The Copenhagen Cohort of Patients With Shoulder Pain: A Study Investigating Subacromial Impingement and Related Clinical Entities

1. Study design

Patients presenting with subacromial impingement syndrome (SIS) are subcategorized into clinical entities (section 6), including the entity 'isolated SI'. The distribution of patients within the different clinical entities is explored in study 1. Patients presenting with an entity other than isolated SI are treated in accordance with the preference of the treating shoulder surgeon. There is no formal follow-up of these patients within this project.

Patients with isolated SI are prescribed at least three months of structured physiotherapy, and the correlation between the treatment outcome and individual pathophysiological factors (section 4) are investigated (study 2). Patients who does not benefit satisfactorily from at least 3 months of structured physiotherapy and presents with prolonged symptoms (at least 6 months) are offered to participate in a randomized controlled trial investigating the difference in treatment outcome from glenohumeral arthroscopy and ASD compared to glenohumeral arthroscopy alone (study 3). All patients are diagnosed and treated by orthopedic shoulder surgeons. 2. Research questions and objectives

Study 1 1.31 Research question 1: Do patients with SIS constitute a heterogeneous group?

Objective 1: