Relationships among neuropathies, vascular reactivity and bone in the diabetic foot (#334)
Neuropathies are common complications of diabetes and are proposed to influence peripheral bone principally via an altered vascular supply. This study aimed to determine the relationship between subtypes of neuropathy and vascular reactivity on foot bone density in people with diabetes. A case-control observational design was utilised with two groups: those with diabetic peripheral large fibre neuropathy (n=23) and a control group with diabetes but without neuropathy (n=23). Bone density in 12 foot bones was determined with computed tomography scanning. Neuropathy was assessed with standard clinical assessment. Additionally, post-occlusive reactive hyperaemia, presence of small fibre neuropathy and heart rate variability was determined. T-tests were used to determine differences in bone density between groups with and without neuropathy and hierarchical regression was used to examine the influence of small fibre neuropathy, heart rate variability and reactive hyperaemia on bone density. No difference in foot bone density was found between those with and those without large fibre neuropathy. Furthermore, no association between heart rate variability or reactive hyperaemia and bone density was found. Small fibre neuropathy was associated with increased cuboid trabecular bone density (p=0.006) with its presence predictive of 14% of the variance. This study found no clear association between presence of diabetic neuropathies and foot bone density. Furthermore, vascular reactivity appears to have no impact on bone density. This is despite the common assertion that diabetic neuropathy changes the blood supply to bone, reducing its density and predisposing it to fracture and Charcot foot.