Genicular Nerve Block
What is a Genicular Nerve Block?
Patients with chronic knee pain that has failed to respond to conservative care may be candidates for genicular nerve block. This procedure is based on a theory that blocking the nerve supply to a painful area may alleviate pain and restore function. The knee joint is innervated by the articular branches of various nerves, including the femoral, common peroneal, saphenous, tibial, and obturator nerves. These branches around the knee joint are known as genicular nerves. Several genicular nerves can be easily approached with a needle under fluoroscopic guidance. Patients can get a diagnostic genicular nerve block to determine if this will provide adequate relief.
Under fluoroscopic guidance, the provider will approach the target by introducing a spinal needle from either an anteroposterior or lateral entry point with the final position residing adjacent to the bone. After negative aspiration, some physicians elect to administer contrast to exclude vascular uptake, avoiding a false negative result. To conclude the procedure, 2 mL of local anesthetic is deposited on each of the superolateral, superomedial and inferomedial genicular nerves.
The most common risks associated with genicular block are:
- Misplacement of the needle.
- Unexpected bleeding.
- Drug allergy.
- Nerve damage.
- Worsening pain.
How Long Does a Genicular Nerve Block (GNB) Last?
After your injection, you will feel immediate short-term relief, lasting 8-24 hours. The temporary effects are intentional. Genicular nerve blocks are often used to test the effectiveness of a more intensive treatment, called genicular rhizotomy, also known as radio frequency ablation (RFA)
A GNB is a diagnostic procedure with local anesthetic generally conducted before making decisions regarding radiofrequency ablation. Radiofrequency ablation is a minimally invasive procedure that can provide pain relief lasting from six months to a year or more.