Musculoskeletal manifestation in the joints of the diabetic animal model Otsuka Long-Evans Tokushima Fatty rat: A histological study

Diabetes mellitus (DM) is a chronic metabolic disease and is associated with vascular complications. However, the association of musculoskeletal manifestations and DM is not clear. We investigated musculoskeletal manifestations in the diabetic animal model Otsuka Long-Evans Tokushima Fatty (OLETF) rat. OLETF rats and control LETO (Long-Evans Tokushima Otsuka) rats at two different ages (44 and 95 weeks) were used. Knee joints and ankles with interphalangeal joints were removed, dissected, stained with hematoxylin and eosin (H&E), periodic acid-Schiff, methenamine silver, and Masson-trichrome staining and examined under light microscopy. Mild degenerative changes with focal edema and mild fibrosis were noted in OLETF rats (at 95 weeks of age) and in age-matched LETO rats, particularly in the interphalangeal joints. Necrosis, phagocytosis of necrotic fibers, regeneration, mononuclear inflammatory cell infiltration, granulation tissue, calcification and cartilage erosion were not observed in either the aged diabetic or the non-diabetic group. We found no prominent musculoskeletal manifestations in the OLETF rats. The reasons may be due to the low prevalence rate of these anomalies, or the life span of rats may be too short to express these alterations. More studies are needed to elucidate the pathophysiological mechanisms by demonstrating the musculoskeletal manifestations histologically.