Residency · Residency · Family Medicine
Joint and Soft Tissue Injections
Introduction
Joint and soft tissue injections are core procedural skills for family medicine physicians. When performed with proper technique and appropriate patient selection, corticosteroid injections provide effective pain relief for a variety of musculoskeletal conditions. This lecture covers indications, contraindications, technique, common injection sites, and post-procedure care.
Indications
Joint and soft tissue injections are appropriate for a range of musculoskeletal conditions. Inflammatory arthritis, including rheumatoid arthritis and crystal arthropathy flares from gout or pseudogout, responds well to intra-articular corticosteroid. Osteoarthritis, particularly of the knee, benefits from injection when oral therapies are inadequate. Bursitis at the subacromial, trochanteric, olecranon, or pes anserine bursae is a common indication. Tendinopathies such as lateral epicondylitis, de Quervain tenosynovitis, and trigger finger are frequently treated with injection. Adhesive capsulitis, plantar fasciitis, and carpal tunnel syndrome are additional targets. Joint aspiration serves both diagnostic purposes, to rule out septic arthritis or crystal disease, and therapeutic purposes in the setting of large effusions.
Contraindications
Absolute
Absolute contraindications include septic arthritis or overlying skin infection such as cellulitis, bacteremia, prosthetic joints (which should be deferred to orthopedics unless the clinician is experienced), and known hypersensitivity to the injectable corticosteroid or anesthetic.
Relative
Relative contraindications include coagulopathy or anticoagulation, though injection is generally safe with a therapeutic INR less than 3. Poorly controlled diabetes is a consideration because corticosteroids cause transient hyperglycemia lasting two to five days, and patients should be counseled and insulin doses adjusted accordingly. Direct injection into a tendon should be avoided due to the risk of rupture; the peritendinous sheath is the appropriate target. Fracture at the injection site is a relative contraindication. Multiple prior injections should prompt caution, with a general limit of three to four injections per joint per year and a minimum six-week interval between injections.
Injectable Agents
Corticosteroids
| Agent | Relative Potency | Duration of Action | Common Use |
|---|---|---|---|
| Triamcinolone acetonide | Intermediate | 2-6 weeks | Large joints, bursae |
| Methylprednisolone acetate | Intermediate | 2-6 weeks | Large and medium joints |
| Betamethasone | High | 2-4 weeks | Small joints, soft tissue |
| Dexamethasone | High | 1-3 weeks | Small joints, soft tissue (less tissue atrophy) |
Local Anesthetics
Lidocaine 1% has rapid onset within 1 to 2 minutes and a duration of 30 to 60 minutes; immediate pain relief after injection confirms accurate needle placement. Bupivacaine 0.25 to 0.5% has a slower onset of 5 to 10 minutes but provides 4 to 8 hours of relief. Either agent is often mixed with corticosteroid in the same syringe.
Other Injectables
Hyaluronic acid (viscosupplementation) is used for knee osteoarthritis, though evidence is mixed and guidelines vary on its recommendation. Platelet-rich plasma (PRP) has emerging evidence for tendinopathy and osteoarthritis but is not yet standard of care. Ketorolac offers an alternative to corticosteroid for patients who cannot receive steroids.
General Technique
Preparation
Informed consent should be obtained, including discussion of risks such as infection (1 in 10,000 to 50,000), post-injection flare, skin depigmentation, fat atrophy, tendon weakening, and transient hyperglycemia. The patient should be positioned comfortably with the target area accessible. Landmarks are identified by palpation, and ultrasound guidance should be considered for deep or difficult-to-access structures. The skin is cleaned with chlorhexidine or povidone-iodine and allowed to dry. Sterile gloves and a no-touch technique are used throughout.
Injection
The appropriate needle gauge and length depend on the target structure. Large joints such as the knee and shoulder require a 22-gauge, 1.5-inch needle. Small joints of the hand and wrist use a 25- to 27-gauge, 0.5- to 1-inch needle. Soft tissue targets such as trigger points and bursae use a 25-gauge, 1- to 1.5-inch needle. Aspiration before injecting confirms the needle is not in a vessel. When aspirating a joint effusion, a larger bore needle (18 to 20 gauge) should be used, and the fluid sent for cell count, crystal analysis, Gram stain, and culture. The injection should proceed slowly with minimal resistance, as high resistance suggests intratendinous placement and warrants repositioning the needle. Gentle pressure with gauze and a bandage completes the procedure.
