The knee is a hinge joint.
When working properly, the knee allows the leg to move and bend freely. That also means that a lot hinges on a healthy knee.
Walking, running, sitting, kneeling, jumping, kicking, squatting and other ordinary activities we often take for granted all depend on smoothly functioning knee joints.
But of course all of that movement inevitably wears on the knee joint. Cartilage, the smooth tissue covering that protects the bone, can degrade and tear, eventually leading to osteoarthritis. This severe breakdown of cartilage produces pain and stiffness – and limits to varying degrees all those activities that hinge on healthy knees.
Osteoarthritis of the knee is a source of suffering for some 14 million Americans. The standard treatments include over-the-counter and prescription medications, joint injections, physical therapy, braces, and in the most severe cases, total or partial knee replacement surgery. Other advanced surgical options include needle arthroscopy – a minimally invasive procedure to assess the extent of damaged cartilage – and donor cartilage and bone transplant.
Now another method of treating knee pain is set to debut at UCHealth. The minimally invasive procedure, genicular artery embolization, aims to alleviate knee pain by targeting and reducing inflammation in the joint.
Target: inflammation in the knee joint
Genicular artery embolization is a relatively new way of approaching persistent knee pain, said Dr. Leigh Casadaban, a vascular and interventional radiologist who practices at the UCHealth Radiology Clinic on the Anschutz Medical Campus.
“We often think of osteoarthritis as a wear-and-tear disease” that degrades cartilage and leads to bone-on-bone grinding, Casadaban said. “That is what we have always conventionally thought of as the cause of the pain. But newer data suggest that in addition to that, the pain source is probably inflammation.” The inflammation likely contributes to the degeneration of the joint, she added.
The idea behind genicular artery embolization is that decreasing the blood supply to damaged areas of the joint will reduce inflammation and thereby decrease pain. A study of 40 patients with varying degrees of knee pain led by UCLA Medical Center Interventional Radiologist Dr. Siddharth Padia showed that after 12 months, genicular artery embolization had reduced pain and other symptoms, like stiffness and problems with gait, in 70% of patients. These patients had tried other treatments, like injections, without success and either were not candidates for knee replacement surgery or had decided against having it.
Catheters deliver blood flow-blocking beads
How does it work? It’s an outpatient procedure performed under conscious sedation, said Casadaban, who learned and performed it at UCLA before coming to UCHealth last August. The interventional radiology team makes a pinole incision in the crease of the leg and threads a small catheter through the femoral artery. Guided by 3D imaging and contrast, the team reaches and enters the genicular arteries, which supply blood to the knee joint. (There are seven such arteries; the procedure treats from one to three, depending on the case, Casadaban said.)
The conscious patient identifies the specific areas of pain in the joint. As a further aid for identifying the correct artery, the team places a radiopaque marker – one that blocks X-rays – at each of those pain sources. The marker helps the team ensure that the identified spot is getting heavier than normal blood flow, the tell-tale sign of inflammation.
Having pinpointed those areas, the team enters the artery and deploys small beads that restrict, or embolize, the blood flow to the abnormal areas of the joint. The blood vessels remain intact, Casadaban noted.
Quick trip home after genicular artery embolization procedure
The procedure itself generally takes about two hours, Casadaban said, then patients stay for observation to make sure there are no problems before going home the same day. They have to take it easy for a few days, but require no further treatment, she added.
Prior to the UCLA trial, investigators studied genicular artery embolization in Japan, in 2014, and subsequently in Korea and North Carolina. On the strength of the research, the FDA last October granted “breakthrough device status” for the “microspheres” used to block blood flow to the genicular arteries.
Casadaban noted that half of the patients who completed Padia’s trial suffered debilitating, bone-on-bone pain. They too garnered positive results from the embolization procedure, although she added that a systematic review she co-authored in 2020 indicated that patients with mild to moderate disease enjoyed a more “durable” benefit – from six months to four years out from surgery. She looks forward to further studies of patients with more serious disease.
“We’re still learning about the disease process, but we think, based on this newest trial data, that the procedure actually can benefit patients with the most severe forms of bone disease,” Casadaban said. Padia also stated in an article for UCLA Health that genicular artery embolization “has been shown to markedly reduce the need for opioids.”
Genicular artery embolization offers one more option to treat knee pain
Patients undergoing genicular artery embolization have had no significant post-procedure problems, Casadaban said. The most common issues were pain, numbness and skin discoloration of the knee, as well as bruising at the puncture site, but “all symptoms resolved over time,” she said.
The ideal candidates for genicular artery embolization at UCHealth are those who have had persistent knee pain for at least four to six months, Casadaban said. They should have tried, without success, at least one other treatment option, such as physical therapy, NSAIDS (anti-inflammatory medications) or injections. They must not smoke, as that impedes wound healing, increases the risk of infection and over time hardens arteries. She stressed that whether or not the procedure provides relief, patients can always opt for knee replacement.
“You always have that option,” Casadaban said.
Patients should carefully consider their own situation before considering any procedure, including genicular artery embolization, she concluded.
“Every intervention has a risk,” she said. “If you can live with your knee pain, don’t take on additional risk. However, if the pain is interfering with your life on a day-to-day basis – let’s say you can only walk a few blocks or can’t do some activity you want – I think this is a good minimally invasive option before choosing surgery.”
Patients interested in learning more about genicular artery embolization should reach out to their primary care doctor for referral to Interventional Radiology at UCHealth University of Colorado Hospital on the Anschutz Medical Campus or self-refer by calling 720-848-5300 to set up a consultation.