ObjectiveTo explore the nature of micromovement and the biomechanical staging of fracture healing.MethodsThrough literature review and theoretical analysis, the difference in micromovement research was taken as the breakthrough point to try to provide a new understanding of the role of micromovement and the mechanical working mode in the process of fracture healing.ResultsThe process of fracture healing is the process of callus generation and connection. The micromovement is the key to start the growth of callus, and the total amount of callus should be matched with the size of the fracture space. The strain at the fracture end is the key to determine the callus connection. The strain that can be tolerated by different tissues in the fracture healing process will limit the micromovement. According to this, the fracture healing process can be divided into the initiation period, perfusion period, contradiction period, connection period, and physiological period, i.e., the biomechanical staging of fracture healing.ConclusionBiomechanical staging of fracture healing incorporates important mechanical parameters affecting fracture healing and introduces the concepts of time and space, which helps to understand the role of biomechanics, and its significance needs further clinical test and exploration.
Objective To investigate the effects of exogenous bone morphogenetic protein(BMP) and transforming growth factor-β(TGF-β) on biomechanical property for ulna of fracture healing.Methods Thirty-six adult rabbits were made the model of right ulnar fracture and treated locally with TGF-β/PLA, BMP/PLA，TGF-β+BMP/PLA or PLA(as control group). Fracture healing was evaluated by measurement of the mechanical parameters and geometric parameters.Results As compared with control group, the geometric parameters, the bending broken load, the ultimatebending strength, the bending elastic modulus, the ultimate flexural strength, the flexural elastic modulus, the ultimate compressing strength, the compressingelastic modulus, and the ultimate tensile strength for ulna of fracture healingincreased significantly in the treatment groups(P＜0.01). These parameters were higher in TGF-β+BMP/PLA group than in TGF-β/PLA group or in BMP/PLA group andin TGF-β/PLA group than in BMP/PLA group(P＜0.05). There was no significant difference in bone density between the treatment groups and control group. Conclusion Local application of exogenous TGF-β and BMP canincrease the callus formation and enhance biomechanical strength of bone after fracture healing. A combination of TGF-β and BMP has synergetic effect in enhancing fracture healing.
OBJECTIVE To investigate the feasibility of osteoid callus allograft as a kind of bone healing promoting materials. METHODS The osteoid callus was obtained at one week after bilateral femoral fracture of a SD rat, then was kept at -196 C for 2 weeks. The bone defect model which bone repair was in intra-membranous osteogenesis was made at bilateral tibial shaft in 5 rats, and filled with the osteoid callus in the left defect area, the right side was filled with allogenous cancellous as control group. The specimen were processed with undecalcified technique and the sections were staining with light blue and sofranin T. RESULTS After 2 weeks, there were cartilage and bone formation in the defect area of osteoid callus graft group(3/4), medullary cavity formation in bone tissue with cartilage arround it, fibrous tissues between new bone and host bone. While there were no cartilage or bone formation in the control group. CONCLUSION The allograft osteoid callus is not absorbed by immunological rejection, but changed into bone tissue through endochondral osteogenesis. It is inspiring to develop osteoid callus allograft as a kind of material for bone healing.
Objective To investigate the relationship between the tibia callus diameter ratio(CDR) and prognosis during tibial distraction and the occurrenceof late deformity or fracture. Methods We measured tibiallengthening callus diameter and added up the cases of angular deformity and fracture in 68 casesfrom January 1996 to December 2001, to calculated callus diameter ratios and compare the relationship between the tibia callus diameter during tibial distraction and the occurrence of late callus angular deformity or fracture. Results In 23 cases of CDRlt;80%, 13 cases had new bone fracture, 21 cases had angular deformity gt;5 degree. In 6 cases of 81%lt;CDRlt;85%, there were 4 cases of angular deformity gt;5 degree. In the other 39 cases of CDRgt;85%, there were no fracture and angular deformity. Conclusion When the CDR was gt;85%, there wereno angular deformity and fracture, but when the CDR was lt;80%, the complications of fracture and angular deformity occur. CDR is a better alarming index for preventing the complications occurring in tibial lengthening.