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Objective: To investigate the effect and mechanism of fracture healing brachial plexus injury. Upper limb fracture with brachial plexus injury is very common in orthopedics. Fracture healing is a complex biological process, being affected by many factors, and peripheral nerve tissue plays an important role in the regulation of fracture healing, a large number of experimental and clinical data to prove, peripheral nerve nutritional and metabolic status of bone tissue The major impact is achieved through the neuropeptide, in addition to the autonomic vasomotor control will affect the bone blood flow. So when the fracture with peripheral nerve injury, should be actively early nerve repair in order to restore its role in the regulation of fracture healing. But its specific mechanism of action is not clear, so early after peripheral nerve injury repair fractures become the hot spot of research work. In this study, contrast rabbit pure radial fracture and brachial plexus injury accompanied by two sets of radial fracture model, at different times from the X-ray, biomechanics, bone mineral density, staining to observe the difference. Analysis of the mechanism of action of peripheral nerve injury on fracture healing, to provide experimental basis for further guidance on clinical. Methods: 60 healthy, mature New Zealand White rabbits, rabbits aged 12 to 15 months, weighing 4.0 to 4.5kg. All experimental rabbits were randomly divided into two groups: nerve damage and fracture group (experimental group), simple fractures nerve injury group (control group). Experimental group was unified under sterile conditions in the rabbit right arm armpit incision of the skin and subcutaneous tissue to expose the brachial plexus, isolated proximal transverse cut brachial plexus in the the brachial plexus dry parts, and cut 0.5 cm length, layered together every wound. Experimental group and the control group in the middle of the right forearm of Rabbits radial side cut the skin and subcutaneous tissue, revealing radial wire saw here interrupted by transverse radial, with a fine wire fracture of the distal and proximal radius and ulna were fixed in layered together every wound. Plaster immobilization. Postoperative The experimental animals were placed in the cage, animal breeding selection criteria feed unified feeding, pay attention to insulation, prevention of wound infection. , Respectively, after the first 2 weeks, 4 weeks, 6 weeks line radiological examination, observation of fracture healing and the amount of callus. Then underwent the dual-energy X-ray absorptiometry to measure bone mineral density, were after 2 weeks, 4 weeks, 6 weeks of randomly selected 10 the line air embolism were killed, cut along the middle of the right forearm radial side of the original incision approach skin, exposed radial fracture site, carefully remove the bone specimens, the naked eye callus growth and fracture healing. Removal of attached muscles around the fracture site, bone specimens for biomechanical test measured the bending strength limit measure callus strength at maximum load. Then instantly callus drawn, ready to slice preparation for histological analysis, evaluation of fracture healing and quality of callus. Collating data for statistical analysis, and conclusions. Results: after 2 weeks, 4 weeks, 6 weeks, X-ray examination, after the success of anesthesia, shooting right forearm is the lateral view. The results showed that: after 2 weeks, you can see that the experimental group, a relatively large number of callus, while the control group callus; 4 weeks, the experimental group than the control group the amount of callus, but the callus loose callus no significant law; 6 weeks, the experimental group callus was excessive growth, uneven density, while the control group callus density is uniform, the callus appropriate. Subsequently, using dual-energy X-ray absorptiometry to measure bone mineral density of fracture healing segment. Two sets of fractures bone mineral density increased with the extension of the date after. Two sets of bone mineral density difference was not statistically significant (p gt; 0.05) at 2 weeks postoperatively. After 4 weeks, 6 weeks, two groups of bone mineral density difference was statistically significant (p lt; 0.05) (Note: BMD with the ratio of the normal side). Biomechanical testing of bone specimens, two weeks after surgery, the maximum load of the experimental group (10.10 ± 2.52), the maximum load of the control group (11.86 ± 2.45) was not statistically significant (p GT; 0.05); postoperative weeks, the maximum load of the experimental group (12.63 ± 2.42), the maximum load of the control group (15.98 ± 2.30), a statistically significant difference (p lt; 0.05); 6 weeks after surgery, the maximum load of the experimental group (43.57 ± 3.52), the maximum load of the control group (50.12 ± 4.31), a statistically significant difference (p lt; 0.05) The specimens for histological observation by light microscopy at 2 weeks postoperatively, the experimental group osteotylus growth sparse, low density, arranged disorder that the osteoid more, the callus obviously immature, and can see a large number of osteoclast cells ; denser callus of the control group, Sunwise line arrangement, osteoid less in some places visible external callus bridge rendezvous. After 4 weeks and 6 weeks experimental group callus more but relatively sparse, narrow trabecular bone, osteoid thicker, more osteoclasts; the control group callus dense, the trabecular wide, dense trabecular bone between the gap narrowing. Conclusion: In the process of fracture healing peripheral nervous system plays a very important role. Proved brachial plexus injury, the radial distribution of fracture healing process callus growth rate and quality are very much affected. 2 the one hand, the peripheral nervous system can be adjusted to the number and activity of osteoblasts and osteoclasts in order to achieve a balance, on the other hand can promote calcium phosphate deposition, promoting bone mineralization, bone callus maturation, so that the normal trabecular reconstruction, along the lines of force are arranged. 3 after peripheral nerve injury, the impact on fracture healing may be associated with neuropeptide. Neuropeptide promote the healing of soft tissue around the fracture to accelerate fracture healing, can also be directly involved in the healing process of the fracture. Some neuropeptide the vascular regulatory activity by regulating the blood vessels to dilate and vascular permeability, thereby affecting the blood supply directly affect fracture healing. Neuropeptides can also stimulate pain receptors play a pain, fractures brake protective effect. Denervation can cause the fractures partial formation of a large number of defective callus. Normal innervation is necessary for fracture healing, clinical encountered peripheral nerve injury and fracture, should be actively early repair of damaged nerves.
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