Skeletal Disorders: Subacromial Impingement Syndrome

Pain is the main symptom of deterioration and damage to the surrounding tissue where the sensation arises. This unpleasant sensory and emotional distress is determined by the region and systems of the body involved, and is categorized into degrees of pain by the intensity, time of pain onset and aetiology (1, 2). Pain is a subjective sensation and it is therefore the patients´ own perception that describes and categorizes the level. If the duration of pain exceeds 3 months it is commonly known as chronic pain or longstanding pain, which is a major complaint in the general population with musculoskeletal disorders (MSDs). In the general population, MSDs have a prevalence of approximately 16% which ranks shoulder pain as the third most prevalent MSD after knee- and back pain (3).
The incidence of shoulder pain has been estimated to be 11,2 per 1000 per year in the primary care-system, with varying causes 41% of individuals with upper-limb pain show persistent symptoms after one year (4, 5).
In a
He was the first to introduce the term “subacromial impingement syndrome” (SIS) to describe the condition, emphasizing the mechanical stress of the rotator cuff tendons under the acromial arch. Neer argued that all the impingement lesions and 95% of rotator cuff pathology are caused by friction between the acromion and surrounding tissue within the subacromial region(10, 11), since the most common symptoms include pain during shoulder- and overarm elevation. This hypothesis has later been challenged and it has been proven hard to find evidence supporting the theory for a purely mechanical aetiology for chronic shoulder pain. Other findings that suggest that the aetiology of SIS is