Indications for Aspiration and Injection of Joints and Periarticular Lesions
Aspiration and injection of joints and periarticular synovium-lined cavities (bursae and tendon sheaths) and injection of soft-tissue lesions (entheses, tendinitis, compression neuropathies, epidural sac) are indicated in the diagnosis and treatment of various musculoskeletal disorders. These are summarized in Table 10-1 .
|Diagnostic synovial fluid analysisSeptic arthritis, hemarthrosis, crystal arthritis, differentiation of inflammatory from noninflammatory arthritis|
|Repeated needle (closed) drainage of septic arthritis|
|Drainage of large hemorrhagic or tense effusions|
|Injection of therapeutic agents|
|Local control of inflammatory synovitis; periarticular lesions; efficacy in OA is less clear|
|IA Hyaluronate Preparations|
|Relief of pain in joints affected by OA|
|Control of chronic synovitis in inflammatory arthritis (radioactive synovectomy) using colloidal 198 gold (large joints), 90 yttrium (large joints), 186 rhenium (medium-sized joints), 169 erbium (small joints), and 32P chromic phosphate|
Contraindications for Aspiration and Injection of Joints and Periarticular Lesions
The relative contraindications to intraarticular (IA) and periarticular injections of corticosteroids are summarized in Table 10–2 . If infection is suspected in the joint, bursa, or tenosynovium, it should be aspirated and the synovial fluid examined for cell count, differential, and culture. In the setting of an inflamed joint, if the clinical diagnosis is unclear, or the aspirated fluid suggests possible infection, the aspirated fluid should be sent for cell count, differential, culture, and polarizing microscopy for crystals ( Table 10-3 ). Intrasynovial corticosteroid injections may exacerbate an infection and are not recommended if there is suspicion of infection. Joint injection is also best avoided if there is bacteremia or infection of the overlying skin or subcutaneous tissue or in the presence of overlying skin lesions, such as extensive psoriatic plaques.
|Suspected joint infection|
|Overlying cellulitis or other skin infection|
|Thrombocytopenia, bleeding disorders|
|Osteonecrosis, IA fracture or severely destroyed or unstable joint|
|Tendon tears and steroid injections near the Achilles tendon|
|Multiple or high-dose IA steroid injections in patients with uncontrolled diabetes mellitus, hypertension, congestive heart failure, or psychosis|
|Skin surface area covered by psoriatic plaques|
|Hypersensitivity to local anesthetic (steroid alone may be used)|
|Normal||Osteoarthritis||Inflammatory Arthritis||Septic Arthritis|
|Gross appearance||Clear||Clear||Cloudy or opaque||Opaque|
|Total synovial fluid WBC/mm 3||< 200||200–1000||1,000–75,000||> 50,000|
|% Polymorphonuclear cells||< 25||< 50||> 50||> 90|
|Polarizing microscopy||Negative||Negative||Positive for crystals in gout or pseudogout||Negative|
Bleeding disorders and severe thrombocytopenia are relative contraindications to joint aspiration. However, if diagnostic aspiration is deemed necessary, needle aspiration may be carried out after an appropriate cover for the bleeding disorder, such as factor VIII administration in a patient with hemophilia. Anticoagulant therapy with warfarin in the therapeutic range is not considered a contraindication to joint aspiration or injection.
Aspiration is recommended if prosthetic joint infection is suspected. However, a steroid injection into a prosthetic joint carries a particularly high risk of infection and is best avoided. Another risk is systemic absorption of a proportion of injected corticosteroid, which can result in worsening of uncontrolled diabetes mellitus, hypertension, congestive heart failure, or psychosis; such injections should be used cautiously in these patients.