What Is an Intra-articular Injection?
An intra-articular injection, by definition, is an injection administered directly into a joint. The medication is actually injected into the joint space for the purpose of relieving joint pain. Corticosteroids (steroids) were the first commonly-used substances injected into painful joints. Aside from intra-articular steroid injections, there are also intra-articular hyaluronic acid injections and intra-articular local anesthetics.
When Is an Intra-articular Injection Given?
An intra-articular injection is typically given when a joint with localized pain (acute or chronic) has not responded to or stops responding to oral pain medication, oral anti-inflammatory medication, or other conservative treatment options.
ntra-articular injections have been a treatment option for decades. Intra-articular steroid injections, specifically, have been used to treat painful joints since the 1950s.
How Do the Injections Work?
Intra-articular steroid injections have anti-inflammatory properties and work by decreasing inflammation. Technically, intra-articular steroids decrease the number of lymphocytes, macrophages, and mast cells, thereby reducing phagocytosis, lysosomal enzyme release, and the release of inflammatory mediators (interleukin-1, leukotrienes, and prostaglandins). By reducing inflammatory mediators, pain is decreased too.
Some patients with non-inflammatory arthritis, such as osteoarthritis, also are helped by intra-articular steroid injections. Also, intra-articular steroids may protect joint cartilage by reducing metalloproteinase synthesis (which acts to degrade cartilage).
Hyaluronan injections are an attempt to improve the lubrication of the joint, reduce pain, and improve range of motion. When there is cartilage damage, synovial fluid changes and loses its ability to lubricate the joint.
There are at least five products now marketed as hyaluronates.
Local anesthetic injections are sometimes given with intra-articular steroid injections. They are said to provide a temporary analgesic effect on their own accord. But, according to AAOS Now from June 2010, researchers reported that intra-articular local anesthetics have a negative effect. Over time, they reduce chondrocyte (the only cells found in cartilage) density. The study included animals, though, not humans.
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Not intended as medical advice. Please consult a physician for all medical issues.