Intraarticular injections with corticosteroids and anesthetic can be a useful treatment option for patients with disabling peripheral joint pain. The anesthetic injected can provide useful diagnostic information and help determine a patient’s pain generator. These forms of injections are performed in conjunction with a comprehensive treatment program. This chapter will review common indications for intraarticular corticosteroid injections, dosing of medications injected, and discuss the technique for upper extremity intraarticular joint injections.
Indications for Intraarticular Steroids
The most common use of corticosteroids in the peripheral joints is in patients with rheumatoid arthritis. These drugs are used specifically to reduce inflammation and provide relief from pain attributable to synovitis and conditions associated with rheumatoid arthritis. Other indications for the use of corticosteroids into joints include painful osteoarthritis and adhesive capsulitis. Aspiration of synovial fluid for pain relief and laboratory evaluation of the synovial fluid and arthrography for the evaluation of joints are common diagnostic tools that facilitate the rehabilitation of painful joints.
Drugs: Action, Selection, Dosage
Corticosteroids produce significant antiinflammatory effects. Numerous long-acting corticosteroid ester preparations are available. The most widely used corticosteroids include triamcinolone acetonide (Kenalog), triamcinolone hexacetonide (Aristospan), betamethasone sodium phosphate (Celestone) and betamethasone acetate (Soluspan), and methylprednisolone acetate (Depo-Medrol). These compounds were developed to reduce undesirable hormonal side effects with less rapid dissipation from the joint. None of these corticosteroid derivatives appears to have any superiority over another; however, triamcinolone hexacetonide is the least water-soluble preparation and thus provides the longest duration of effectiveness within the peripheral joint space. Systemic absorption after peripheral joint injection occurs within 2 to 3 weeks. Improvement of inflammatory processes remote from the injection site demonstrates that intraarticular corticosteroids exert a systemic effect. The pharmacology of corticosteroids and anesthetics is discussed in Chapter 2 .
Estimated dosages for the peripheral joints vary widely and usually depend on the size of the joint. The larger joints, such as the knee and shoulder, respond well to a 40-mg dose of methylprednisolone acetate or the equivalent of another agent. The smaller joints, such as the elbow and ankle, respond to a 20- to 30-mg dose of methylprednisolone acetate or the equivalent. Even smaller joints, such as the acromioclavicular and sternoclavicular joints, respond to a 10- to 20-mg dose of methylprednisolone acetate or the equivalent.
The number of injections per joint is also widely variable. Commonly, joints that are injected for the purpose of reducing inflammation in rheumatoid arthritis will be injected many times over the course of the disease process. These multiple injections have been shown to cause interference with normal cartilage protein synthesis. However, it has also been demonstrated that patients with long-standing rheumatoid arthritis who do not receive intraarticular corticosteroid injections have joint disuse and decreased function much sooner than those who receive the injections. For the purposes of pain reduction in osteoarthritis as well as an adjunct in the mobilization of the treatment of adhesive capsulitis, injections at the rate of one per 4 to 6 weeks for a maximum of three injections is the most commonly accepted regimen. This regimen, of course, is subject to the patient’s response to his or her overall treatment plan, of which the intraarticular corticosteroid injection is but one part.
It is usual practice to combine the corticosteroid medications with an anesthetic substance, such as procaine (Novocain) or lidocaine (Xylocaine) or the equivalent. The combined use of corticosteroids and anesthetic agents provides a larger volume of injectable material with which to bathe the joint more adequately. The added effect of analgesia is also desirable for patient comfort and for a more immediate response to treatment. Thus, the patient may obtain immediate pain relief and provide valuable feedback with which to help determine the overall rehabilitation plan. The usual anesthetic injected is lidocaine, 1% without epinephrine, with which the practitioner can provide a preliminary skin wheal and a control test before proceeding with the deeper injection. Bupivacaine (Marcaine, Sensorcaine), 0.25% or 0.5%, is also useful in providing a longer-acting analgesic effect for the patient. The dosages of lidocaine and bupivacaine also vary widely with the size of the joint. Usually, the smaller joints such as the acromioclavicular, sternoclavicular, and elbow joints would take 1 to 2 mL of 1% lidocaine combined with the corticosteroid. The glenohumeral, knee, and hip joints would take 2-4 mL of anesthetic agent. Bupivacaine is often preferable for non–weight-bearing joints such as the shoulder, elbow, acromioclavicular, and sternoclavicular joints, so long as these joints can be somewhat immobilized for several hours. Likewise, lidocaine is the drug of choice for injections in the weight-bearing joints, such as the knee, because its duration is much shorter and, thus, the joint is subject to less postinjection trauma by the seemingly compliant patient.
