How the clinical dosage of bone cement biomechanically affects adjacent vertebrae.

OBJECTIVE: This study evaluated the biomechanical changes in the adjacent vertebrae under a physiological load (500 N) when the clinically relevant amount of bone cement was injected into fractured cadaver vertebral bodies. METHODS: The embalmed cadaver thoracolumbar specimens in which each vertebral body (T12-L2) had a BMD of < 0.75 g/cm2 were used for the experiment. For establishing a fracture model, the upper one third of the L1 vertebra was performed wedge osteotomy and the superior endplate was kept complete. Stiffness of specimens was measured in different states. Strain of the adjacent vertebral body and intervertebral disc were measured in pre-fracture, post-fracture, and after augmentation by non-contact optical strain measurement system. RESULTS: The average amount of bone cement was 4.4 ml (3.8-5.0 ml). The stiffness of after augmentation was significantly higher than the stiffness of post-fracture (p < 0.05), but still lower than pre-fracture stiffness (p < 0.05). After augmentation, the adjacent upper vertebral strain showed no significant difference (p > 0.05) with pre-fracture, while the strain of adjacent lower vertebral body was significantly higher than that before fracture (p < 0.05). In flexion, T12/L1 intervertebral disc strain was significantly greater after augmentation than after the fracture (p < 0.05), but there was no significant difference from that before the fracture (p > 0.05); L1/2 vertebral strain after augmentation was significantly less than that after the fracture (p < 0.05), but there was no significant difference from that before the fracture (p > 0.05). CONCLUSIONS: PVP may therefore have partially reversed the abnormal strain state of adjacent vertebral bodies which was caused by fracture.

[Association of vitamin D receptor gene polymorphisms with susceptibility to bone and joint tuberculosis in Chinese Han population].

OBJECTIVE: To investigate the association between vitamin D receptor (VDR) gene Apa I polymorphism and the susceptibility to bone and joint tuberculosis in Chinese Han population. METHODS: Between May, 2015 and June, 2016, 100 patients with bone and joint tuberculosis and 100 healthy volunteers were recruited concomitantly in Heyuan Hospital of Traditional Chinese Medicine. Vitamin D receptor gene Apa I polymorphisms in these subjects were analyzed using SNaPshot. RESULT: The genotype frequencies of Apa I-AA, Apa I-Aa and Apa I-aa were 51%, 41%, and 8% in the case group and 33%, 55%, and 12% in the control group, respectively, showing significant differences between the two groups (P<0.05). The genotype of Apa I-AA was significantly higher in the case group with an odds ratio (OR) of 2.073 (95% CI: 1.142-3.763). CONCLUSION: The Apa I polymorphisms of the VDR gene are associated with the susceptibility to bone and joint tuberculosis in Chinese Han population, and individuals with a Apa I-AA genotype are at greater risks to develop bone and joint tuberculosis.