The subacromial bursa is a small, fluid-filled sac located in the shoulder joint. Its primary role is to reduce friction between various structures within this complex anatomical area.
Anatomy and Function
The subacromial bursa is located beneath the acromion, a bony projection of the shoulder blade. It lies directly above the rotator cuff tendons, forming a protective layer. This bursa is typically thin and small, containing a small amount of synovial fluid that resembles a lubricant.
The bursa’s main function is to facilitate smooth movement within the shoulder joint. It acts as a cushion, allowing rotator cuff tendons and muscles to glide effortlessly under the acromion during arm movements. This cushioning effect prevents friction and wear between bones and soft tissues, especially during overhead activities.
Common Conditions and Symptoms
The most common condition affecting this structure is subacromial bursitis, which involves inflammation of the bursa. When inflamed, the bursa can swell and become painful, hindering smooth motion. This inflammation often results in localized pain in the shoulder, frequently described as an ache on the top or outer side of the joint.
Pain associated with subacromial bursitis commonly worsens with movement, especially when lifting the arm overhead or reaching behind the back. Individuals might also experience tenderness when pressing on the affected shoulder area. Inflammation can lead to a limited range of motion or a sensation of weakness in the arm. Subacromial bursitis can manifest acutely, with a sudden onset, or become chronic, persisting for an extended period.
Causes and Risk Factors
Subacromial bursitis can develop from repetitive stress on the shoulder joint. Activities involving frequent overhead arm movements, such as painting, swimming, or throwing sports, can contribute to its onset. Continuous friction and pressure on the bursa from these activities can lead to irritation and inflammation. Direct trauma to the shoulder, like a fall or a direct impact, can also trigger bursitis.
Certain underlying medical conditions, including various forms of arthritis like rheumatoid arthritis or gout, may predispose individuals to bursal inflammation. Additionally, poor posture, muscle imbalances around the shoulder, or the presence of bone spurs can irritate the bursa, increasing the likelihood of developing this condition.
Diagnosis and Treatment Approaches
Diagnosing subacromial bursitis typically begins with a physical examination. The doctor will assess the shoulder’s range of motion, identify areas of tenderness, and evaluate for weakness. A discussion about the patient’s symptoms and medical history also provides important diagnostic information.
Imaging tests, such as X-rays, might be ordered to rule out other conditions like bone spurs or arthritis. Magnetic resonance imaging (MRI) can provide detailed images of soft tissues, helping to confirm inflammation within the bursa.
Non-surgical treatment approaches are usually the first line of management. These often include rest from aggravating activities, applying ice to the affected area, and taking nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation. Physical therapy plays a significant role, focusing on exercises to improve shoulder strength, flexibility, and overall mechanics. In some cases, a corticosteroid injection directly into the bursa can provide substantial relief by reducing inflammation.
Surgical intervention for subacromial bursitis is uncommon and generally considered only for severe, persistent cases that do not respond to conservative treatments.