5%) was higher than in the FC group (10.7%). Neutropenia and leukopenia were the most common grade 3-4 adverse events in the TC group, and mucositis was the most common in the FC group. CONCLUSION: These data indicate that TC and FC therapies have similar efficacy in treating locally advanced NPC and both are well tolerated.