INTRODUCTION — A needle is inserted into a joint for two main indications: aspiration of fluid (arthrocentesis) for diagnosis or for injection of medications. In practical terms, most injections into joints consist of a glucocorticoid, a local anesthetic, or combinations of the two. Soft tissue and intraarticular glucocorticoid injections are generally safe, but they can result in systemic and local adverse effects.
The complications of joint aspiration or glucocorticoid injection in adults are discussed here. The technique and indications for joint aspiration and intraarticular and periarticular injections of glucocorticoids and intraarticular hyaluronate derivatives, as well as the choice and frequency of agents for injection, are discussed separately. (See "Joint aspiration or injection in adults: Technique and indications" and "Intraarticular and soft tissue injections: What agent(s) to inject and how frequently?".)
INFECTIOUS COMPLICATIONS
Septic arthritis — The development of a septic joint is the most feared complication of any joint aspiration or injection. The frequency of this complication is estimated to lie between 1 in 1000 to 3000 [1,2]. Estimates using imputed, rather than measured, denominators place the rate as much as five times less [3]. Although this range of estimated frequency of iatrogenic septic arthritis is broad, we suspect that this complication rate lies closer to the higher 1 infection per 1000 to 3000 procedures. This latter estimate is supported by a comprehensive nationwide study in which data from all arthrocentesis procedures performed over a 13-year period were reviewed, resulting in a reported frequency of septic arthritis of 1 in 2600 procedures [1], as well as data from another registry study of 22,370 procedures [2].
The rates of iatrogenic infections can be reduced by using appropriate measures when performing joint aspirations or injections [4]. These measures include using triple concentric iodine preparation of the skin or chlorhexidine preparation, rather than just alcohol alone; "no touch" technique if using nonsterile universal precaution gloves; single-dose vials when these are available from the institutional supplies (multidose vials are most common in outpatient and office practices); changing to a new needle after drawing up the medication and before injecting it; cleaning the tops of the vials with an alcohol swipe prior to drawing up the injection; and avoiding preparing the syringe many hours, or days, ahead of when it is to be used. (See "Joint aspiration or injection in adults: Technique and indications", section on 'Sterile preparation'.)
Although all needle sizes can theoretically inoculate a joint by depositing a core of tissue within the joint [5], there is some evidence from animal models suggesting that translocation of bacteria is correlated both with needle size and with overlying infected tissue (aspirating through cellulitis) [6]. However, there are no human data to support using a preferred needle size to reduce the risk of translocation of bacteria during joint aspiration. Presumably, aspirating through cellulitis would be less of a concern if the patient has already been established on an antibiotic regimen. In addition, ultrasound guidance may be used to assist with aspiration via a less familiar route chosen to avoid cellulitis.
A septic joint must be distinguished from postinjection flare (see 'Postinjection flare' below). Infection should be suspected if the flare lasts longer or begins later than 48 hours after injection. The usual postinjection flare lasts hours rather than days. Other findings suggestive of an iatrogenic septic joint include a crescendo pattern of pain, redness or drainage around the injection site, and fever or malaise. (See "Septic arthritis in adults".)
There is inconclusive evidence that intraarticular glucocorticoid injection preceding total joint arthroplasty of a large joint will increase the probability of septic joint as a complication of the surgery. This is discussed in detail separately. (See "Intraarticular and soft tissue injections: What agent(s) to inject and how frequently?", section on 'Contraindications'.)
A detailed discussion on the diagnosis and management of septic arthritis can be found elsewhere. (See "Septic arthritis in adults".)
Septic bursitis — The superficial or subcutaneous bursae are predisposed to infection as a result of skin trauma. Septic bursitis can result from direct inoculation due to puncture of the overlying skin during an injection. (See "Septic bursitis".)
Although fluid aspiration is necessary for suspected septic bursitis, aspiration of the olecranon and other superficial bursae can also be complicated by persistent leaking from the needle track, which can further increase the risk of iatrogenic infection.
