Metabolic disorders are among known risk factors for tendinopathies or spontaneous tendon ruptures. However, the underlying cellular and molecular mechanisms remain unclear. We have previously shown that human and rat tendon cells produce and secrete insulin upon glucose stimulation. Therefore, we hypothesize that nutritional glucose uptake affects tendon healing in a rat model. Unilateral full-thickness Achilles tendon defects were created in 60 female rats. Animals were randomly assigned to three groups receiving different diets for 2 weeks (high glucose diet, low glucose/high fat diet, control diet). Gait analysis was performed at three time points (n=20/group). In addition, tendon thickness, biomechanical (n=14/group), and histological and immunohistochemical analysis was conducted. Subsequently, a subtractive-suppression-hybridization (SSH) screen comparing cDNA pools (n=5) prepared from repair tissues of the high glucose and the control diet group was conducted to identify differentially expressed genes.Introduction
Materials and Methods
The medial periosteal hinge plays a key role in fractures of the head of the humerus, offering mechanical support during and after reduction and maintaining perfusion of the head by the vessels in the posteromedial periosteum. We have investigated the biomechanical properties of the medial periosteum in fractures of the proximal humerus using a standard model in 20 fresh-frozen cadaver specimens comparable in age, gender and bone mineral density. After creating the fracture, we displaced the humeral head medial or lateral to the shaft with controlled force until complete disruption of the posteromedial periosteum was recorded. As the quality of periosteum might be affected by age and bone quality, the results were correlated with the age and the local bone mineral density of the specimens measured with quantitative CT. Periosteal rupture started at a mean displacement of 2.96 mm ( The mean bone mineral density was 0.111 g/cm3 ( This study showed that the posteromedial hinge is a mechanical structure capable of providing support for percutaneous reduction and stabilisation of a fracture by ligamentotaxis. Periosteal rupture started at a mean of about 3 mm and was completed by a mean displacement of just under 35 mm. The microvascular situation of the rupturing periosteum cannot be investigated with the current model.
