BACKGROUND: Whole body vibration which is used to prevent and treat osteoporosis recently is uncomfortable due to its strong vibration strength. The designed compound vibration with low vibration strength could effectively prevent bone quality decrease of ovariectomized rats. OBJECTIVE: To verify the effect of compound vibration with low vibration strength on the bone quality of ovariectomized rats. METHODS: A total of 32 4-month-old female SD rats were used in this study. All SD rats were randomly dlvided into 4 groups: normal control group, ovadectomized control group, vibration Ⅰ group (45 Hz-55 Hz, 0.05 g-0.1 g), and vibration Ⅱ group (45 Hz-55 Hz, 0.12 g-0.21 g), with8 rats for each group. The intervention to each vibration group was onea day, 20 minutes/tlmes and 5 days per week. The resting interval was shorted than 2 days, and the whole vibration intervention lasted 13 weeks. Bone mineral density (BMD) before and after vibration, ex vivo bone microstructure parameters and biomechanics parameters ware measured in this study. RESULTS AND CONCLUSION: Lumbar BMD of ovariectomized control group was decreased (P < 0.05), but the BMD in the normal control group and the two vibration groups was increased significantly. Femoral BMD of all groups was increased, but there was no significant difference among the four groups. Bone microstructure parameters of the three ovariectomized groups ware decreased; however, parameters including number, thickness and distance of bone trabecula and bone volume fraction in the vibration Ⅱ group were significantly improved compared to ovadactomized control group. Moreover, bone strength of lumbar vertebra in the two vibration groups was significantly increased (P=0.025, 0.006), but there was no significant difference compared to normal control group. Compound vibration with low strength could effectively prevent BMD decrease of ovadectomized rats, lighten the dagrea of bone microstructure damage, keep bone strength, improve bone quality of ovadectomized rats, and potentially prevent osteoporosis.

Objective: To investigate reliability and short-term effectiveness of axis laminar screws for reducible atlantoaxial dislocation (RAAD). Methods: A clinical data of 41 patients with RAAD who were admitted between February 2013 and February 2018 and met the inclusion criteria was retrospectively analyzed. The atlases in all patients were fixated by lateral mass screws, and the axes were fixed by laminar screws in 13 cases (LS group) and by pedicle screws in 28 cases (PS group). There was no significant difference in gender, age, and preoperative Japanese Orthopedic Association (JOA) score between the two groups ( P>0.05). The effectiveness was estimated by post-operative JOA score; and the accuracy of the axis screw, atlantoaxial bone graft fusion, and the fixation stability were examined by X-ray film and CT. Results: All incisions healed by first intention. All patients were followed up 12-17 months (mean, 13.8 months) in LS group and 12-20 months (mean 14.1 months) in PS group, and the difference in follow-up time was not significant ( Z=-0.704, P=0.482). At last follow-up, JOA scores were 13.9±1.6 in LS group and 14.3±1.8 in PS group, which significantly improved when compared with the pre-operative scores in the two groups ( t=-9.033, P=0.000; t=-15.835, P=0.000); while no significant difference was found between the two groups ( t=-0.630, P=0.532). Twenty-five screws of 26 screws in LS group and 54 screws of 56 screws in PS group were implanted accurately, with no significant difference in the accuracy of the axis screw between the two groups ( Z=-0.061, P=0.951). All patients obtained atlantoaxial bone graft fusion, except 1 case in PS group. There was no significant difference in the atlantoaxial bone graft fusion between the two groups ( Z=-0.681, P=0.496). Conclusion: For RAAD, Axis laminar screws can maintain the atlantoaxial primary stability and had a good short-term effectiveness. So, it could be an alternative and reliable technique for axis screw.

Objective:To explore the feasibility and clinical efficacy of gelatin sponge packing in reducing bone cement leakage in percutaneous kyphoplasty (PKP).Methods:A retrospective case-control study was conducted in data of 171 patients (171 vertebrae) with monosegmental lumbar osteoporosis compressive fracture treated by PKP from January 2015 to December 2018 in Sichuan Orthopedic Hospital. There were 66 males and 105 females, with the age of (67.9±6.7)years (range, 60-87 years). There were 22 patients with T 10 fracture, 28 with T 11 fracture, 37 with T 12 fracture, 34 with L 1 fracture, 32 with L 2 fracture and 18 with L 3 fracture. A total of 80 patients were pre-filled with gelatin sponge before injection (Group A), and 91 patients were not filled with gelatin sponge before injection (Group B). The operation time, amount of bone cement, and rate of bone cement leakage were recorded. The change of anterior vertebral height, Cobb angle, visual simulation score (VAS) and Oswestry disability index (ODI) were compared before operation and at postoperative 1 day, 3 months, 6 months, 12 months. Results:All patients were followed up for 1-12 months [(12.8±0.6)months]. The operation time in Group A and B was (48.3±1.2)minutes and (42.3±1.3)minutes ( P<0.05). The amount of bone cement in Group A and B was (5.4±0.8)ml and (5.6±0.7)ml ( P>0.05). The incidence of bone cement leakage in Group A and B was 11% (9/80) and 26% (24/91) ( P<0.05). There was no significant difference between the two groups in the anterior height of injured vertebrae, change of Cobb angle, VAS and ODI before and after operation ( P>0.05). Conclusion:Gelatin sponge can reduce the rate of bone cement leakage in PKP for the treatment of thoracolumbar osteoporosis compressive fracture, and has similar effect with PKP in correcting kyphosis, alleviating pain and improving life quality.

Objective:To investigate the feasibility of establishing a canine model of lumbar intervertebral disc degeneration through the application of cumulative axial load and a six-phase combined motion on the vertical sitting dog's lumbar spine.Methods:Twenty adult female grass dogs, each weighing 10.0±0.5 kg, were randomly divided into two groups, with 10 dogs in each group. In the model group, dogs were secured to an exercise machine in a vertical position, and six phases of lumbar spine movement (flexion and extension, left and right lateral flexion, left and right rotation, 45° each) were combined with a specific number of cycles under continuous axial load (245 N). In the control group, dogs were secured to the exercise machine in a vertical position without any intervention. Radiographic examinations were performed before and after 20,000, 50,000, 100,000, and 150,000 compound exercises in the model group. The disc height index (DHI) was measured through lateral X-ray, and MRI T2-mapping was used for quantitative analysis of intervertebral disc degeneration. When intervertebral disc degeneration was evident on MRI T2-weighted imaging (modified Pfirrmann system > Grade V), the combined motion was halted. Micro-CT quantitative analysis of bone mineral density (BMD) in the upper and lower endplates, trabecular bone structure, and histological staining (HE staining, "O" staining, Sirius red staining) were employed to verify and assess the degree of intervertebral disc degeneration.Results:After 50,000 compound exercises, mild degeneration of the intervertebral discs at L 6-7 and L 7S 1 was observed on T2-weighted imaging. With the accumulation of exercise load, the degree of degeneration progressively increased, reaching a moderate degree of degeneration after 100,000 composite exercises, and DHI began to decrease. Mild degeneration was also observed in the upper L 5-6 intervertebral disc. When the cumulative exercise volume reached 150,000 repetitions, the height of intervertebral spaces in the L 5-6, L 6-7, and L 7S 1 segments further decreased, and the intervertebral discs exhibited severe degeneration (improved Pfirrmann grading system Grades IV-VI). The upper L 4-5 intervertebral discs also displayed mild degeneration. Histological scores were as follows: L 5-6 (8.2±0.8), L 6-7 (9.5±0.7), and L 7S 1 (10.3±0.5), indicating a degree of degeneration in the order of L 5-6