Chronic knee pain treated with Genicular Nerve Block
What is the Genicular Nerve Block?
Patients with chronic knee pain that has failed to respond to conservative care may be candidates for a 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.
A Genicular nerve block is a procedure where these nerves are anesthetized (“blocked”) with local anesthetic injected through small needles. The procedure is performed with live x-ray guidance (fluoroscopy) to ensure proper needle placement. It generally takes 5 to 10 minutes for the procedure.
How is the Genicular Nerve Blockade performed?
These injections are performed under fluoroscopy guidance. A small amount of local anaesthetic (1-2ml) of lidocaine or bupivacaine is injected around the superior lateral (SL), superior medial (SM) and the inferior medial (IM) branches. A response is considered positive if there is at least 50% reduction in pain in the 24hrs following injection.
Are there any risks associated with this procedure?
Complications are rare, particularly if injections are performed using a precise needle-positioning technique. Septic arthritis can be avoided with appropriate aseptic precautions. Severe allergic reactions to local anaesthetics are uncommon. Post-procedural pain flare-up is not uncommon, and may be treated with painkillers. Neurological complications including paraesthesia and numbness have been described but are extremely rare. Radiofrequency treatment can cause patchy numbness of the overlying skin. Incidence of infection is low as the procedure is performed under strict aseptic conditions and the injections are extra articular.
Where can I get more information?
The Pain Specialists at Pain Matrix will have a very detailed discussion with the patient prior to consideration of this technique and patients are provided with resources including DVDs to give further information. It is generally a very small number of patients will benefit from this technique and therefore selection is of utmost importance.
In the case of numbness, which has not gone away after 24 hours or any loss of control over bladder or bowel, you should contact Pain Matrix or attend an Emergency Department and ask that they contact us if it is after hours.
Please make sure you have made a follow-up appointment with your Pain Specialist. You should ring Pain Matrix following your procedure if one has not already been arranged.