RESUMEN
Objective To study the bone biomechanics of the rabbit osteoporosis models induced by dexamethasone sodium phosphate injection (DX) using a combined treatment modality of 99Tc-MDP and GuKangLing.Methods Rabbits were intramuscularly injected with DX (2 mg/kg) twice a week for 6 weeks.The animal osteoporosis model group (Group C) and normal group (Group A) were compared to confirm the model was available.Another control group (Group B),the osteoporosis control group (Group D) were set for the comparison at the end of the experiment.The 99Tc-MDP therapy group (Group E),GuKangLing therapy group (Group F) and 99Tc-MDP plus GuKangLing therapy group (Group G) were included in the study.The treatment lasted for 16 weeks.The bone biomechanics,cytopathology bone histomorphology,bone mineral density (BMD),X-ray,CT,bone scintigraphy and serum bone alkaline phosphatase (BALP)and P (bone gla protein) were chosen as the markers or methods to evaluate the treatment results (excellent,effective and invalid).The analysis of variance (ANOVA) and t-test were used for group comparison analysis.Results Cytopathology result indicated that there was no bone trabecula destruction in Group A.However,there was distinct bone destruction in Group C.The bone biomechanics (left femur head (265.914 ±52.773) N,L4(369.671 ±94.919) N),BMD(left femur (0.238 ±0.016) g/cm2,L4(0.236 ±0.016) g/cm2)and bone histomorphology ( (66.230 ± 10.848) ％ ) in Group C reduced clearly as compared with Group A ((405.343±55.410) N,(750.870±53.718) N,(0.294±0.017) g/cm2,(0.302±0.023) g/cm2,( 131.500 ± 21.846) ％ ) ( t ≥4.550,all P ＜ 0.01 ).Radionuclide bone scan also showed that the uptake of tracers was higher by the main arthrosis in Group C than that in Group A.Vertebra was not clearly visualized on bone scan image.There were significant differences between Group A and Group C in serum BALP and P ((45.000±7.303) vs (12.485 ±1.512) U/L,(0.168±0.018) vs (0.115 ±0.017) μg/L,t =4.126,5.476,both P ＜ 0.01 ),which indicated that the animal osteoporosis model was available.The pathological results showed an improved recovery of bone structure and trabecular in Groups E and G,but a worse recovery in Group F.Biomechanics result in Groups E and G (left femur head (386.457 ±77.077) N and (432.771 ± 17.525) N,L4(649.550 ± 126.859) N and (655.443 ±76.555) N) improved apparently,which were similar to Group B.The radiotracer uptake in Group F was lower than that in group D.The bone biomechanics,bone histomorphology,BMD,serum BALP and P after the treatment showed significant differences in Groups E,F and G (F:8.556 - 31.608,all P＜0.01 ),and the bone biomechanics result in Group G was a little better than that in Group E (t =2.625,P ＜ 0.05 ).The results of Group G and E were considered as excellent,and Group F was considered as effective.Conclusions The treatment of 99Tc-MDP combined with GuKangLing could improve the bone biomechanics of rabbit osteoporosis models and may be a potential method to increase the bone strength for resisting external force.