Biomechanical properties of Achilles tendon in diabetic vs. non-diabetic patients

Structural and functional impairments of the Achilles tendon in diabetic patients has the potential to contribute to ulcer formation through altered foot mechanics. This study aimed to examine the biomechanical and histopathological alterations in Achilles tendon specimens from diabetic vs. non-diabetic individuals.

42 Achilles tendon samples obtained from patients treated with below-knee or above-knee amputation for chronic diabetic foot ulcers (n=21) or for non-diabetic conditions (n=21) were included. A tensile test was performed for each tendon and a stress vs. strain graft was obtained to calculate following biomechanical parameters: elasticity (Young modulus), load, stiffness, toughness, energy, strain, elongation and tenacity. Groups were also compared with regard to histopathological findings (inflammatory cell infiltration, collagen organization, and degeneration).

Non-diabetic tendons exhibited a superior biomechanical profile over diabetic tendons with regard to the following biochemical parameters: elasticity, maximum load, stiffness, toughness, load, energy, strain and elongation at break point, tenacity, and strain at automatic load drop (p<0.05 for all comparisons). Diabetic tendons had mild impairment of collagen organization and focal collagen degeneration, whereas neither diabetic nor non-diabetic tendons had inflammatory cell infiltration.

The structural and functional alterations associated with diabetes adversely affect the biomechanical properties of the Achilles tendon, potentially acting together with neuropathy and ischemia in the development of diabetic foot ulcers.