This is caused by the mechanical pinching or compression of soft tissue structures as they pass through the subacromial space at the tip of the shoulder. The subacromial space is formed by the humeral head as the base, and the acromion as the roof. The main structures affected are the rotator cuff tendons (usually supraspinatus), the subacromial bursa (a fluid filled sac which aims to reduce friction and improve glide between tendons) and the long head of bicep.
Impingement syndrome is caused by a narrowing of the subacromial space. This may be due to inflammation of tendons, the bursa, or less commonly, via invasion of bony spurs due to osteoarthritis.
The condition may be instigated with movement placing excessive strain on the rotator cuffs and bursa, such as those above head. Occasionally, symptoms may precede a traumatic episode such as a fall on an outstretched arm.
In athletes, shoulder impingement is often seen in weight lifters, swimmers or tennis players and commonly predisposed by a muscular imbalance creating protracted shoulders and posture.
The condition tends to cause fairly substantial pain at the top of the shoulder and can radiate down the outside of the arm to as far as the elbow. Most frequently, the pain is noted when the arm is elevated or above the head, so movement such as changing gear in the car, brushing hair or teeth, weight lifting or throwing, can cause aggravation. Patients may also experience night and morning pain, or discomfort when lying on affected side.
Rotator cuff strain
The rotator cuff complex consists of four muscles which work together to provide movement and stability to the gleno-humeral joint (shoulder). The muscles assist in elevation of the arm away from the body and internal and external rotation of the arm at the shoulder. Rotator cuff injuries are likely to occur for specific reason, this may be due to lifting or pulling of a heavy object in a jerking motion, following a traumatic fall, or repetition of the same shoulder movement i.e. weight lifting, swimming.
Patients may describe a sudden pain or a tearing sensation during the initial provocative activity. Following this, a diffuse ache may be noted which can radiate to the neck, back and arm. Weakness may be observed and sharp pain when lifting or carrying objects may be present.
The technical and medical term for frozen shoulder is ‘adhesive capsulitis’. True frozen shoulder* can be an extremely painful condition which causes the shoulder to become completely or partially restricted in movement. The symptoms tend to progress and then improve over three phases. Literature would suggest that the average duration of each phase is around 6 months.
Stage 1: freezing stage. Stage 2: Frozen stage. Stage 3: thawing stage.
The condition is caused by inflammation and contraction of the capsule surrounding the shoulder joint. Ultimately this binds the joint down and reduces range of movement.
The exact understanding of which this condition occurs is unknown; however there is a marked association with diabetics, heart disease, dupuytrens contracture and history of a shoulder trauma/surgery.
*Frozen shoulder is commonly misdiagnosed without an appropriate orthopaedic examination
Acromioclavicular joint strain
This is a relatively common sports injury usually associated with a direct blow to the area or a fall onto the point of the shoulder, typically seen in rugby or cycling injuries. The Acromioclavicular joint, is the area where the clavicle (collar bone) meets with the bony protrusion from the scapular (shoulder blade). A strain of the joint is regarded as a connective tissue injury causing damage to the ligaments binding the joint together.
Patients tend to experience a very much localised pain at the tip of the shoulder immediately at the time of injury. The area can become red and swollen and often very tender to touch. Aggravating activities include, lying on the side of discomfort, using the arms above shoulder height, moving the arm across the body and all push and pull activity, i.e. press ups.
Severe injury may cause a deformity of the joint, whereby the bone separates and protrudes upwards. This can suggest a full or partial rupture of the supporting ligaments.
The bicep is responsible for flexion of the arm at the elbow and assisting with forwards elevation of the arm at the shoulder. When the bicep is contracted large stresses are placed on the long head attachment which inserts directly into the top of the shoulder at the superior glenoid fossa (part of the shoulder blade).
The condition is characterised as damage, inflammation and degeneration of the tendon and pain in the front of the shoulder. Common causes are due to overuse and repetitive or excessive demands causing damage to the bicep tendon. Other mechanisms of injury are due to a singular high force which the tendon is unable to manage, i.e. chest press, throwing injury.
Symptoms are often describes as a dull ache in the front of the shoulder which can cause a ‘catching sensation’ with certain movements. In particular, carrying heavy objects, throwing, night pain and activities where the arms are above shoulder height tend to aggravate symptoms.