High-resolution peripheral quantitative computed tomographic imaging of cortical and trabecular bone microarchitecture in patients with type 2 diabetes mellitus

Abstract

Context: Cross-sectional epidemiological studies have found that patients with type 2 diabetes mellitus (T2DM) have a higher incidence of certain fragility fractures despite normal or elevated bone mineral density (BMD).

Objective: In this study, high-resolution peripheral quantitative computed tomography was applied to characterize cortical and trabecular microarchitecture and biomechanics in the peripheral skeleton of female patients with T2DM.

Design and setting: A cross-sectional study was conducted in patients with T2DM recruited from a diabetic outpatient clinic.

Participants: Elderly female patients (age, 62.9 ± 7.7 yr) with a history of T2DM (n = 19) and age- and height-matched controls (n = 19) were recruited.

Outcome measures: Subjects were imaged using high-resolution peripheral quantitative computed tomography at the distal radius and tibia. Quantitative measures of volumetric (BMD), cross-sectional geometry, trabecular and cortical microarchitecture were calculated. Additionally, compressive mechanical properties were determined by micro-finite element analysis.

Results: Compared to the controls, the T2DM cohort had 10% higher trabecular volumetric BMD (P < 0.05) adjacent to the cortex and higher trabecular thickness in the tibia (13.8%; P < 0.05). Cortical porosity differences alone were consistent with impaired bone strength and were significant in the radius (>+50%; P < 0.05), whereas pore volume approached significance in the tibia (+118%; P = 0.1).

Conclusion: The results of this pilot investigation provide a potential explanation for the inability of standard BMD measures to explain the elevated fracture incidence in patients with T2DM. The findings suggest that T2DM may be associated with impaired resistance to bending loads due to inefficient redistribution of bone mass, characterized by loss of intracortical bone offset by an elevation in trabecular bone density.

Figure 1

Representative scout radiographs for the radius (A) and tibia (B) illustrating the localization for the tomographic acquisition (filled green).

Figure 2

Two-dimensional illustration of the segmented compartments included in the quantitative image analysis of the radius (A) and tibia (B): cortical bone (black), peripheral trabecular bone (dark gray), and medullary trabecular bone (light gray).

Figure 3

Median (by total vBMD) HR-pQCT images of the distal radius from CTRL (top), T2DM (middle), and T2DM with fracture (bottom): distal-most slices (A, E, I); proximal-most slices (B, F, J); 3D visualization of the mineralized bone structure (C, G, K); and 3D visualization of cortical bone (transparent gray) and Ct.Po. (solid green) (D, H, L).

Figure 4

Median (by total vBMD) HR-pQCT images of the distal tibia from CTRL (top), T2DM (middle), and T2DM with fracture (bottom): distal-most slices (A, E, I); proximal-most slices (B, F, J); 3D visualization of the mineralized bone structure (C, G, K); and 3D visualization of cortical bone (transparent gray) and Ct.Po (solid green) (D, H, L).

Figure 5

HR-pQCT images illustrating arterial calcifications in the distal radius (A) and distal tibia (B) of a subject with T2DM and a history of lower extremity fragility fracture.