[Tensile strength of the tendon of the supraspinatus muscle in the human. A biomechanical study].

The traumatic tear of the rotator cuff has been discussed very intensively for a long time despite the fact that there do not exist representative objective data about the native tensile strength of these tendons. The aim of this study was to evaluate the age related native strength of the supraspinatus tendon. 25 fresh frozen cadaver specimen (age: 23-94, 24 h post mortem, 18 male, 7 female) were tested using so called cryojaws for soft tissue fixation. The results showed the major part of the tensile forces to be transmitted through the anterior thicker part of the tendon (e.g. 14 bony avulsions in this area). We found significant correlations between age and maximum strength (p < 0.001), age and stiffness of the tendon (p < 0.005) and stiffness and maximum strength (p < 0.001). These results show that tensile strength and stiffness of the supraspinatus tendon decrease with age. However, a 65 year old specimen still demonstrates a weight bearing structure (about 900 N maximum tensile strength) and is not necessarily ruptured or degeneratively altered.