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Several clinical series, analyzing fracture healing in patients with diabetes mellitus (DM), demonstrated significant incidence of delayed union, non-union, and pseudarthrosis. In this study, analysis was performed to evaluate the effects of blood glucose (BG) control on fracture healing in the D M BB Wistar rat, a rat strain that represents a close homology to Type I DM in man. Our study showed decreased cell proliferation at the fracture site as well as decreased mechanical stiffness and bony content in the poorly controlled DM rats. To determine the effect of BG control, D M rats were treated with insulin sufficient to maintain physiologic BG levels throughout the course of the study. Values of cellular proliferation, biomechanical properties and callus bone content in tightly controlled DM animals were not significantly different from values of non-DM control values. This study suggests that insulin treatment with resultant improved BG control will ameliorate the impaired early and late parameters of D M fracture healing.

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Type I diabetes mellitus (DM) is associated with impaired fracture healing. Specifically, DM affects multiple phases of fracture healing including early cellular proliferation and late phases resulting in inferior biomechanical properties. Recent studies demonstrated the utility of pulsed low-intensity ultrasound (US) to facilitate fracture healing. The current study evaluated the effects of daily application of US on mid-diaphyseal femoral fractures in DM and non-DM BB Wistar rats. Immunohistochemical staining for PCNA was used to evaluate cellular proliferation at 2, 4, and 7 days post-fracture. In concordance with previous findings, DM fracture callus demonstrated decreased cellular proliferation. Importantly, the application of US did not significantly alter the proliferation in either DM or control groups. However, mechanical testing revealed significantly greater torque to failure and stiffness in US-treated DM versus non-US-treated DM groups at six weeks post-fracture. Despite the inability of US to affect the early proliferative phase of fracture healing, its application clearly results in improved mechanical properties during the late phases of healing. These findings suggest a potential role of US as an adjunct for DM fracture treatment.

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