[Achilles tendon rupture and achillodynia. The importance of tissue regeneration].

Ruptures of the Achilles tendon mainly occur in males aged 30 to 40 years; in an analysis of 561 specimens taken from ruptured tendons only 25% were classified as degenerative tendopathy. Ultrastructural studies of areas in and near the tendon rupture and of specimens of tendonitis show more collagen fibres with small diameter in comparison to normal samples. These morphological changes correspond to structures of tendon tissue after reversible damage of rabbit tendons. Test models were throttling of the Arteria poplitea or Arteria femoralis, sheathing of the Achilles tendon and deflecting the tendon in order to increase the tension. The electrophoretic determination of collagen showed increasing type III collagen with formation of repair tissue. First of all the experimental findings as well as the clinical fact of rare secondary ruptures after operatively treated ruptures of Achilles tendons prove good conditions for tendon repair. But probably an increasing number of small diameter collagen fibres and changings in the pattern of collagen types weaken the mechanical properties of the tendon.