Comparative Study Of Decompression Osteoporosis Of Rabbit Humerus After Denervation And Braking

Objective: The changes of biomechanical properties and bone mineral density of humerus in rabbits after denervation and braking were compared and analyzed.Methods: Fifty-four New Zealand rabbits were randomly divided into normal group,denervated group and braking group,each group was given three sampling time points of 4 weeks,8 weeks and 12 weeks.There were 18 rabbits in each group and 6 rabbits at each time point.In the denervated group,the brachial plexus of the right upper limb was completely severed.In the braking group,the right upper limb was firmly fixed by plaster and plaster bracket.MAIN OUTCOME MEASURES: At 4,8 and 12 weeks after modeling,the right humerus of rabbits was taken out for examination,the wet weight of the whole humerus was weighed,the mechanical properties of the humerus were measured by three-point bending test,the bone mineral density was measured by dual-energy X-ray absorptiometry,and the fine structure of bone tissue was observed by HE staining.Results: BMD in denervated group and brake group was lower than that in normal group at the same time(P < 0.05).The BMD of humerus in denervated group was lower than that in brake group,but the difference was not statistically significant(P > 0.05).Compared with the braking group,the maximum load and bending strength of the denervated group were lower than those of the braking group at all time points after modeling,but the difference was significant only at the 12 th week(P < 0.05).The wet weight of humerus in the denervation and braking groups decreased with time.However,there was no significant difference in wet weight of humerus between denervated group and braking group(P > 0.05).Compared with bone histomorphology of normal group,bone trabeculae became thinner in denervated group and braking group,and there were obvious fracture between trabeculae,and a large number of vacuolar structures.Conclusions: Denervation and braking can cause severe osteoporosis.In terms of the degree of osteoporosis caused by both,denervation has a more serious effect on the mechanical properties of bone than braking.Lower mechanical load plays a more important role in the process of osteoporosis.