Post-Procedure Care
Relative rest of the injected area for 24 to 48 hours is advised. Ice can be applied for 15 to 20 minutes as needed for post-injection discomfort. Patients should be warned about post-injection flare, which involves increased pain for 24 to 48 hours and occurs in up to 10% of patients. Diabetic patients should monitor glucose for two to five days. Return precautions include fever, increasing pain, redness, or swelling, which may indicate infection.
Common Injection Sites and Approaches
Knee (Intra-Articular)
The superolateral approach is performed with the patient supine and the knee extended; the needle is inserted 1 cm superior and 1 cm lateral to the superolateral patella and directed underneath the patella. The anterolateral or anteromedial approach is performed with the knee flexed 90 degrees, inserting at the joint line adjacent to the patellar tendon. A typical dose consists of 1 mL of triamcinolone 40 mg/mL mixed with 4 to 5 mL of lidocaine 1%.
Shoulder (Subacromial Bursa)
The posterior approach is performed with the patient seated and the arm relaxed; the posterolateral corner of the acromion is identified, and the needle is inserted 1 cm inferior and medial, directed anteriorly. The lateral approach inserts the needle below the lateral acromion edge, directing it medially under the acromion. A typical dose is 1 mL of triamcinolone 40 mg/mL mixed with 3 to 5 mL of lidocaine 1%.
Lateral Epicondyle (Tennis Elbow)
The point of maximal tenderness over the lateral epicondyle is identified, and a 25-gauge needle is inserted perpendicular to the skin, peppering the peritendinous tissue. A typical dose is 0.5 mL of betamethasone mixed with 1 to 2 mL of lidocaine 1%. Direct tendon injection must be avoided.
Trigger Finger (Flexor Tendon Sheath)
The A1 pulley is palpated at the metacarpophalangeal joint crease. A 25-gauge needle is inserted at a 45-degree angle into the tendon sheath; if the needle moves with finger flexion, it should be repositioned slightly. A typical dose is 0.25 to 0.5 mL of betamethasone or dexamethasone mixed with 0.5 mL of lidocaine 1%.
Greater Trochanteric Bursa
The patient is positioned in the lateral decubitus position, and the point of maximal tenderness over the greater trochanter is identified. A 22-gauge, 1.5- to 3.5-inch needle (depending on body habitus) is inserted perpendicular to the skin. A typical dose is 1 mL of triamcinolone 40 mg/mL mixed with 3 to 5 mL of lidocaine 1% or bupivacaine 0.25%.
Ultrasound-Guided Injections
Ultrasound guidance improves accuracy for deep structures, obese patients, and cases where landmark-guided attempts have failed. It is particularly useful for the glenohumeral joint, hip joint, and small joints of the hand and foot. Real-time visualization allows confirmation of needle placement and observation of fluid distension, while reducing the risk of inadvertent tendon injection.
Synovial Fluid Analysis
When aspiration yields fluid, it should be sent for cell count with differential, crystal analysis, and Gram stain with culture. A white blood cell count less than 200 is normal, 200 to 2,000 is non-inflammatory, 2,000 to 50,000 is inflammatory, and greater than 50,000 should be considered septic until proven otherwise. Crystal analysis identifies monosodium urate crystals in gout and calcium pyrophosphate crystals in pseudogout. Glucose and protein levels are optional adjuncts.
Key Clinical Pearls
Never inject through infected skin; even minor cellulitis overlying a joint is an absolute contraindication. Immediate pain relief after injection of local anesthetic confirms accurate needle placement and supports the diagnosis. Corticosteroid injections should be limited to three to four per joint per year to minimize cartilage damage and soft tissue atrophy. Septic arthritis should always be considered before injecting an acutely swollen, warm, erythematous joint, and fluid should be aspirated and analyzed first. Ultrasound guidance increases accuracy from approximately 70% to over 95% for many injection sites and should be used when available.
References
- Cardone DA, Tallia AF. Joint and soft tissue injection. Am Fam Physician. 2002;66(2):283-289.
- Daniels EW, Cole LJ, Garlick KR. Joint and soft tissue injections. FP Essentials. 2019;486:11-17.
- Kompel AJ, Roemer FW, Murakami AM, et al. Intra-articular corticosteroid injections in the hip and knee: perhaps not as safe as we thought? Radiology. 2019;293(3):656-663.
- Berkoff DJ, Miller LE, Block JE. Clinical utility of ultrasound guidance for intra-articular knee injections: a review. Clin Interv Aging. 2012;7:89-95.