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Objective:To investigate the physicochemical and biological properties of different magnesium modified calcium phosphate bone cements.Methods:The different magnesium modified calcium phosphate bone cements were divided into magnesium citrate, magnesium lactate, magnesium malate, magnesium phosphate and magnesium glycinate groups, each of which was added with different magnesium agents in the proportion of 0%, 1%, 3% and 5% of the total weight of calcium phosphate bone cements. The initial and final setting time, injectability, anti-collapse performance and compressive strength of different magnesium modified calcium phosphate bone cements were tested. Furthermore, the screened bone cement extracts were used to culture with third generation osteoblasts. Bioactivity assays were performed using the Cell Proliferation and Toxicity Assay Kit (CCK-8). Alkaline phosphatase (ALP) staining and Alizarin Red S (ARS) staining were performed on osteoblasts to observe the osteogenic activity of magnesium malate modified calcium phosphate bone cements.Results:The addition of different proportions of different magnesium agents led to the shortening of the initial and final setting time of modified calcium phosphate bone cements. Moreover, the final setting time of 5% magnesium malate modified calcium phosphate bone cements was the shortest (<40 minutes), which was significantly shorter compared with other magnesium agents in the same proportion (all P<0.05). With the addition of different magnesium agents in different proportions, the injectability of bone cements was gradually increased, and the injectability of 5% magnesium malate calcium phosphate bone cements reached the highest for (87.3±1.9)%, which was significantly increased compared with other magnesium agents in the same proportion (all P<0.05). The anti-collapse performance of bone cements was decreased with the addition of different magnesium agents in different proportions. Magnesium citrate, magnesium phosphate and magnesium glycinate modified calcium phosphate bone cements could not resist the flushing of deionized water. In particular, magnesium malate modified calcium phosphate bone cements had the best anti-collapse performance, with the maximum weight loss rate for only (9.8±2.3)% after 30 minutes of deionized water flushing, which was better than the rest of the groups (all P<0.05). The compressive strength of magnesium lactate and magnesium phosphate modified calcium phosphate bone cements showed a decrease compared with original calcium phosphate bone cements, while the compressive strength of magnesium citrate and magnesium malate modified calcium phosphate bone cements was significantly increased compared with original calcium phosphate bone cements, of which 3% magnesium malate modified calcium phosphate bone cements had the greatest compressive strength of (6.2±0.2)MPa, significantly higher than the rest of the groups (all P<0.05). The sieve test yielded magnesium malate modified calcium phosphate bone cement, which had a weight loss of (27.0±0.9)% at 35 days in vitro. The release of magnesium ions was increased with increasing magnesium malate dose in the in vitro environment of magnesium malate modified calcium phosphate bone cements in different ratios. A stable magnesium ion release was achieved within 35 days.Also, the pro-proliferative and osteogenic effects of modified calcium phosphate bone cements on osteoblasts were more obvious with increase of magnesium malate dose. For 5% magnesium malate modified calcium phosphate bone cements, the cell number, ALP staining area ratio and calcium nodule area ratio were significantly increased compared with the groups in the proportion of 0% and 1% magnesium malate (all P<0.05). Conclusions:Among magnesium citrate, magnesium lactate, magnesium malate, magnesium phosphate and magnesium glycinate modified calcium phosphate bone cements, magnesium malate modified calcium phosphate bone cements have relatively suitable setting time, excellent anti-collapse performance and mechanical strength. Meanwhile, 5% magnesium malate modified calcium phosphate bone cements have better biological activity among different ratios of magnesium malate modified calcium phosphate bone cements, suggesting a potential value for clinical application.
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BACKGROUND: Lumbar spondylolysis is the common cause of teenagers' low back pain. It should apply internal fixation if conservative treatment is invalid. There are a variety of surgeries, which aims to alleviate pain and bony fusion of pars defect.OBJECTIVE: To observe clinical outcome of bone graft of pars defect plus temporary single segmental pedicle screw rod fixation for adolescent lumbar spondylolysis.METHODS: A total of 32 adolescent patients of lumbar spondylolysis were treated by bone graft of pars defect plus temporary single segmental pedicle screw rod fixation. All the patients had bilateral spondylolysis. 20 patients had no lumbar spondylolisthesis, while the others had I° spondylolisthesis. All the patients received lumbar radiograph, CT and MRI. Visual analogue scale and Oswestry disability index were utilized to evaluate pain improvement before and after operation. MacNab was used to assess efficacy. Bone graft healing at isthmus was observed with lumbar CT after fixation. The internal fixation was removed after bone fusion, then the motion of the fixed segment and the degeneration of adjacent intervertebral disc occurred were recorded.RESULTS AND CONCLUSION: (1) Completed bone fusion of pars defect was achieved in all the patients. The average period of bone union was 7.4 months. (2) The visual analogue scale and Oswestry disability index scores were significantly improved after surgery in all patients (P < 0.05). (3) The fixed segment reserved the motion after internal fixation removal. The signal of adjacent intervertebral disc of fixed segment had no changes compared to preoperative MRI. (4) Bone graft to repair isthmus defect plus temporary single segmental screw rod fixation for adolescent lumbar spondylolysis is very effective, the bone fusion is completed, and temporary fixation may effectively alleviate the degeneration of adjacent disc.
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0.05).Operation time in group A was shorter than that in group B,with significant difference(P0.05).No postoperative complication was found in two groups.[Conclusion]Unilateral TLIE technique has achieved satisfying postoperative effect compared with bilateral TLIF,with a good prospect in clinical application.
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Objective To summarize the experiences of the diagnosis and treatment of the intraspinal tumors. Methods One hundredand twenty-three cases of the intraspinal tumors were analyzed retrospectively. Results The intraspinal tumors in those patients included meningiomas/neurofibroma in 32 cases (19.5%), neurinoma in 32 cases (26.0%), ependymoma in 8 cases (6.5%), astrocytoma in 13 cases (10.6%), lipoma in 10 cases (8.1%), metastatic tumors and hemangioma each in 5 cases (4.1%), arachnoid cyst in 9 cases (7.3%), and others in 17 cases (13.8%). The extramedullary subdural, epidural and intramedullary tumors accounted for 56.9%, 21.1% and 22.8%. According to the locations, 30.1% tumors located at cervical region, 37.4% at thoracic region, 19.5% at lumbar region and 13.0% at sacral segments. The total removal rates of tumors were 69.1% (the total removal rates of extramedullary tumors were 70.1%, and the removal rates of intramedullary tumors were 60.7%).The improvement rates of different degree of movement, sense and sphincter function were 75.2%, 73.8% and 77.8%. Conclusion Most of the intraspinal tumors are benign, and the surgical outcome is satisfied. The keys of therapeutic efficacy were MRI and microsurgical techniques application. The spinal stability reconstruction is in the extreme need if spinal stability is breached in surgery.
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@#Objective To explore effect of Axis internal fixation system while decompression and fusion for the treatment of timeworn atlantoaxial dislocation with incomplete spinal cord injury.Methods 29 cases of timeworn atlanto-axial dislocation with incomplete spinal cord injury underwent decompression fusion and Axis internal fixation with a 7～46 months (mean 20 months) flowing-up.ResultsAfter treatment, all patients got completed fusion, there was no deterioration of neurofunction, and rate of JOA scores increased was 78.6%.ConclusionAxis internal fixation system can provide immediately a rigid stability and maintain axial correction for the segment ahile decompression and fusion for the treatment of timeworn atlantoaxial deslocation with incomplete spinal cord injury.