CHAPTER 192 Joint and Soft Tissue Aspiration and Injection (Arthrocentesis)
Joint and soft tissue aspiration and injection are both clinically rewarding and relatively simple office procedures. Steroid injection into joints fell into disfavor for many years because the procedure was overused and abused. When appropriate guidelines are followed, however, complications are extremely rare, and the injections can be very beneficial to the patient by reducing symptoms. The alternative to focal treatment with injection is usually systemic nonsteroidal anti-inflammatory drugs (NSAIDs), which have significant toxicity with prolonged use.
Primary care physicians should master the technique of aspiration and injection for many reasons. If the physician aspirates an inflamed joint, a diagnosis can be made immediately. If a joint is distended, pain can be relieved rapidly by aspirating the fluid. Injecting an anesthetic or steroid solution can give focal pain relief without the toxicity of the systemic medications and provide valuable information regarding diagnosis.
The clinician should not withhold the benefits of injection therapy because of incomplete familiarity with the precise anatomy involved. Knowledge of soft tissue and bony landmarks provides a reliable method for identification of needle insertion sites. The emerging role of musculoskeletal ultrasound in office-based practice additionally offers new opportunities to improve diagnostic and therapeutic techniques. The reader may want to refer to Chapter 191, Ganglion Treatment, for related information.
Corticosteroids have a marked effect on inflammation. There are no good data to indicate that steroid injections decrease the long-term adverse effects of chronic degenerative osteoarthritis, but there is no doubt that they result in acute symptomatic improvement, especially over the first 1 to 4 weeks. The Cochrane Collaboration report on osteoarthritis supports the use of the intra-articular corticosteroids in the treatment of osteoarthritis (OA) of the knee.
Box 192-1 lists the conditions that are improved with local corticosteroid therapy. Localized pain that persists more than a few weeks after a trial of NSAIDs warrants an injection with steroids. Injections should be considered primarily when the potential toxicity or intolerance to NSAIDs outweighs the risk of local corticosteroids. Tramèr and colleagues noted in their meta-analysis that individuals chronically (≥2 months) using NSAIDs had a 1 : 1220 chance of dying from a gastrointestinal complication. In contrast, death occurring after intra-articular injections comes predominantly from septic arthritis, which occurs in anywhere from 1 : 3000 to 1 : 50,000 cases—with a mortality rate of about 15%. Morbidity risks associated with prolonged NSAID use are even greater.
Box 192-1 Conditions Improved with Local Corticosteroid Injection
Adapted from Pfenninger JL: Injections of joints and soft tissue. Part I. General guidelines. Am Fam Physician 44:1196, 1991.
Synovial fluid functions as a lubricant and a shock absorber in the joint. In OA, it retains very little of these intrinsic physical properties. At a critical load, normal synovial fluid changes its mechanical properties from viscous lubricant to elastic shock absorber. This change occurs between walking and running and is determined by the dynamic stress of both the frequency and the force of the load—a property which is diminished in OA. In addition, the concentration of hyaluronan in the synovial fluid in patients with OA is less than normal. Injected hylans and hyaluronans have properties similar to normal synovial fluid, and although they may only remain in the knee less than 2 weeks, the beneficial effects can persist up to a year (mean duration of 8.2 months). There is some evidence that they stimulate endogenous production of the synovial fluid. There is no evidence that viscosupplementation retards the progression of joint deterioration, but a recent Cochrane Review concluded that viscosupplementation showed beneficial effects on pain and patient function; this modality shows promise of postponing for years the need for total knee replacement. Studies are ongoing to assess its efficacy in other joints, because it is currently only Food and Drug Administration (FDA)–approved for use in the knee. The materials injected (hylans and hyaluronans) are pharmacologically inert so the FDA classifies them as “devices,” not “drugs.”
Prolotherapy is an alternative form of injection therapy, utilized by some clinicians to treat chronic musculoskeletal pain syndromes. Prolo is derived from proliferation, because the treatment causes the proliferation (growth and formation) of new connective tissue in areas that have become weak. The concept behind this technique is to stimulate the body’s own inflammatory cascade in order to promote reabsorption of unhealthy tissue, such as degenerative fibroblasts in injured tendons, and the creation of new, healthy tissue. Inflammation-promoting agents (>10% dextrose solutions, phenol- or sodium-morrhuate–containing solutions, autologous blood, platelet rich plasma [PRP]) are injected into the area of injury, often with the aid of ultrasound to best localize the target.
Prolotherapy is most often described in use with tendinopathy, and there is some evidence to suggest that it is an effective therapy in treating the degenerative tissues identified. The treatment most likely achieves its maximal benefit when coupled with physical therapy focused on further stimulating growth of new tendinous tissue. As prolotherapy is an emerging technique that can be highly operator dependent, those interested in providing this service are encouraged to consult with a prolotherapist or complete a course of instruction prior to beginning prolotherapy injections in an office practice.