NONINFECTIOUS COMPLICATIONS
Technique-related
Tendon rupture — Tendon rupture appears to be associated with injections placed directly within tendons and may be accelerated by underlying tendon pathology. Tendon rupture is most commonly encountered when undiluted glucocorticoid is injected near the rotator cuff or near the insertion of the long head of the biceps tendon. This complication may be more common with the posterior approach, which can be directed upward in the direction of the subdeltoid bursae and rotator cuff, than with the anterior approach, which is only intraarticular.
Neurovascular damage — Nerve atrophy or necrosis occurs when glucocorticoids enter the nerve sheath directly, an event that usually occurs only with carpal tunnel injections that come quite close to the median nerve. This complication can generally be avoided when performed by a subspecialist with specific training (eg, a hand surgeon or a rheumatologist), knowledge of the regional anatomy, and especially if ultrasound guidance is available.
Glucocorticoid-associated toxicity
Postinjection flare — Postinjection flare is one of the more common acute side effects of an intraarticular glucocorticoid injection, occurring after approximately 5 percent of injections [3]. It is characterized by a localized inflammatory response that typically occurs and resolves within 48 hours after injection. Postinjection flares are thought to result from a chemical synovitis in response to the crystals in the glucocorticoid solution. Triamcinolone, which is less soluble than the other more commonly used preparations, is associated with more postinjection flares [7,8].
In some cases, the flare can be difficult to distinguish from iatrogenic septic arthritis. One helpful clue is that most iatrogenic joint infections seem to develop clinical signs a bit more slowly than a crystal-induced flare. In addition, postinjection flares primarily occur with soft tissue, tendon, or trigger point injections, while infections are rare and occur primarily with intraarticular injections.
Facial flushing — Facial flushing after glucocorticoid injection has been reported in as many as 10 percent of patients and is more common in women [3]. The onset of flushing is usually within a few hours after injection and may persist for a few days [9]. Facial flushing may often be described as an "allergic reaction" by some patients but is probably not a true allergy in most patients.
Local skin or fat changes — Skin or fat atrophy and skin hypopigmentation are more commonly observed with injections of superficial structures (eg, ganglia, tendon sheath) but can also occur with deeper injections. Skin or fat atrophy are observed clinically as a depressed area of skin, which may develop weeks or months after the injection. Darkly pigmented skin is more susceptible to hypopigmentation and depigmentation, and patients should be informed of such a potential complication (picture 1).
Osteonecrosis — An uncommon complication of intraarticular glucocorticoids is osteonecrosis (ischemic or avascular necrosis of bone) [10-12]. The risk of this complication is reported to range from less than 0.1 to 3 percent of injected joints [13,14]. However, the former figure seems more consistent with clinical practice. It has been hypothesized that the severity of the underlying joint disease may contribute more to this risk than the injection itself.
Cartilage damage — There is limited evidence suggesting that repeated intraarticular glucocorticoid injections can result in cartilage loss [8]. In a randomized trial with 140 patients with symptomatic knee osteoarthritis, those who received intraarticular triamcinolone every three months for two years demonstrated greater cartilage volume loss on magnetic resonance imaging (MRI) compared with those who received placebo injections [15]. A previous randomized trial with two-year follow-up found no difference in adverse effects when comparing intraarticular glucocorticoids with placebo injections; however, radiography was used to assess progression of osteoarthritis, which is a less sensitive measure of cartilage damage compared with MRI [16]. It is possible that the effect of glucocorticoid injection on joint cartilage in inflammatory arthritides such as rheumatoid arthritis may not be as deleterious when considering the negative effects on cartilage associated with the underlying disease process. In one study, glucocorticoid injection into large joints affected by rheumatoid arthritis did not result in an increased rate of total joint arthroplasty in those joints during long-term follow-up [17].
