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[Incorporation of cortical allograft: a biomechanical study]
1Department of Orthopaedics, Ninth People's Hospital, Shanghai Second Medical University, Shanghai 200011.
Objective:
To explore the changes of biomechanical properties of cortical allograft in different mechanical environments.
Method:
Cortical allograft was transplanted to each side of the midshaft diaphyseal ulnar of 40 rabbits. The left transplanted allograft underwent normal physiological load, while the right underwent lower load. Animals were killed and specimens taken for examination of bone mineral density, bone porosity and maximal three-point-bend breaking load.
Result:
The union strength of allograft-host bone junction increased constantly, while the internal creeping substitution led to an initial greater weakening of the cortical allograft itself and the later recovery of its strength. In comparison, the union strength of the normally loaded graft-host surface was significantly higher than that of the lower loaded side at eight and sixteen weeks after transplantation. At the sixteenth week, there was greater bone strength in normally loaded graft than that in less loaded graft.
Conclusion:
The internal repair would lead to initial greater weakening of cortical allograft and the later gradual recovery of its strength. The effect of physiological load can accelerate the improvement of the biomechanical properties of allograft.