Joint & Soft Tissue Injection
Therapeutic indications include the delivery of local anesthetics for pain relief and the delivery of corticosteroids for suppression of inflammation. Side effects are few, but may include tendon rupture, infection, steroid flare, hypopigmentation, and soft tissue atrophy. Injection technique requires knowledge of anatomy of the targeted area and a thorough understanding of the agents used. In this overview, the indications, contraindications, potential side effects, timing, proper technique, necessary materials, pharmaceuticals used and their actions, and post-procedure care of patients are presented.
Injection of joints, bursae, tendon sheaths, and soft tissues of the human body is a useful diagnostic and therapeutic skill for family physicians. With training, physicians can incorporate joint and soft tissue injection into daily practice, yielding many benefits. For example, a lidocaine (Xylocaine) injection into the subacromial space can help in the diagnosis of shoulder impingement syndromes, and the injection of corticosteroids into the subacromial space can be a useful therapeutic technique for subacromial impingement syndromes and rotator cuff tendinopathies. Evidence-based reviews of joint and soft tissue injection procedures have found few studies that support or refute the efficacy of common joint interventions in medical practice.1–3 However, substantial practice-based experience supports the effectiveness of joint and soft tissue injection for many common problems.
Postinjection Instructions and Care
An adhesive dressing should be applied to the injection site. To minimize pain and inflammation after leaving the office, the patient should be advised to apply ice to the injection site (for no longer than 15 minutes at a time, once or twice per hour), and non-steroidal anti-inflammatory agents may be used, especially for the first 24 to 48 hours. The affected area should be rested from strenuous activity for several days after the injection because of the small possibility of local tissue tears secondary to temporarily high concentrations of steroid. This risk lessens as the steroid dissipates. Patients should be educated to look for signs of infection including erythema, warmth, or swelling at the site of injection, or systemic signs including fever and chills. The patient should keep the injection site clean and may bathe.
Steps for Injection and Joint Aspiration
When possible, the patient should be placed in the supine position. This will help prevent or mitigate the effects of a vasovagal or syncopal episode. Palpate the soft tissue or bony landmarks. Follow the steps for site preparation. For soft tissue injections, the following modalities may be used for short-term partial anesthesia: applying ice to the skin for five to 10 minutes; applying topical vapo-coolant spray; or firmly pinching the skin for three to four seconds at the injecting site.12 Once the skin is anesthetized, the needle should be inserted through the skin to the site of injection. To prevent complications, adhere to sterile technique for all joint injections; know the location of the needle and underlying anatomy; avoid neuromuscular bundles; avoid injecting corticosteroids into the skin and subcutaneous fat; and always aspirate before injecting to prevent intravascular injection.
The injection should flow easily and should not be uncomfortable to the patient. Most pain is the result of tissue stretching and can be mitigated by injecting slowly. If there is strong resistance while injecting, the needle may be intramuscular, intratendinous, or up against bone or cartilage, and it should be repositioned.
The entry point for injection or aspiration should be identified. The point of entry can be marked with an impression from a thumb-nail, a needle cap, or an indelible ink pen. The important goal is to minimize risk of infection at the site. Prepare the area with an alcohol or povidone-iodine (Betadine) wipe. For all intra-articular injections, sterile technique should be used.