It is widely known that bone density changes in people with diabetes. This may lead to fractures, and is proposed to leave individuals susceptible to Charcot neuroarthropathy. However, bone density cannot be accurately assessed using existing techniques. A new method has been proposed by a group of Australian researchers to measure bone density in the feet of people with diabetes. Alex Barwick and colleagues from the University of Newcastle have investigated the reliability of using computed tomography (CT) as a new method to estimate bone density measurements.
The feet of ten people with diabetes were scanned twice on the same day, and the bone density of both trabecular (also known as ‘cancellous bone’, the more spongy part of the bone) and cortical bone (the hard exterior of bones) were assessed on both scans. Excellent agreement was found for trabecular bone, but the findings for the cortical bone were less promising. Some agreement was found in the larger bones (talus, calcaneus, navicular, cuboid and first metatarsal), but not in the cuneiform or other metatarsalia.
As trabecular and cortical bone are metabolically different, separating them is important to better understand bone density and its relation to disease processes. For trabecular bone, this new method shows promise. For cortical bone, it is unclear if the lower reliability is a result of the method used to obtain the density, or whether it is related to the nature of the cortical bone. To estimate cortical bone density, three regions were selected from each CT slide and averaged, as the whole cortical bone could not be captured. For trabecular bone, only one region needed to be selected. It is likely that this selection process negatively impacted the reliability. This will be optimized with more research.
The current findings are not yet applicable in daily clinical practice, but they are another step forward in better understanding of bone density and Charcot neuroarthropathy in people with diabetes. Reliable methods are needed to study the intricacies of bone density before actual bone breakdown, especially when they are relatively simple and quick. This Australian research is a start to further develop such methods.