Mechanical and chemical properties of rotator cuff tendons

Shoulder disease is the third most common musculoskeletal problem, and rotator cuff tendon tears account for the greatest proportion of shoulder complaints. Rotator cuff tears are estimated to affect between 5-30% of adults, with higher incidences of tearing and fa ilure to heal in elderly patients, placing a huge socioeconomic burden on an ageing British population. Serious concern arises as a large proportion of technically correct surgical repairs re-rupture. The intra-articular environment of the tendon often precludes nonnal healing and surgical repair is often necessary to improve pain and restore some function. It is feasible that there may be an inherent phys iological or biomechanical defect in the tissue that prevents complete heal ing without some further augmentation to the surgical repair. Improved understanding of the biochemical and biomechanical changes in tom rotator cuff tendons may help to reduce the high rerupture rates. This study aimed to characterise nonnal, and different sized rotator cuff tendon tears from small samples obtained intraoperatively to try to use tests that may potentially be clinica lly usefu l in the future. Tendon samples were mechanically tested using dynamic shear analysis, a fonn of rheology, to overcome gripping and slippage problems of very small specimens. It was found that tom tendons had a significandy reduced storage modulus compared to normal tendons, particularly for massive tears. Chemical analysis of tendons using Fourier transform infrared spectroscopy revealed that partial and different sized rotator cuff tendon tears are chemically distinguishable. The onset of rotator cuff tear pathology is mainly due to an alteration of the collagen structural arrangements, with associated changes in lipids and carbohydrates. Collagen structural changes in small and massive tendons were quantified us ing differential scanning calorimetry, which allows measurement of coHagen thermal properties as a reflection of their structural integrity. Small and massive tendon tears had reduced thermal properties and hence reduced collagen integrity when compared to normal tendons, although there was no difference between the two tear groups. Gene expression differences between the small, massive tears and normal tendons were studied using microarray analysis, and revealed that the different groups were biologically distinguishable.EThOS - Electronic Theses Online ServiceGBUnited Kingdo