Introduction: Disorders of the shoulder are extremely common, with reports of prevalence ranging from 30% of people experiencing shoulder pain at some stage of their lives up to 50% of the population experiencing at least one episode of shoulder pain annually, and for people over 65 years of age shoulder pain is the most common musculoskeletal problem. In addition to the high incidence, shoulder dysfunction is often persistent and recurrent with 54% of sufferers reporting on-going symptoms after 3 years. To a large extent the substantial morbidity reflects (i) a current lack of understanding of the pathoaetiology, (ii) a lack of diagnostic accuracy in the assessment process, and (iii) inadequacies in current intervention techniques. Pathology of the rotator cuff and subacromial bursa are considered to be the principal cause of pain and symptoms arising from the shoulder. Diagnostic labels given to pathology arising in these structures includes; rotator cuff tendinopathy / tendinosis / tendinitis; supraspinatus tendinopathy / tendinosis / tendinitis, subacromial impingement syndrome, subacromial bursitis, bursal reaction, partial thickness, full thickness and massive rotator cuff tear. Generally these diagnostic labels relate more to a clinical hypothesis as to the underlying cause of the symptoms than definitive evidence of the histological basis for the diagnosis or the correlation between structural failure and symptoms. For the purposes of this paper the terms rotator cuff tendinopathy and subacromial impingement syndrome will be used to cover the spectrum of these soft tissue pathologies.