Diabetes mellitus impairs tendon-bone healing after rotator cuff repair
Bedi, A.; Fox, A. J.; Harris, P. E.; Deng, X. H.; Ying, L.; Warren, R. F.; Rodeo, S. A. J Shoulder Elbow Surg. 2010;19(7):978-988.
This study came out in the fall and won the Neer Award (the award for excellence in shoulder research) given by the Journal of Shoulder and Elbow Surgery. Several studies in the past have identified the association of diabetes and delayed healing in bone and skin, but this was the first study to demonstrate that diabetes also affects tendon healing. This study used a rat rotator cuff model to examine the affects of type I diabetes mellitus on rotator cuff tendon healing (48 rats total). One group had diabetes induced and the other served as the non-diabetic control. Both groups then underwent unilateral detachment of the supraspinatus tendon followed by immediate repair. At 1 and 2 weeks after surgery, tendon biomechanics and histology were assessed on the healing tendon. The tendons from diabetic rats had failed (ruptured) at lower loads and had abnormal collagen structure (a lack of parallel fibers). These changes demonstrate a significantly weak tendon attachment.

This is a very novel and interesting study demonstrating that diabetes plays a large role in rotator cuff tendon healing. Clinically rotator cuff tears occur frequently and the rate of re-tears is near 70%. With such a high failure rate type I diabetic patients need to be educated on proper glycemic control to minimize the risk for secondary injury and delayed healing. Although this study focused on type I diabetes, it is suggested that type II diabetes also produces similar effects. With type II diabetes at epidemic levels we need to also educate patients on proper exercise and nutrition that will help to eliminate hyperglycemia completely. In the case that an individual with diabetes does develop a rotator cuff tear we need to consider the delayed healing in our rehabilitation protocol. A more conservative rehabilitation protocol may be required to minimize the risk of retears. Specifically, longer durations of immobilization may help to improve tendon insertion site healing. Another novel approach that could be used to improve tendon healing in diabetic patients is the use of antioxidants. Several researchers believe that hyperglycemia causes oxidative stress and the use of antioxidants may reduce the deleterious affects of diabetes. Diabetes is clearly something that we need to be aware of and proper knowledge of current ongoing research will allow us to be better clinicians when it comes to treating diabetic patients.

Written by: Stephen Thomas
Reviewed by: Jeffrey Driban