Facet joint injections are a minimally invasive medical procedure used to address back pain originating from specific small joints in the spine. This technique serves both a diagnostic function, pinpointing the pain source, and a therapeutic function, providing relief from inflammation and discomfort. This targeted approach is used when conservative treatments, such as physical therapy or oral medications, have not provided adequate relief for persistent back or neck pain.
Understanding Facet Joints and Pain Sources
The facet joints, also known as zygapophyseal joints, are small, paired joints situated on either side of the vertebrae, connecting one spinal bone to the next. These joints are lined with smooth cartilage and surrounded by a joint capsule that contains lubricating synovial fluid. Their primary function is to provide stability to the spine and control the range of motion, limiting excessive twisting and backward bending.
Facet joint pain arises when these joints become irritated or inflamed. Common causes include osteoarthritis (wear and tear on the cartilage) or general degenerative changes in the spine. Injury or repetitive stress can also contribute to this inflammation, leading to a breakdown of the joint surfaces.
The symptoms are usually localized to the back or neck, often worsening with movements that compress the joints, such as standing or leaning backward. The discomfort may radiate to the buttocks and the back of the thigh, or into the shoulders and arms if the affected joints are in the neck. This pain rarely travels below the knee, which helps distinguish it from pain caused by a compressed nerve root.
The Procedure: What to Expect During the Injection
The facet joint injection procedure is performed in an outpatient setting and is highly targeted. Before the injection, patients are advised to stop taking blood-thinning medications for a specified period to minimize the risk of bleeding.
Patients are positioned, often lying face-down, and the skin over the injection site is cleansed with an antiseptic solution. A local anesthetic is administered to numb the skin and surrounding tissue, which may cause a brief stinging sensation. Fluoroscopy (a live X-ray guidance system) or CT guidance is used to ensure the needle is placed with precision into the small facet joint capsule.
Once the needle is confirmed to be in the correct position, a small amount of contrast dye is often injected to confirm the spread of the medication within the joint space. The final injection consists of a mixture, combining a long-acting corticosteroid (a powerful anti-inflammatory) and a local anesthetic, such as lidocaine or ropivacaine. The total procedure time with preparation and monitoring can be longer than the injection itself.
Post-Injection Care and Response
Immediately following the injection, patients are monitored in a recovery area for a short time, typically 20 to 30 minutes, before being discharged. A driver is mandatory, as temporary leg weakness or dizziness may occur due to the anesthetic or sedation, impairing driving ability. Patients should avoid strenuous activities for the first 24 to 48 hours following the procedure.
The initial pain relief is often the result of the local anesthetic, which takes effect almost immediately but wears off within a few hours. The original pain may return or even increase temporarily once the numbing agent dissipates. The anti-inflammatory effect of the corticosteroid is delayed, beginning to work within two to seven days after the procedure.
For diagnostic purposes, the patient is asked to track their pain levels and daily activity response in the days following the injection. Significant, though temporary, pain relief suggests that the injected facet joint was the primary source of the patient’s discomfort. This information is then used by the physician to determine the most effective strategy for long-term pain management.