A subacromial injection is a common medical procedure that delivers medication directly into the subacromial space of the shoulder. It aims to alleviate pain and reduce inflammation. The subacromial space sits beneath the acromion, a bony part of the shoulder blade, and above the rotator cuff tendons and bursa. The injection helps manage discomfort and improve shoulder function.
Conditions Treated by the Injection
Subacromial injections treat several inflammatory shoulder conditions. One frequent reason is shoulder impingement syndrome, where the rotator cuff tendons or the subacromial bursa become pinched and irritated as they pass through the narrow subacromial space, often during overhead arm movements. This mechanical compression leads to pain and restricted motion.
Subacromial bursitis is another common condition, involving inflammation of the bursa. The bursa cushions the shoulder joint and facilitates smooth movement. Overuse, repetitive activities, or minor trauma can cause the bursa to swell, resulting in sharp pain with movement and often night pain. Rotator cuff tendinopathy, or tendinitis, also benefits from these injections. This involves irritation, damage, or wear to the rotator cuff tendons, causing swelling and pain in the shoulder and upper arm.
The Injection Procedure
The subacromial injection procedure involves careful preparation. Patients are seated with their shoulder exposed. The skin over the shoulder is cleaned with an antiseptic solution.
A local anesthetic, such as lidocaine, may numb the skin. A needle is then carefully guided into the subacromial space. Ultrasound guidance is often used to visualize internal structures and confirm precise needle placement. Once positioned, a mixture of medication, commonly a corticosteroid and a numbing agent, is slowly injected.
Post-Injection Care and Recovery
After a subacromial injection, protect the treated shoulder. Rest the shoulder for 24 to 48 hours, avoiding heavy lifting or strenuous activities. Immediate relief from the numbing agent is temporary, lasting only a few hours.
A temporary increase in pain, known as a “steroid flare,” can occur within the first 24 to 48 hours. This normal reaction can be managed with ice packs, acetaminophen, or nonsteroidal anti-inflammatory drugs (NSAIDs). Full pain relief from the corticosteroid is noticeable within two to seven days, with maximum relief often achieved within one to two weeks. Following up with physical therapy is often recommended to strengthen muscles and improve shoulder function.
Potential Side Effects and Considerations
Subacromial injections are generally safe, but patients should be aware of potential side effects. Common mild reactions include temporary soreness, bruising, or increased pain at the injection site. Some individuals might experience temporary skin discoloration or dimpling.
Less common risks include very rare infection. There is also a small risk of tendon weakening or damage from repeated injections. To minimize this risk, healthcare providers limit injection frequency, often recommending no more than three to four injections per year in the same shoulder, with at least three months between injections. Patients with diabetes should monitor blood sugar levels, as corticosteroids can cause temporary elevations.