Raj N. Sureja, MD
As an Interventional Pain Management Physician, I treat patients with therapies designed to address their chronic pain with injection procedures as an alternative to surgery. One of the more challenging pain issues I see is chronic knee pain. Some patients have severely arthritic knees but because of health reasons, they cannot undergo the major surgery to have their arthritic knee replaced. Other patients simply choose not to do so. On the other hand, I also have patients who have had a successful knee replacement, from the viewpoint of the surgeon, where the implant was placed perfectly, there were no complications nor infection, but the patient still has severe, unexplained pain, even though the arthritis was removed. These patients are good candidate for genicular nerve blocks (GNB). In this article, I will discuss GNB, the benefits, the risks, and the results.
First, a bit about knee anatomy, so you will get a general understanding of how and why the procedure is performed. The knee is highly enervated, meaning there are many nerves and branches feeding your muscles, tendons, ligaments, and other soft tissues, telling this complex joint when to bend, straighten, twist, etc. These are the same nerves that can become hypersensitive to pain signals, and once a pain pathway becomes established to the brain, they can continue to fire pain signals even when the pain generator, such as arthritis, has been removed. For our discussion here, I will focus on the four main genicular nerves, that encompass the knee and work in concert with other large nerves of the leg to communicate with the brain.
We have found that when the genicular nerve is anesthetized, pain signals from the knee to the brain are significantly decreased if not totally resolved temporarily. This can last from 6 hours to 24 hours but has been known to last up to two days. While not a permanent pain relief solution, this provides me with a great diagnostic tool to ascertain from which nerve(s) the pain signals are being generated. We can then discuss more effective and long-lasting treatment options, such as radio frequency ablation.
The GNB is done in a procedure room in my office, under sterile conditions, using fluoroscopy. I can visualize the nerves, bones, and other tissue of the knee before injecting a local numbing medication into the skin and subcutaneous tissue. I then visualize to the bony anatomy of the knee, inject with contrast agent, and inject more anesthetic medication at the site of the nerve. The addition of cortisone (steroid medication) to the injection may prolong the relief up to 3-6 months. A band-aid is placed over the injection site and the patient is monitored for 15-20 minutes for any side effects before being allowed to go home.
Risks involved in this procedure are rare, but include: infection at the injection site, joint or vessel punctures, inadvertent anesthesia of the incorrect nerve causing temporary drop foot, or nerve damage.
You MAY SHOWER, but no baths for 24 hours. There may be temporary soreness at the injection site. I recommend icing (always with a barrier between the skin and ice) intermittently for the first 24 hours. You may also experience a headache, although this is rare. You may take Tylenol for pain. If the area becomes red, inflamed or oozes, or if you develop a fever of 100.5 degrees or more, please call our office immediately, or seek care with your PCP.