A subacromial injection is a frequent, minimally invasive approach to managing shoulder discomfort and inflammation. The procedure involves delivering medication directly into the subacromial space, a narrow area within the shoulder joint. This targeted delivery allows a high concentration of therapeutic agents to reach the specific source of pain. The goal of this localized treatment is to reduce swelling, alleviate pain, and ultimately improve the mobility and function of the shoulder.
Conditions Treated by the Injection
The subacromial space is situated beneath the acromion, the bony tip of the shoulder blade. This space contains the subacromial bursa, a fluid-filled sac, and the rotator cuff tendons, which are susceptible to friction and inflammation. Irritation in this confined space leads to significant pain and restricted arm movement.
The injection primarily treats subacromial bursitis (inflammation of the bursa sac) and shoulder impingement syndrome. Impingement occurs when rotator cuff tendons become pinched between the acromion and the upper arm bone (humerus). This mechanical pinching causes irritation and swelling that the injection is designed to resolve.
The procedure also addresses rotator cuff tendinopathy and inflammation associated with frozen shoulder (adhesive capsulitis). Physicians consider the injection when conservative measures, such as rest, anti-inflammatory medications, and physical therapy, have not provided lasting relief. Targeting the inflammation directly provides the necessary pain reduction to allow a patient to fully engage in rehabilitative exercises.
The Injection Procedure
The medical professional first positions the patient, usually seated or lying down, to ensure the shoulder is relaxed and accessible. The skin around the injection site is then cleansed with an antiseptic solution. A topical cold spray or local anesthetic may be used to numb the skin, making the needle insertion more comfortable.
The injection solution combines a corticosteroid, such as triamcinolone, for potent anti-inflammatory effects that reduce swelling over days to weeks. This is paired with a local anesthetic, such as lidocaine, which provides immediate, temporary pain relief. This dual approach allows patients to experience rapid comfort while the long-term anti-inflammatory agent begins its work.
To ensure precise placement into the narrow subacromial space, the physician often uses imaging guidance, such as ultrasound or fluoroscopy. This real-time visualization confirms the needle’s position, significantly improving the accuracy of the injection. Once the needle is correctly situated, the medication is slowly injected, and the patient may feel a sensation of pressure. The entire process is typically completed in under five minutes, after which a small dressing is applied.
Recovery and Potential Side Effects
Patients should limit activity involving the injected shoulder for the next 24 to 48 hours. Although immediate relief may be felt due to the anesthetic, this effect is short-lived and usually fades within a few hours. This initial period of rest helps the medication settle in the subacromial space and prevents undue stress on the treated tissues.
It is common for some patients to experience a temporary increase in pain, referred to as a “steroid flare,” which can last up to two days. This temporary discomfort is typically managed with ice packs and over-the-counter pain relievers, and it does not indicate a problem with the injection itself. Full pain reduction from the corticosteroid usually becomes noticeable within two to seven days as the inflammation begins to subside.
The injection is intended to be a therapeutic tool, not a standalone cure. Patients are often encouraged to begin gentle range-of-motion exercises within a day or two to capitalize on the reduced pain. Potential side effects are rare but include infection at the injection site or, with multiple injections, localized skin changes like discoloration or thinning of the subcutaneous fat. Patients with diabetes must monitor their blood sugar closely, as the corticosteroid can cause a temporary elevation in glucose levels for a few days following the procedure.