Published online Jul 18, 2013. doi: 10.5312/wjo.v4.i3.124
Revised: March 22, 2013
Accepted: May 9, 2013
Published online: July 18, 2013
AIM: To investigate the in vivo effects of type I diabetes on the mechanical strength of tibial bone in a rodent model.
METHODS: The biomechanical effect of diabetes on the structural integrity of the tibia in streptozotocin induced diabetic Wistar rats was analysed. Induction of diabetes was achieved by an intra-peritoneal injection and confirmed by measuring serial blood glucose levels (> 150 mg/dL). After 8 wk the tibiae were harvested and compared to a control group. Biomechanical analysis of harvested tibiae was performed using a three-point bending technique on a servo hydraulic MTS 858 MiniBionix frame. Maximum force applied to failure (N), stiffness (N × mm) and energy absorbed (N/mm) were recorded and plotted on load displacement curves. A displacement control loading mode of 1 mm/min was selected to simulate quasi-static loading conditions. Measurements from load-displacement curves were directly compared between groups.
RESULTS: Fourteen streptozotocin induced diabetic Wistar rats were compared against nineteen non-diabetic controls. An average increase of 155.2 g in body weight was observed in the control group compared with only 5 g in the diabetic group during the experimental study period. Levels of blood glucose increased to 440.25 mg/dL in the diabetic group compared to 116.62 mg/dL in the control group.The biomechanical results demonstrate a highly significant reduction in the maximum load to failure from 69.5 N to 58 N in diabetic group compared to control (P = 0.011). Energy absorption to fracture was reduced from 28.2 N in the control group to 23.5 N in the diabetic group (P = 0.082). No significant differences were observed between the groups for bending stiffness.
CONCLUSION: Streptozotocin-induced diabetes in rodents reduces the maximum force and energy absorption to failure of bone, suggesting a predisposition for fracture risk.
Core tip: The bones of streptozotocin-induced diabetic Wistar rats are more fragile with reduced toughness, characterized by a reduction in the capacity to absorb energy and with lower forces required to induce fracture in comparison to those in the control group. Our findings confirm previous studies and lend weight to the literature describing the detrimental relationship between the mechanical properties of bone subjected to diabetes mellitus. Further research needs to be conducted to ascertain whether uncontrolled diabetes in a human population affects the structural and biomechanical properties of bone.