Effect of type 2 diabetes mellitus on the microstructural, compositional and mechanical properties of cartilages

Background: Osteoarthritis (OA) is a chronic and complicated degenerative disorder of joints, including several phenotypes. Type 2 diabetes mellitus (T2DM) is one of the major causes of OA. However, few studies on the mechanical behavior of diabetic cartilages have been conducted. Methods: This study evaluated the microstructural, compositional, and mechanical properties of healthy and diabetic rat cartilages using scanning electronic microscopy, X-ray energy spectroscopy, histology staining, and microindentation tests. Results: Our results indicated that the diabetic cartilages had a significantly higher elastic modulus and similar permeability (95%CI: 3.72–8.56 MPa and 3.16×10⁻⁶–1.83×10⁻⁵ mm⁴/N·s) compared to the healthy cartilages (95%CI: 0.741–3.58 MPa and 3.15×10⁻⁶–1.14×10⁻⁵ mm⁴/N·s). Their stress relaxation behaviors were similar regardless of the loading rate except for the stretching parameter under the fast loading. Furthermore, the stress relaxation behaviors of the diabetic cartilages were significantly affected by the loading rate, especially the equilibrium force ratio and time constant. These mechanical outcomes could be attributed to the increase of fibril diameters and calcium aggregation in the cartilage. Conclusions: This study deepens our understanding of how T2DM might facilitate OA in cartilages, which could contribute to the development of more scientific diagnosis and therapies for patients with diabetes.