BACKGROUND:Related studies have shown that after kyphoplasty with bone cement injection, the vertebral height restoration is closely related to the injury time. Surgical timing also has an important influence on the incidence of postoperative complications. OBJECTIVE:To compare the clinical efficacy of kyphoplasty with bone cement injection at 2 and 2-4 weeks after thoracolumbar vertebral compression fractures, and to investigate the best timing for kyphoplasty. METHODS:Eighty-two thoracolumbar fracture patients, aged 55-85 years old, were included. Thirty-nine cases were subjected to kyphoplasty with bone cement injection within 2 weeks after injury. Another 43 cases were subjected to kyphoplasty with bone cement injection within 2-4 weeks after injury. The visual analog scale score, restoration of anterior and central vertebral height, volume and leakage of bone cement after treatment were compared between two groups. At 6 months after treatment, the daily activities of patients in the two groups were evaluated using Oswestry disability index. RESULTS AND CONCLUSION:Immediately and at the 6th month after treatment, the scores on the visual analog scale and the Oswestry disability index were lower than those before treatment (P < 0.05). The visual analog scale score immediately after treatment in the treatment group within 2 weeks was higher than that in the treatment group within 2-4 weeks (P< 0.05). After 6 months of treatment, there was no significant difference in the restoration rate of anterior and central vertebral height between these two groups, but the loss rate of the anterior and central vertebral height in the treatment group within 2 weeks was lower than that in the treatment group within 2-4 weeks (P< 0.05). Bone cement injection volume and leakage rate had no significant differences between two groups. These results demonstrate that patients appeared to have obvious pain after percutaneous kyphoplasty with bone cement injection within 2 weeks, but the percutaneous kyphoplasty with bone cement injection had smal influence on the short-term loss rate of vertebral height. Therefore, percutaneous kyphoplasty with bone cement injection with 2 weeks after injury is the optimal treatment timing for patients with thoracolumbar compression fractures.

BACKGROUND:Previous studies have shown that home-made porous tantalum has non-toxicity and good biocompatibility, and can promote osteogenesis. Herein, we explore the mechanisms of tantalum-bone interface osseointegration.OBJECTIVE:To observe the morphological characteristics and expressions of integrin β1 and fibronectin on the interface between porous tantalum and bone tissues after implantation into the right rabbit femur, and to evaluate the biological mechanisms of tantalum-bone interface osseointegration.METHODS: Animal models of bilateral femoral condyle defects were made in Japanese big ear rabbits. Porous tantalum rod and allogeneic bone were respectively implanted into the left (experimental group) and right (control group) femur of rabbits. The animal specimens at the bone defect region were taken and made into paraffin sections and hard tissue sections at postoperative 2, 4, 8 weeks for morphological observation of new bone at the junction between the tantalum rod and host bone under light microscope, for osteogenic observation of the tantalum-bone interface under scanning electron microscope, and for immunohistochemical detection of integrin β1 and fibronectin expression.RESULTS AND CONCLUSION:Porous tantalum was bonded closely with the host bone. The loose and thick fibrous capsule was observed in the early stage and became thinner in the late stage shown by hematoxylin-eosin staining. The new bone was visible on tantalum-bone interface. Hard tissue slicing observation showed that the new bone was seen on the porous tantalum-bone interface, blood capillaries grew into the pores at postoperative 2 weeks and the pores were full of new bone tissues at postoperative 4 and 8 weeks. Under the scanning electron microscope, the osteoblasts appeared on the tantalum surface and in the pores at the early stage, and bone maturation and lamelar bone were seen at the late stage. The immunohistochemical results showed that the expression of integrin β1 in the experimental group was significantly lower than that in the control group at postoperative 2 weeks (P < 0.05), but the expression of fibronectin had no significant difference between the two groups (P > 0.05). In addition, there was a decline trend in the expression of integrin β1 and fibronectin atpostoperative 2, 4, 8 weeks. To conclude, the porous tantalum material is beneficial to enhance adhesion of osteoblasts on the surface and inside the micro-pores. Increased expression of integrin β1 and fibronectin on the tantalum-bone interface at early stage may promote early osteogenesis, while their decreased expression at bone maturing stage can promote osseointegration and bone remodeling.

BACKGROUND: Previous studies have demonstrated that the Chinese porous tantalum made in China has non-toxicity and good biocompatibility, which can promote osteogenesis. OBJECTIVE: To investigate the effects of transforming growth factor β1 on proliferation, cel cycle and secretion of osteoblasts on porous tantalum/MG63 osteoblast-like cel composites. METHODS: Passage 3 MG63 osteoblast-like cel suspension (1×109/L) was seeded onto the porous tantalum, then the cel composites were inoculated in the medium with 0, 0.5, 5 and 10 μg/L transforming growth factor β1, respectively. The proliferation of osteoblasts was detected by cel counting kit-8 assay at 1-13 days after inoculation; the cel morphology and ultrastructure observed by scanning electron microscope and transmission electron microscopy; and level of col agen type I detected by enzyme-linked immunosorbent assay. RESULTS AND CONCLUSON: 0.5, 5, 10 μg/L transforming growth factor β1 could promote the osteoblast proliferation, and cel proliferation in the 5 μg/L transforming growth factor β1 group was higher than that in the other groups; in the 5 μg/L transforming growth factor β1 group, laminated osteoblasts adhered on the surface and grew into inner of porous tantalum, which extended more pseudopodia toward the scaffold; osteoblasts-secreted matrix could cover the scaffold and numerous rough endoplasmic reticulum, free ribosomes, dense mitochondria, Golgi apparatus as wel as matrix vesicles could be found in the cytoplasm. In addition, the level of col agen type I in the 5 μg/L transforming growth factor β1 group was significantly higher than that in the other groups (P < 0.05). These results indicate that transforming growth factor β1 can promote proliferation, and col agen type I secretion of osteoblasts on porous tantalum/MG63 osteoblast-like cel composites, and the optimum mass concentration of transforming growth factor β1 is 5 μg/L.