Alterations of cartilage and collagen expression during fracture healing in experimental diabetes

We investigated alterations in the expression of mRNA for type II and type X collagen in fracture callus of experimentally induced diabetic animals co mpared with controls and performed radiographic, histological, immunocytoch emical and biomechanical studies. Experimentally induced diabetic rats exhibited an alteration in the tempora l expression of type II and type X collagen mRNA and a decrease in type X m RNA expression as compared to controls, Radiographs showed a more intense p eriosteal reaction and a more rapid reconstitution of cortices in control v ersus diabetic animals. Histologically there was a delay in chondrocyte mat uration and hypertrophy seen in diabetics, Immunolocalization of type X col lagen demonstrated a delay in type X collagen expression around the hypertr ophic chondrocytes. Biomechanical analysis showed a decrease in the strengt h of healing fractures in diabetic animals. Fracture healing in diabetic patients is compromised and may lead to delays in bone union. Though the exact mechanisms are unknown, we present evidenc e of decreased mechanical strength of the fracture and suggest that associa ted changes in collagen expression and chondrocyte maturation are mechanism s leading to delayed healing in untreated and poorly controlled diabetes.