The rotator cuff is made up of 4 muscles which help you lift your arm when required. However, when you lift your arm, the space between your rotator cuff and the acromion is reduced which increases the pressure, and can lead to an impingement of your shoulder.

• Repetitive movements or overuse: repetitive movement of a joint can result in irritation or injury, leading to swelling and irritation. In an enclosed or narrow joint like the shoulders, swelling can cause compression of the muscles of the rotator cuffs, which may lead to the acromion to rub or impinge on the rotator cuffs, causing pain. In turn, this results in more swelling, more pressure and compression, and more pain. 
• Bursitis: swollen or inflamed bursa (fluid-filled space between your tendons and acromion) can cause the compression of the rotator cuff against the acromion, resulting in pain.
• Bone spurs: bony projections or edges that poke out from your bone can press up/impinge against your rotator cuff and cause pain. This can happen due to old age or may be congenital.

Symptoms include:

• Pain when you lift your arm
• Pain or discomfort at the front of your shoulder
• Pain at the side of your arm
• Pain when lying on the affected side
• Pain that worsens at night
• Pain when you reach behind your back
• Loss of muscle strength

Shoulder impingement can occur in conjunction with other shoulder injuries or problems such as shoulder bursitis, shoulder tendonitis, or rotator cuff tears. 

Therefore, it is important to seek advice from an orthopaedic specialist if you are experiencing any shoulder pain, so you can get a proper diagnosis and treatment. 

• Hobbies or occupations: activities such as swimming, baseball, softball, tennis, painting, moving boxes, lifting weights, and construction work can result in overuse or injury.
• Congenital: some individuals may be born with an acromion that is not straight, making it more prone to impinging on the rotator cuff.
• Age: as we age, we may develop bone spurs which can impinge on the rotator cuff.
• Previous shoulder injury: shoulder injuries can cause misalignment or chronic swelling of the area around the rotator cuff, increasing your risk of a shoulder impingement.

• Physical examination: your medical history will be obtained and your shoulder will be examined for areas of tenderness. Your orthopaedic specialist will also check your range of motion and shoulder strength.
• X-rays: an x-ray will be performed to check for the possibility of arthritis or bone spurs.
• Magnetic resonance imaging (MRI)/computed tomography scan (CT-scan): an MRI or CT-scan will be used to identify any rotator cuff or other related injury.

These are the treatment options available:

• Physiotherapy: physiotherapy is usually the first line of treatment for shoulder impingement. Gentle exercises can help to improve your strength and range of motion.
• Medication: painkillers and anti-inflammatory non-steroidal drugs (NSAIDs) medication can help alleviate pain and reduce inflammation as you heal.
• Corticosteroid injections: corticosteroid injections helps to reduce inflammation of the bursa due to bursitis.
• Arthroscopic surgery: surgical procedure known as arthroscopic surgery that is used to diagnose shoulder joint issues, works by inserting a small camera into your shoulder joint to examine and treat the area if necessary.