ABSTRACT
BACKGROUND:Bioglass has good biocompatibility and biological activity, which can be combined with calcium phosphate bone cement to form an absorbable bioglass that has the advantages of both materials and is expected to have a better use of space. OBJECTIVE:To explore the mechamism of the new type of absorbable bioglass injection for vertebral body supporting and osteogenic induction in osteoporosis rats. METHODS:Twenty-seven female Sprague-Dawley rats were selected to make osteoporosis models by bilateral ovariectomy, and after 1 month, the rats were randomized into three groups. Bone defect models were established in the lumbar L4 segment of al the rats. Rats in the experimental group were subjected to absorbable bioglass injection; rats in the control group 1 underwent polymethylmethacrylate bone cement injection; and rats in the control group 2 were given injectable calcium phosphate. Twelve weeks after implantation, the compressive strength, degradation and osteogenesis of the implant materials were detected, and levels of serum bone morphogenetic protein-2 and transforming growth factor-β were measured. RESULTSAND CONCLUSION: The compressive strength, hydroxyapatite deposition amount, and weight loss ratio in the experimental group were significantly higher than those in the two control groups (P < 0.05); the relative volume, thickness and number of bone trabeculae in the experimental group were significantly higher than those in the control groups (P < 0.05); the bone morphogenetic protein-2 and transforming growth factor-β protein levels in the experimental group were significantly higher than those in the two control groups (P < 0.05). These findings indicate that the new-type absorbable bioglass can greatly strengthen the vertebral body supporting and promote osteogenic effect in osteoporosis by enhancing the bone morphogenetic protein-2 and transforming growth factor-β protein levels.
ABSTRACT
BACKGROUND:Bony and structural feature often cause pulout strength decrease of pedicle screw, which induces loosening and pulout, and finaly results in fixation failure. Thus, it is very important to elevate the stability of pedicle screw. OBJECTIVE:To detect the biomechanical stability of bone cement injectable canulated pedicle screw, and to provide reference for bone cement dosage. METHODS: We selected T11-L4 samples of seven fresh adult corpses, containing 40 vertebral bodies. They were randomly divided into bone cement injectable canulated pedicle screw group and DTPSTM pedicle screw group (n=20). After screw implantation, 1, 2, 3 and 5 mL bone cement was injected. The diffuse distribution of bone cement was observed by imaging. The maximum axial pulout strength was measured. RESULTS AND CONCLUSION:When the dose of bone cement was 1-3 mL, the average maximum axial pulout strength was significantly greater in the bone cement injectable canulated pedicle screw group than in the DTPSTM pedicle screw group (P 0.05). The regression equation was Y=25.269X+133.681 (R2=0.837) in the bone cement injectable canulated pedicle screw, and Y=32.039X+99.251 (R2=0.936) in the DTPSTM pedicle screw group. When the dosage of bone cement was 1-5 mL, the maximum axial pulout strength was highly positively correlated with bone cement dosage (|R| > 0.8). These results suggested that bone cement augmentation pedicle screw could apparently elevate the stability of the screw. The maximum axial pulout strength of the pedicle screw was positively correlated with bone cement dosage. After reaching the satisfactory fixation effects, the bone cement injectable canulated pedicle screw can reduce bone cement dosage, diminish the risk of bone cement leakage, and have more advantages than DTPSTM pedicle screw.
ABSTRACT
Objective To analyze the etiology and features of Pilon fractures and to explore their best operative method.Methods 92patients with pilon fracture were treated operatively and followed up between1991and 2001.According to the Ovadi a -Beals' s classification,there were 7cases of Type I fracture,12of II,30of III,26of IV,17of V.During the o peration,55patients had limited in ternal fixation with calcaneal trac-tion,18with calcaneal traction and plaster splint,10with tibial and fi bula internal fixation,9with external fixation apparatus.Results92patients were followed up for an av erage time of 53months(ranging from 4～103months).According to Mazur ' s criteria,the results of the treatm ent were rated as excellent in 42patients,good in 34,fair in 11and poor in 5.Conclusion The pilon fracture is caused by both t he force of falling from a high altitude and the force of rebounding which act in the distal end of tibia an d fibula.Limited internal fixation with calcaneal traction is a right choice of operative method to treat pilon fr actures.[