Corticosteroid Injections

The knee joint is enclosed within a fibrous capsule. Because of this, a corticosteroid injected anywhere within the joint space will disperse throughout the joint regardless of where the needle enters, as long as it passes through the capsule wall. Typically, one to two cubic centimeters of corticosteroid solution are used per treatment. Orthopedic surgeons use different techniques and approaches based on their training and the patient’s anatomy. A topical cooling spray is often applied to numb the skin before needle insertion. Ultrasound guidance may or may not be used to assist with needle placement.

The two most common entry points are:

Superolateral approach (above and to the outside of the kneecap)

The patient lies on the table with the knee nearly or fully extended, often with a small pad placed beneath the joint to encourage muscle relaxation.

Anterolateral and anteromedial approaches (below the kneecap, to the outside or inside of the patellar tendon)

The patient sits with the knee bent to approximately 90 degrees. This position opens the joint space and can make needle entry more straightforward.

The corticosteroid typically begins working within a few days, so patience is important. You may notice immediate relief upon leaving the office, but this is usually attributable to the local anesthetic (such as lidocaine or bupivacaine) included in the injection, not the steroid itself. That numbing effect generally wears off within a few hours, before the anti-inflammatory action of the steroid takes effect. It is not unusual to experience a short-lived increase in pain the day following the injection, known as a “steroid flare.” Avoid overexerting the joint in the days immediately after treatment.

Corticosteroid and anesthetic injections can also serve a diagnostic purpose. The nerve fibers within the knee are not as precisely localized as those in the fingers. If the pain originates from inside the joint, complete or near-complete relief should occur during the anesthetic phase of the injection. If there is little or no improvement, the source of pain may lie outside the joint, such as in the surrounding muscles, tendons, or skin, and further evaluation may be needed.

Corticosteroids act faster than other biologic injection options, but their effects are typically time-limited, generally lasting four to eight weeks. Icing the joint after the injection and reducing impact-loading activities—favoring swimming, cycling, or an elliptical trainer over running or jumping—may help extend the benefit. When administered with sufficient time between treatments, typically at least three to four months, corticosteroid injections are generally considered safe.

Potential side effects include temporary joint irritation (redness, warmth, and discomfort), a transient elevation in blood sugar (an important consideration for patients with diabetes), and, in rare cases, localized thinning of bone tissue. If symptoms do not improve after two or three injections, alternative treatment approaches should be considered.