Facet joints are small spinal joints which exist along each side of the cervical, thoracic, and lumbar spines. Each joint contains cartilage, a capsule, and small nerve endings (think of a small joint like a knuckle) which can transmit pain when a facet joint becomes swollen, inflamed, degenerative, or injured.
Facet joint injections can be performed either diagnostically or for therapeutic purposes. Diagnostic injections to the facet joints can be performed in two ways. One way is by placing anesthetic into a given facet joint (intra-articular injection). The second way is by placing the same anesthetic along the nerves which supply sensation to the facet joint. These nerves are known as the medial branches (“medial branch block’).
It should be highlighted that the only means of accurately confirming pain arising from the facet joints (“facet syndrome”) is to perform one of these diagnostic injection and assess the response of the patient during the life of the injected anesthetic. Therapeutic injections to the facet joint can take the form of a steroid containing solution placed inside a facet joint. Alternatively, radiofrequency denervation can be utilized to actually burn the small nerve endings which supply sensation to a painful joint. For more information on facet injections in the non-surgical treatment of spinal pain, please click on this useful link from the North American Spine Society Patient Education Series.