A genicular nerve block is an injection-based procedure designed to manage chronic knee pain by targeting specific sensory nerves around the joint. This minimally invasive treatment interrupts the transmission of pain signals from the knee joint capsule to the brain. By blocking these signals, the procedure can offer significant temporary relief for individuals whose knee pain has not responded adequately to conventional treatments like physical therapy or oral medications. The injection serves both a diagnostic purpose, confirming the source of the pain, and a therapeutic purpose, providing a period of pain reduction.
Anatomy of Genicular Nerves
The knee joint receives sensory information through a network of small nerves known as the genicular nerves, which are branches of larger nerves like the femoral, sciatic, and obturator nerves. These nerves carry pain signals from the joint capsule to the central nervous system. Since the knee joint itself has limited sensation within its internal structures, the genicular nerves are the primary pathway for chronic pain signaling.
The most commonly targeted branches for this procedure are the superior medial, superior lateral, and inferior medial genicular nerves. These nerves travel closely alongside the genicular arteries, which often serve as anatomical landmarks for the procedure. Precisely targeting these three branches allows practitioners to effectively cover the main sensory pathways for pain originating from the front and sides of the knee joint.
The Genicular Nerve Block Procedure
The genicular nerve block is typically performed in an outpatient setting and usually takes less than an hour, including preparation and recovery time. The patient is positioned comfortably, and the skin around the knee is thoroughly cleansed with an antiseptic solution. A local anesthetic is injected first to numb the skin and underlying tissue, minimizing discomfort.
The procedure relies on live imaging guidance to ensure accurate placement of the injection. Physicians utilize fluoroscopy (real-time X-ray) or ultrasound to visualize bony landmarks and guide the fine needle to the precise target locations near the nerves. This imaging ensures the medication is delivered exactly where the genicular nerves pass over the bone.
Once the needle is correctly positioned, the medication is injected, bathing the nerve branches. The injectate typically consists of a local anesthetic, which provides immediate but short-term numbing, and sometimes a corticosteroid, which offers longer-lasting inflammation reduction and pain relief.
Indications for Genicular Nerve Blocks
A primary reason a patient might receive a genicular nerve block is for chronic pain caused by severe knee osteoarthritis, particularly when surgery is not an option or has been delayed. The procedure is also a common option for individuals experiencing persistent pain after total knee replacement surgery, known as post-arthroplasty pain. For these patients, the block offers a non-surgical alternative for managing ongoing discomfort.
The procedure has two main roles: diagnostic and therapeutic. A diagnostic block uses only a fast-acting local anesthetic; if the patient experiences significant, immediate pain relief, it confirms that the genicular nerves are the primary source of the pain. If the diagnostic block is successful, a therapeutic block may be performed later, often including a steroid for a longer-lasting effect.
Post-Procedure Recovery and Potential Outcomes
Following the injection, patients are monitored briefly before being discharged home and are advised not to drive immediately. Patients commonly experience temporary numbness or a heavy sensation in the leg due to the local anesthetic, which resolves within a few hours. Localized soreness or minor bruising at the injection sites may occur but is temporary.
Relief from a therapeutic block can vary widely, with some patients experiencing pain reduction for several weeks to months. If the initial diagnostic block confirms the nerves are the pain source and provides substantial relief, a more durable option may be recommended. This option is often genicular nerve radiofrequency ablation (RFA), which uses heat to temporarily halt the nerve’s ability to transmit pain.
As with any injection procedure, there are minor risks, including a small chance of bleeding, infection, or temporary nerve irritation. Patients who respond positively to the block are often better able to participate in physical therapy, which supports long-term functional improvement and mobility.