title: A biomechanical investigation on the incorporation of cortical allograft in rabbit ulna defects.
abstract: OBJECTIVE: To explore the changes of biomechanic al properties of cortical allograft in different mechanical environments. METHODS: Cortical allograft was transplanted to each side of th e midshaft diaphyseal ulna of each one of 40 rabbits. The left transplanted allo graft underwent normal physiological load, while the right one underwent lower l oad. After animals were killed,specimens were taken for examination of bone mine ral density, bone porosity and maximal three-point-bend breaking load. RESULTS: The union strength of allograft-host bone junction wa s increased constantly; meanwhile, the internal creeping substitution led to an initial greater weakening of the cortical allograft itself and a later recovery of its strength. In comparison, the union strength of the normally loaded graft -host bone construct was significantly higher than that of the lower loaded sid e at the 8th and 16th week after transplantation. At the 16th week, there was gr eater bone strength in normally loaded graft than that in lower loaded graft. CONCLUSIONS: The internal repair can lead to initial greater we akening of cortical allograft and later gradual recovery of its strength. The ef fect of physiological load can accelerate the improvement of the biomechanical p rope rties of allograft.
authors.affiliation: Department of Orthopaedics, 9th People's Hospital, Shanghai Second Medical University, Shanghai 200011, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Tang
authors.forename: Kerong
authors.initials: K
authors.lastname: Dai
authors.forename: Wendong
authors.initials: W
authors.lastname: Xue