The role of glucocorticoid injections in the management of osteoarthritis and rheumatoid arthritis are discussed in detail separately. (See "Management of moderate to severe knee osteoarthritis", section on 'Limited role of intraarticular glucocorticoid injections' and "Initial treatment of rheumatoid arthritis in adults", section on 'Intraarticular glucocorticoids'.)
Systemic effects — Glucocorticoid injections can cause transient hyperglycemia, which may pose a risk to patients with diabetes mellitus (DM) by raising the blood glucose to hyperglycemic levels. However, patients generally experience an isolated increase in blood glucose for one to two days, which rarely poses a significant clinical risk when the DM is well controlled. (See "Comorbidities that impact management of osteoarthritis", section on 'Diabetes mellitus'.)
A rare side effect related to systemic absorption of intraarticular glucocorticoids is suppression of the hypothalamic-pituitary axis [18]. Other rare systemic complications that can be seen are ecchymoses, menstrual irregularity, accelerated cataract formation, and osteoporosis. Bone metabolism markers suggest that bone metabolism recovers completely in one to two weeks after the injection [16,19]. Glucocorticoid-induced osteoporosis is probably not a major concern for the majority of patients who have reasonably long intervals between their injections. (See "Clinical features and evaluation of glucocorticoid-induced osteoporosis" and "Major side effects of systemic glucocorticoids".)
Bleeding — Local bleeding is uncommon in patients without a bleeding diathesis or who are not on anticoagulation. Holding pressure over the puncture site with sterile gauze is typically sufficient to stop local venous bleeding. A rare complication of hemarthrosis due to an arterioarticular fistula after arthrocentesis has been described [20]. The risk of bleeding complications in patients receiving therapeutic anticoagulation is low and is discussed in detail separately. (See "Joint aspiration or injection in adults: Technique and indications", section on 'Approach to the patient on anticoagulants'.)
Allergic reaction — The incidence of allergic reactions is unknown. Facial flushing may often be misinterpreted as an allergic reaction by some patients.
Other — Other rare complications that have been described include dystrophic calcification, Charcot-like arthropathy, or embolia cutis medicamentosa (also known as livedoid dermatitis and Nicolau syndrome). In addition, rare cases of rapidly destructive hip disease have been described in association with intraarticular glucocorticoid injections in the hip and are discussed in more detail separately. (See "Management of hip osteoarthritis", section on 'Limited role of intraarticular glucocorticoids'.)
SUMMARY AND RECOMMENDATIONS
●The development of a septic joint is the most feared complication of any joint aspiration or injection. The frequency of iatrogenic septic arthritis following joint aspiration or injection is estimated to be approximately 1 in 3000 procedures. Infection, rather than the more common postinjection flare, should be suspected if the flare lasts longer than or begins later than 48 hours after injection. The usual postinjection flare lasts hours rather than days. (See 'Septic arthritis' above and "Septic arthritis in adults".)
●The superficial or subcutaneous bursae are predisposed to infection as a result of skin trauma. Septic bursitis can result from direct inoculation due to puncture of the overlying skin during an injection. (See 'Septic bursitis' above and "Septic bursitis".)
●Noninfectious complications that are directly related to technique include tendon rupture and neurovascular damage. Tendon rupture appears to be associated with injections placed directly within tendons and may be accelerated by underlying tendon pathology. Nerve atrophy or necrosis occurs when glucocorticoids enter the nerve sheath directly. (See 'Tendon rupture' above and 'Neurovascular damage' above.)
●Other complications of intraarticular injections related to the glucocorticoid component include postinjection flare, facial flushing, local skin or fat changes, osteonecrosis, cartilage damage, systemic effects (eg, hyperglycemia), bleeding, allergic reactions and other rare complications (eg dystrophic calcification, Charcot-like arthropathy, or embolia cutis medicamentosa [also known as livedoid dermatitis and Nicolau syndrome]). (See 'Glucocorticoid-associated toxicity' above.)