Strains of human rotator cuff tendons at various joint positions : a cadaveric study

Abstract

Rotator cuff tears can cause significant shoulder disability. While there are many factors thought to be responsible for the initiation and progression of tears, biomechanical factors such as strains are also significant. The purpose of this study was to detect the bursal-side human rotator cuff strains over a range of clinically relevant joint positions. With the help of Differential Variable Reluctance Transducers , bursal-side rotator cuff strains were analyzed in cadaveric shoulder-specimens at 0 degree, 15 degree, 30 degree, 45 degree, 60 degree and 85 degree of the glenohumeral abduction in the scapular, coronal and sagittal plane. It was observed that joint positions had a pronounced effect on the tendon's strain. At the scapular and coronal plane, the strain at anterior edge of the supraspinatus was more than that of the posterior edge during elevation. This explains the common observation that supraspinatus tear is normally on the anterior edge. For elevation in the sagittal plane, the strain at the posterior edge was more than that of the anterior portion of the supraspinatus. This explains that there is a strain gradient between the anterior and posterior portion of the supraspinatus at all planes.