Facet joint injections are a minimally invasive procedure designed to address back or neck pain that originates from the small joints located in the spine. This targeted treatment involves injecting medication directly into or near these joints, which are a common source of chronic discomfort. When conservative treatments like physical therapy and oral medications do not provide sufficient relief, an injection can serve as both a diagnostic tool and a therapeutic intervention. This procedure offers many patients a path to improved function and reduced pain.
The Anatomy and Function of Facet Joints
The spine is composed of a column of bones called vertebrae, and the facet joints are located on the posterior side of these bones. They act like hinges, connecting adjacent vertebrae from the neck (cervical spine) down through the lower back (lumbar spine). These synovial joints are enveloped by a capsule of connective tissue and contain lubricating synovial fluid, which allows for smooth movement.
The primary function of the facet joints is to provide stability to the spine while guiding and limiting excessive motion, such as hyperextension or rotation. Each joint surface is coated with cartilage, facilitating articulation and protecting the bone ends. These joints can become a source of pain, often called facet joint syndrome, when the cartilage wears down due to age, trauma, or degenerative conditions like osteoarthritis. This degeneration leads to inflammation and irritation of the joint capsule and the tiny nerves that supply the joint, causing localized pain that may worsen with bending backward or twisting.
How Facet Joint Injections Are Performed
The facet joint injection is generally performed as an outpatient procedure in a sterile environment. The patient is positioned, typically lying on their stomach, and the skin over the target area is cleansed with an antiseptic solution. A local anesthetic is then administered to numb the skin and underlying tissue, minimizing discomfort during the needle insertion.
Image guidance, often fluoroscopy (real-time X-ray) or computed tomography (CT) scanning, is used to ensure the thin needle is placed precisely into the small facet joint space. The physician guides the needle to the correct vertebral level and joint, injecting contrast dye to confirm placement. Once the proper position is confirmed, the medication is injected, usually consisting of a local anesthetic combined with a long-acting corticosteroid. The entire injection process often takes less than 15 minutes, followed by a short observation period.
The Difference Between Diagnostic and Therapeutic Injections
Facet joint injections serve two distinct purposes, differentiated by the substances used and the intended outcome. A diagnostic injection is performed solely to confirm whether the facet joint is the source of the patient’s pain. This injection typically uses only a local anesthetic, such as lidocaine or bupivacaine, without an anti-inflammatory steroid.
Immediate pain relief, often defined as a 70% to 80% reduction, confirms that the facet joint is the pain generator. This relief lasts only as long as the anesthetic is active, usually a few hours, but guides future treatment decisions. Conversely, a therapeutic injection aims to provide long-lasting pain relief by reducing inflammation within the joint capsule. This type includes a corticosteroid, a powerful anti-inflammatory agent, mixed with the local anesthetic. While the anesthetic provides temporary relief, the corticosteroid reduces underlying inflammation over a longer period, with effects that may take several days to become noticeable.
Preparing for the Procedure and Post-Injection Care
Preparation for a facet joint injection involves several steps to ensure patient safety and efficacy. Patients are advised to stop taking blood-thinning medications, such as aspirin or certain non-steroidal anti-inflammatory drugs, several days before the procedure to minimize bleeding risk. If sedation is used, or due to temporary numbness from the anesthetic, patients must arrange for someone to drive them home, as operating a vehicle is unsafe immediately afterward.
On the day of the procedure, patients should follow specific instructions regarding fasting if sedation is planned. After the injection, patients are monitored for 20 to 30 minutes in a recovery area before being discharged. It is common to experience temporary numbness or an increase in localized soreness at the injection site, which can be managed with ice.
Patients are advised to take it easy for the remainder of the day, avoiding strenuous activities, heavy lifting, and soaking in baths or pools for at least 24 hours. The local anesthetic provides initial, rapid pain relief, but this effect wears off quickly. The therapeutic benefit from the corticosteroid often takes between two and seven days to begin, as the medication needs time to reduce the joint inflammation.
Pain relief from a therapeutic injection can vary widely, potentially lasting for several months or longer. Minor side effects include temporary pain at the injection site or a slight increase in blood sugar for diabetic patients. Serious complications like infection or nerve injury are rare due to the use of image guidance. The duration of relief determines whether repeat injections are needed or if other long-term solutions, such as radiofrequency ablation, should be considered.