In the past, joint injections were frequently performed without gloves with only an alcohol wipe. In contrast, some physicians still use an extensive sterile draping procedure. Although the former is most likely inadequate, the latter is probably unnecessary unless the patient is immunosuppressed, diabetic, or at high risk of infection. Most injections are administered after an alcohol or povidone–iodine wipe. Gloves (sterile or nonsterile) should be used. When a culture is anticipated, sterile gloves are more customary. Masks are unnecessary.
NOTE: There are two reasons to use single-dose vials. First, no allergic reaction to lidocaine (an amide) has ever been reported. Although rare, reactions do occur to the preservative (parabens) that is used in multidose vials. Local anesthetics with an ester base (e.g., procaine [Novocain]) can cause allergic reactions. So, using a single-dose vial of lidocaine makes it highly unlikely that there will be a reaction. Second, many steroids will precipitate when mixed with the parabens preservatives. This leads to uneven distribution in the syringe as well as the injection of small crystals into the site, and these crystals themselves could cause an inflammatory process (Fig. 192-1). Theoretically, a homogeneous solution would be more efficacious, although no studies have looked at the issue and many feel it is a moot point and of little concern. Certain manufacturers, however, do not recommend injecting precipitated steroids.
Figure 192-1 A, Example of precipitation of steroid (Celestone Soluspan) when mixed with lidocaine solution from a multidose vial. B, Steroid in solution (Celestone Soluspan) when mixed with lidocaine from a single-dose vial. It is preferable to have the steroid in solution rather than in precipitated form.
(Courtesy of The Medical Procedures Center, PC, John L. Pfenninger, MD.)
Many practitioners will use a longer-acting local anesthetic such as bupivacaine (Marcaine). Although this addition in most cases will not have any untoward effects, it should be noted that there have been instances of myotoxicity associated with bupivicaine, and given that it is only intended to provide short- to medium-term relief of symptoms, one might question its regular use.
|Relative Anti-inflammatory Potency
|Approximate Equivalent Dose (mg)
|Prednisolone tebutate (Hydeltra-TBA)
|Triamcinolone (Aristocort, Aristospan, Kenalog)
|Methylprednisolone acetate (Depo-Medrol)
|Betamethasone (Celestone Soluspan)
Adapted from Leversee JH: Aspiration of joints and soft tissue injections. Prim Care 13:572, 1986.
A reasonable rule of thumb is that the greater the water solubility of the corticosteroid, the more rapid the onset of action, and the shorter the duration of effect. Thus, steroids with a lower degree of water solubility would in general be more effective in a chronic disease process, such as OA, whereas an acute inflammatory process might be more responsive to a shorter-acting preparation (Table 192-3).
|Solubility (% wt/vol)
NOTE: It is best to pick out one or two preparations and learn them well. It is not necessary to be familiar with all the drugs listed. There is no consensus in the literature as to the “best” drug or the optimal dosages. Table 192-2 offers our recommendations for appropriate dosing.
Inform the patient of the risks, benefits, and possible complications of injection therapy. This information is especially important if steroids are used. Rarely is there ever a complication from the use of lidocaine alone. However, with steroids, and especially with repeated injections, there are some adverse consequences (see the “Complications” section and) Table 192-4. Inform the patient that there is always a possibility for infection with the injection, although this is extremely rare. Bleeding into a joint can occur, but this generally does not happen unless the patient has a coagulopathy. The injection may actually cause more pain during the first 24 to 36 hours. This reaction is called steroid flare. If the pain lasts for more than 72 hours, evaluate the patient for the possibility of a septic joint. Warn the patient of a possible failure to obtain relief, and that a second or even a third injection may be needed. Whether or not steroids have significant adverse effects on the cartilage and bone itself when steroids are injected into the joint space, and the degree of this reaction, is controversial. However, the effects would appear to be minimal, especially when used appropriately. Allergic reactions are very rare. Tendon ruptures should be avoidable if the injection is placed peritendinously instead of within the tendon itself. However, rupture is always a possibility. As a final precaution, warn the patient that a steroid placed too close to the surface of the skin occasionally causes atrophy (Fig. 192-2). This reaction may leave the patient with depigmentation and a slight indentation in the skin.
|Skin atrophy, depigmentation
|Iatrogenic infectious arthritis
|Transient paresis of injected extremity
|Asymptomatic pericapsular calcification
|Acceleration of cartilage attrition
From Gray RG, Gottlieb NL: Intra-articular corticosteroids: An updated assessment. Clin Orthop Relat Res 177:253, 1983.
