The shoulder is made up of 3 bones, the humerus (upper arm bone), the scapula (shoulder blade) and the clavicle (collar bone). The shoulder joint (also known as the Glenohumeral Joint) is a ball and socket joint formed by the head of the humerus, which is the ball, and the glenoid fossa of the scapula, which is the socket.
The shoulder joint is the most mobile joint in the body and is held stable by an important group of muscles called the Rotator Cuff, comprising of the Supraspinatus, Infraspinatus, Teres Minor and Subscapularis muscle. These muscles form tendons that attach to the head of the humerus to actively keep the shoulder joint centred on the glenoid fossa. Covering the surface of the tendons is a bursa (fluid-filled sac), which helps to lubricate the shoulder and allow smooth movement of the humeral head under the acromion (end bit of the clavicle).
Certain factors can increase the risk of shoulder impingement. When there is muscle imbalance around the shoulder or if there is a bone spur under the acromion, the bursa and/or tendons can get pinched between the humeral head and the acromion, causing shoulder impingement.
Individuals who have to do a lot of overhead activities (eg throwers, painters, repetitive lifting work) are more prone to this condition. Shoulder impingement causes inflammation of the bursa (bursitis) and/or tendon (tendinopathy/tendonitis) and pain may occur at rest or during arm movements (painful arc when lifting arm up or when having to hold arm at shoulder height). Sometimes, the pain radiates down the upper arm. There may also be tenderness and localised swelling in the shoulder.
The management of shoulder impingement depends on the cause of the problem. Your physiotherapist will assess you to find out the causes of your shoulder impingement and may request for imaging to assist in diagnosis. If the cause(s) is modifiable with conservative management, they will use various techniques to minimise pain and inflammation, restore shoulder range and importantly, help you target muscle imbalances which contribute to your symptoms.
In some cases where a bony abnormality or structural issues within the shoulder joint which is causing the impingement or if symptoms persist despite a period of conservative treatment, you may require a referral to a doctor or an Orthopaedic specialist for further management (such as steroid injections or arthroscopic surgery).