Contraindications and Complications
The clinician must be acutely sensitive to contraindications and complications of intraarticular corticosteroid therapy. Some of the most obvious contraindications include infection of the joint or of the skin overlying the joint. A patient with generalized infection also should be considered an unsuitable candidate for corticosteroid injection. Injection of corticosteroids may render a joint susceptible to hematogenous seeding from more distant skin lesions. Thus, the overall health of the patient must be assessed before considering the use of intraarticular corticosteroids. Other obvious contraindications include hypersensitivity to any of the anesthetic preparations or the corticosteroids themselves. Patients receiving intraarticular injections in the presence of anticoagulants would be susceptible to bleeding. Determination of prothrombin time is suggested before injection therapy in these patients.
Patients with a recent injury to the joint such as a ligamentous destruction or bony destruction of the underlying joint should not be subjected to corticosteroid therapy. Instead, aspiration of the joint may be indicated if there is a relatively large inflammatory effusion. Soft tissue or bony tumors at or near the underlying joint would also be a major contraindication to corticosteroid injections.
Even small doses of corticosteroids with intraarticular injections may trigger episodes of hyperglycemia, glycosuria, and even electrolyte imbalance in patients with diabetes; caution must be exercised in such situations.
Although rare, infections can be a serious complication. Usually, infections can be avoided by using an aseptic technique. Infections may be quite subtle in patients with long-standing rheumatoid arthritis and in those receiving immunosuppressive agents. The most common organism is Staphylococcus aureus . One must also use caution in geriatric patients and in those with debilitating diseases.
Hypercorticism from systemic corticosteroid therapy may be a complication if the patient receives multiple intraarticular injections in succession or if the patient is receiving concomitant oral cortisone therapy. Corticosteroid arthropathy with avascular necrosis also has been reported but is rare and has not been noted to occur after single corticosteroid injections. Joint capsule calcification is also a potential complication of multiple intraarticular corticosteroid injections.
Depigmentation and subcutaneous fat necrosis occasionally occur. The depigmentation is cosmetically unacceptable, especially in individuals with darker skin in whom it can be quite noticeable. Fat necrosis usually is not a complication in superficial joints that have minimal amounts of overlying fat tissue. Using a small amount of lidocaine to flush the needle to avoid leaving a needle track of corticosteroid suspension will help to minimize this complication.
A common complication in patients with rheumatoid arthritis who are receiving corticosteroid injections in the joints is “postinjection flare” (the joint appears inflamed or even infected), which tends to subside spontaneously in 24 to 72 hours. Other less common complications include Tachon syndrome (intense dorsal spine pain immediately following an injection that quickly subsides) and chorioretinopathy.
Alternatives to Corticosteroids
Alternatives to intraarticular corticosteroids include viscosupplementation and plasma-rich platelet (PRP) injections. Viscosupplementation injections use gel-like substances such as hyaluronates to supplement the viscous properties of synovial fluid and have been approved for use in the knee joint. Other joints including the shoulder have been treated with this form of injections with good results.
Plasma rich platelet injections use concentrated platelets from autologous blood to stimulate a healing response in damaged tissue. Blood is drawn from the patient and placed in a centrifuge. The concentrated platelets are removed and reinjected directly into the patient’s abnormal joint, usually under ultrasound guidance. These concentrated platelets produce growth factors that include platelet derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and transforming growth factor-beta (TGF-β). These compounds are instrumental in attracting cells that promote healing by stimulating neovascularization and cellular reproduction. The efficacy of PRP injections and appropriate clinical indications (when and where it should be used) are currently being researched and yet to be definitively determined. Initial results of clinical studies appear promising.
