THE NATIVE TENSILE-STRENGTH OF THE SUPRAS PINATUS TENDON - A BIOMECHANICAL STUDY

The traumatic tear of the rotator cuff has been discussed very intensi vely for a long time despite the fact that there do not exist represen tative objective data about the native tensile strength of these tendo ns. The aim of this study was to evaluate the age related native stren gth of the supraspinatus tendon. 25 fresh frozen cadaver specimen (age : 23-94, 24 h post mortem, 18 male, 7 female) were tested using so cal led cryojaws for soft tissue fixation. The results showed the major pa rt of the tensile forces to be transmitted through the anterior thicke r 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 st iffness of the supraspinatus tendon decrease with age. However, a 65 y ear old specimen still demonstrates a weight bearing structure (about 900 N maximum tensile strength) and is not necessarily ruptured or deg eneratively altered.