Differential scanning calorimetric examination of ruptured lower limb tendons in human

The tendon ruptures are serious injuries of the lover limb in middle age and physically active population. While the Achilles tendon rupture is common, the patellar ligament and quadriceps ligament ruptures are an absolutely rare injury. Usually there is no correlation between the velocity of the trauma and the supervening of the rupture. The aetiology of the degenerative changes in the collagen structures of the tendons and ligaments which could be disposed for the rupture are still not clear. Our hypothesis was that before the injury there are clear pathological abnormalities in the tissues of the tendons, which are predisposed for the rupture, and could be monitored besides the classical histological methods by differential scanning calorimetry. The thermal denaturation of human samples was monitored by a SETARAM Micro DSC-II calorimeter. All the experiments were performed between 0 and 100 °C. The heating rate was 0.3 K/min. DSC scans clearly demonstrated significant differences between the control and ruptured samples (control: T m = 59.7 °C, T 1/2 = 1.4 °C and Δ H cal = 8.54 J/g; ruptured Achilles tendon: T m = 62.75 °C, T 1/2 = 2.6 °C and Δ H cal = 1.54 J/g, ruptured Quadriceps tendon: T m = 64.8 °C, T 1/2 = 1.6 °C and Δ H cal = 1.53 J/g, ruptured Patellar tendon: T m = 63.9 °C, T 1/2 = 1.41 °C and Δ H cal = 0.97 J/g). These observations could be explained with the structural alterations caused by the biochemical processes. With our investigations we could demonstrate that DSC is a useful and well applicable method for the investigation of collagen tissue of the degenerated human tendons and ligaments. We can prove with this method that the degenerative changes of the tissue elements increase the thermal stability of collagen tissues of the tendons which could be disposed for the rupture.