Techniques for Intraarticular Injections
When the clinician has established that a peripheral joint needs to be injected or aspirated, the specific preparation for the injection is essentially the same for all joints. Thorough understanding of the underlying anatomy is important to accomplish a painless injection. The optimal site for injection of the joint usually is the extensor surface at a point where the synovium is closest to the skin. Approaching the joint from the extensor surfaces allows the injection to be as remote as possible from any major arteries, veins, and nerves. When the site of injection has been determined, it can be marked with the needle hub or a retracted ballpoint pen by pressing the skin to produce a temporary indentation to mark the point of entry. The skin is then prepared by cleansing a generous area with a detergent or cleaner such as an iodine-based surgical scrub. This area is then painted with an antiseptic solution and allowed to dry. Aseptic technique is always advised, including the wearing of sterile gloves so that the area to be injected may be continually palpated and the anatomy appreciated throughout the procedure. A small skin wheal may then be raised using 1% lidocaine with no epinephrine (or an equivalent anesthetic agent). A 27-gauge skin needle approximately 0.75 to 1.0 inch long is used with approximately 1 mL of anesthetic agent. For joints distended with fluid or those that are particularly close to the surface of the skin, such as the acromioclavicular and sternoclavicular joints, the raising of a skin wheal or preanesthesia is usually not necessary. If a patient is particularly apprehensive about the injection procedure, one of the vapo-coolant sprays such as dichlorotetrafluoroethane or ethyl chloride may provide adequate anesthesia.
After the skin wheal is raised, a 25- or 22-gauge needle approximately 1.5 inches long may be used to introduce the injectant. The needle is then slid gently into the joint, with the clinician avoiding a strong thrusting motion. Just before beginning the actual injection, the practitioner should aspirate to ensure there is no return of blood. After ascertaining the needle’s positioned in the joint space, the injectable material should be introduced using slow, steady pressure on the plunger.
If the joint is to be aspirated before introduction of a corticosteroid, the same technique is used in preparation; however, a larger needle may be introduced, such as a 20- or even an 18-gauge needle. Again, slow, steady pressure is used when the needle is introduced into the joint. The aspirate is then withdrawn with the practitioner gently pulling the plunger on the syringe with the dominant hand, holding the syringe barrel steady with the nondominant hand. If it is suspected that not all of the aspirate has been obtained from the joint, the needle tip may be moved around within the joint, and the joint itself may be “milked,” using steady pressure with the opposite hand on the joint itself by kneading the skin toward the site of aspiration. After all of the available fluid is aspirated, the needle may be left in place with the syringe removed. A separate syringe may then be attached to the aspirating needle, and the injectant may then be introduced into the joint itself. Again, a slow, gentle introduction of the injectable material is desired.
If resistance is met during the time of the injection, the needle should be readjusted so that there is no resistance. Any time the needle is readjusted, the plunger on the syringe should be withdrawn to ensure that the needle tip does not pierce a blood vessel.
After the drug or drugs have been injected, the needle is withdrawn and mild pressure is applied with a sterile gauze pad to prevent bleeding. Whenever the injected material includes corticosteroids, a slight amount of lidocaine may be used to clear the needle before withdrawal. As mentioned earlier, this technique prevents leaving a steroid track through the adipose tissue and skin, which may cause depigmentation or subcutaneous necrosis.
Psychological care of the patient is important to the success of these injections. Throughout the procedure, the patient must be coaxed to achieve muscle relaxation and reassured of the importance of the procedure. It is likewise important that the patient be reminded of the practitioner’s skill with and knowledge of the procedure. After the procedure, the patient should be assessed carefully to be sure that he or she is not exhibiting a vasovagal response and that appropriate measures are taken to prevent any secondary harm, such as falling as a result of transient hypotension.
Upper Extremity Joints
The glenohumeral joint is subject to multiple traumatic and pathologic problems more frequently than any other joint except the knee. The anatomy of the shoulder must be well understood for a relatively painless injection to be achieved. In entering the subacromial space in the shoulder, there is little anterior space for placement of the needle. A lateral or posterior approach may be more desirable.
When injecting the shoulder for problems such as bicipital tendinitis, the anterior approach is necessary ( Fig. 9-1 ). The patient is placed in a sitting position, the anterior portion of the shoulder is prepared aseptically, and, if desired, a cutaneous wheal is raised medial to the head of the humerus and just inferior to the tip of the coracoid process. It is useful to have obese patients lie supine with the forearm across the abdomen. In this position, the shoulder may be passively rotated internally and externally to identify the head of the humerus. The coracoid process is then easily palpated. The needle is directed in the anteroposterior plane just lateral to the coracoid process. The needle is advanced into the groove between the medial aspect of the humeral head and the glenoid. No resistance should be felt as the needle is advanced.