The biomechanical and histological effects of diabetes on tendon healing: experimental study in rats

The aim of this study was to investigate the biomechanical and histological perspectives of healing of Achilles tendon in diabetic rats and compare the results with non-diabetic subjects. Fifty four adult Wistar Albino rats weighing 300-350 g were used throughout the study. Six animals were excluded from the study and replaced. Rats were randomly assigned to either the experimental or the control group comprised of 24 rats in each. Diabetes was induced in experimental group with streptozotocin. 3 days after the induction of diabetes, both Achilles tendons were transected 5 mm proximal to their insertions to the calcaneal bone and repaired by using 6/0 polypropylene sutures with modified Kessler method. At weeks 2, 4 and 6, eight rats from each group were euthanized. Left Achilles tendons including the repair site were prepared for histological evaluation and right legs were prepared for mechanical testing. When compared to control group, diabetic animals displayed a lower peak force for failure in each of the second, fourth and sixth week. The differences between the groups in each week were found to be significant in statistical assessments (p < 0.05). Histologic assessment revealed that the diabetic animals had significantly less amount of fibroblast proliferation and lymphocyte infiltration compared to the control group. There is significant delay in tendon strength at the end of week 2, 4 and 6 postoperatively in the diabetic rats. Therefore diabetic individuals require specific postoperative follow up and rehabilitation procedures.