SHOULDER INSTABILITY CAUSED BY ROTATOR CUFF LESIONS - AN IN-VITRO STUDY

Although many clinical and experimental studies have been published on shoulder instability, little is known about the relationship between degenerative changes of the cranial part of the rotator cuff and shoul der instability. The fact that some cuff lesions cause few symptoms an d do not progress, while others are not only incapacitating but also p rogress to massive ruptures and cuff arthropathy, is still not well un derstood. In this study the motion patterns of the intact joint, and c hanges induced by a division of the supraspinatus tendon alone or of t he supra- and infraspinatus tendons, were investigated in cadaver spec imens. The results demonstrate that a one tendon lesion does not influ ence the motion pattern, whereas a two tendon lesion induces significa nt changes compatible with instability of the glenohumeral joint.