Figure 192-2 Fatty atrophy. This patient received a steroid injection for lateral epicondylosis approximately 11 months before this photo was taken, showing an example of steroid fatty atrophy and hypopigmentation. Such changes may take up to a year to resolve, and some can be permanent changes.
Before injection therapy, consider the differential diagnosis. If a tumor or fracture is possible, radiographs should be obtained. Many times, especially with trigger-point injection (see Chapter 197, Trigger-Point Injection), x-rays are unnecessary. Other diagnoses may also be fairly straightforward and not require a prior radiographic examination either. If the diagnosis is in question or if the patient is at risk for bone metastases (e.g., a history of breast or prostate cancer), the condition should be clarified before injection therapy.
Generally, the clinician injects a combination of lidocaine with the steroid of choice. Single-dose vials of lidocaine should be used to avoid the preservative/precipitation problems (see earlier comments and the “Complications” section). Using a rather large volume of lidocaine may be beneficial. Not only does it disperse the steroid in a less concentrated solution, the volume itself may have a therapeutic effect. In some instances, only a minimal amount of lidocaine can be used (e.g., ganglion cysts, trigger fingers). In other sites, larger amounts are recommended (e.g., lidocaine 5 to 10 mL in a shoulder or knee mixed with 0.5 to 1 mL of selected steroid). A good rule of thumb is to use more, not less, when it comes to lidocaine.
Figure 192-3 Injecting finger and toe joints. A, Appropriate technique for injecting a finger joint. Tendons run over the dorsum of the finger, whereas nerves and vessels run laterally. Open the joint slightly by flexing it and then inject between the ligaments and the vascular structures as noted. The needle enters at a 45-degree angle to the joint. Any of the finger (B) and toe (C) joints may be aspirated or injected in the lateral or medial aspect. Slightly flex the joint to open the joint space. Direct the needle to enter just medial or lateral to the extensor tendon, avoiding too lateral or medial an approach where the nerve and vascular structures run. Use a 25-gauge, 1-inch needle with 0.5 to 1.0 mL 1% lidocaine and 4 to 10 mg of methylprednisolone acetate or equivalent (see Tables 192-2 and 192-5).
Figure 192-4 Trigger finger. A, The anatomy of a finger showing the annular pulleys, which maintain the flexor close to the bony structures. When the tendon becomes inflamed and enlarges, it catches on the pulleys, causing a snapping with extension or a “trigger finger.” B, Identify the flexor tendon involved. Insert the needle at the distal palmar crease. Attempt to position it peritendinously. When the needle is in position, the syringe will move with flexion of the finger. Use a 25-gauge, 1-inch needle with 0.25 to 0.5 mL 1% lidocaine and 4 to 10 mg of methylprednisolone acetate or equivalent (see Tables 192-2 and 192-5).
Figure 192-5 Wrist joint. A, Injection of the wrist joint. The hand is held in slight flexion, and the needle is inserted just distal to the radius in the “snuff box.” B, Flex the joint 20 degrees to open the joint spaces. The dorsal approach is generally used. Position the needle perpendicular to the skin surface. Enter at a site distal to the radial head and lateral to the extensor pollicis longus tendon (just ulnar to the anatomic “snuff box”). If the needle can be easily inserted to 1 or 2 cm, it is correctly positioned in the joint space. The intercarpal joints have interconnecting synovial spaces, and the contents of one correctly placed injection will disperse into the entire joint complex. Use an 18- to 20-gauge, 1- to -inch needle with 0.5 to 1.0 mL 1% lidocaine and 4 to 10 mg of methylprednisolone acetate or equivalent (see Tables 192-2 and 192-5).
Figure 192-6 A ganglion is a manifestation of joint inflammation. A, Frontal view. B, Side view. C, Example of an unusual ganglion cyst on the thenar eminence. D, Aspiration of the cyst. Hold the needle in position with the hemostat and remove the syringe. Attach the steroid-containing syringe and inject the contents. (Some have used fibrin sealants, hypertonic saline, and other irritants for attempts to “scar down” the cyst.) E, The contents are often thick, and there may only be minimal return of a gel-like material. F, Use an 18- to 20-gauge, 1- to -inch needle with 0.5 to 1.0 mL 1% lidocaine and 4 to 10 mg of methylprednisolone acetate or equivalent (see Tables 192-2 and 192-5).
(A–E, Courtesy of The Medical Procedures Center, PC, John L. Pfenninger, MD.)
Figure 192-7 De Quervain’s disease. Maximally abduct the thumb to accentuate and identify the tendon. Insert the needle parallel to (but not into) the tendon. Inject at the areas of greatest tenderness. Postinjection splinting may still be necessary. Use a 25-gauge, -inch needle with 3 to 4 mL 1% lidocaine and 10 to 20 mg of methylprednisolone acetate or equivalent (see Tables 192-2 and 192-5).