Changes in the mechanical properties of patellar tendon preparations of spontaneously diabetic dogs under long-term insulin therapy.

Diabetes mellitus is known to involve a wide range of musculoskeletal disorders including tendon contracture, tenosynovitis, joint stiffness, and osteoporosis. Recent studies with experimentally induced models of diabetes show that insulin therapy mitigates such alterations. These data are from relatively short-term experiments. This manuscript reports the results of tensile failure experiments on the canine patella-patellar tendon-tibia complex from a group of juvenile diabetic animals that received insulin therapy. The duration of the disease was 4-9 yr. The stiffness of the diabetic preparations in a physiological range of loading was approximately 13% greater than controls (P < 0.05). On the other hand, the strength of the tendon preparation from the diabetic population was not different from controls, but the mode of structural failure for controls was by substance and avulsion fractures while the diabetics failed by tensile fracture of the patella.