Genicular Artery Embolization
Genicular artery embolization (GAE) is a minimally-invasive, non-surgical outpatient procedure performed by an interventional radiologist for patients with knee pain related to Osteoarthritis and Hemarthrosis (bleeding into the knee joint). For patients suffering from localized knee pain who are not responding to conservative treatments like physical therapy, weight loss, knee bracing, and medical treatment with non-steroidal anti-inflammatory drugs (NSAIDs), GAE may provide durable pain relief that lasts 6 to 24 months.
An alternative to repeated joint injections, GAE specifically targets sites of inflammation in the knee joint with the goal of treating pain as well as slowing down the ongoing process of joint destruction. Genicular Artery Embolization provides a much-needed option for patients who are not candidates for knee surgery due to other health conditions. As well, GAE may also enable younger patients to delay surgical knee replacement until absolutely necessary, helping prevent the need for revision surgery later in life.
Osteoarthritis of the Knee
Osteoarthritis (OA) is a degenerative joint disease affecting up to 32.5 million Americans. A disabling condition that causes pain, swelling, stiffness, and poor range of motion in the knees, hips, and hands, osteoarthritis of the knee is the most common, affecting 10-15% of adults.
Symptoms of Knee Osteoarthritis
- Focal knee pain, particularly with increased activity
- Swelling
- Stiffness
- Warmth
- Decreased range of motion
What Causes Knee Osteoarthritis?
Risk factors for developing knee OA include obesity, prior knee injury, repetitive use of the knee joint, age, and muscle weakness. Although “wear and tear” is a major factor causing this type of arthritis in the knee, we now know that osteoarthritis is more complex.
In addition to stress-induced damage to the cartilage in the knee, there is also inflammation, swelling, and new blood vessel formation in the knee capsule (or synovium) which release inflammatory factors (cytokines, nitric oxide [NO], and prostaglandins) that lead to a cycle of more inflammation, thickening of the capsule, and more small blood vessel formation. This cycle is also responsible for the further destruction of the cartilage and underlying bone within the knee joint. As well, inflammation also causes the formation of new sensory nerve endings and worsening knee pain.
What Are the 4 Stages of Knee Osteoarthritis?
- Doubtful – minimum disruption, 10% of cartilage is lost.
- Mild – joint-space narrowing; the cartilage begins breaking down, and osteophytes occur.
- Moderate joint-space reduction; gaps in the cartilage expand until they reach the bone.
- Severe – joint-space greatly reduced; 60% of the cartilage is lost, and large osteoarthritis presents.
How Is It Treated?
Initial treatment for Osteoarthritis of the Knee recommended by the American Academy of Orthopedic Surgery includes weight loss and low-impact aerobic exercises focused on strengthening the knee. In addition, pain-relievers with anti-inflammatory capabilities (NSAIDs like ibuprofen and naproxen) are also used to help with the pain and reduce the cycle of knee inflammation.
Steroid injections can also provide some relief, although there has been concern that repeated knee injections can potentially cause further destruction of the knee joint. A recent study published in the New England Journal of Medicine (Deyle, 2020) showed that a year of physical therapy provided better pain relief than steroid injections, however, PT can be time-consuming, expensive, and difficult to schedule.
Genicular artery embolization or GAE provides another option for patients who are no longer getting relief from conservative measures and are either not a good candidate for surgery or are hoping to delay knee replacement until necessary. Although total knee replacement is a safe and effective treatment for moderate to severe osteoarthritis of the knee, there are advantages to waiting until the right time for surgery. Patients who have knee surgery at a young age are more susceptible to eventual loosening of the hardware, which requires repeat surgery.
How Does GAE Work To Treat Osteoarthritis Of The Knee?
Genicular artery embolization is an outpatient, non-surgical procedure that targets the sites of inflammation in the knee joint. The thickened capsule or synovium around the knee joint is the site of inflammation, where new blood vessels and sensory nerve endings are forming.
Embolization, a well-established medical procedure, uses small beads that block the blood supply to these areas of the thickened capsule. Limiting the blood flow to these areas calms the inflammation and slows the cycle of further joint destruction by preventing the release of more inflammatory factors (cytokines, NO, and prostaglandins). At the same time, the painful nerve endings are deadened, leading to much-needed pain relief. Although not a permanent solution,
Genicular artery embolization can offer 6 to 24 months of durable pain relief. Repeat treatment may be an option for some patients. In combination with other conservative treatments, GAE can be a safe and effective treatment for patients awaiting knee replacement or for those who are not a candidate for surgery.
Hemarthrosis of the Knee
Another cause of a painful, warm, swollen knee with a limited range of motion, hemarthrosis refers to bleeding within the joint. Bleeding may be related to a number of causes including a traumatic knee injury, post-operative bleeding following an invasive procedure or surgery, bleeding disorders like hemophilia and inherited coagulation factor deficiencies, and complications of blood thinner medications. Blood within the joint can lead to inflammation and a cycle of joint damage similar to osteoarthritis. Blood in the joint may also have direct toxic effects like cartilage and bone destruction.
Identifying the cause of the bleeding is important for deciding the appropriate treatment. Traumatic injuries and post-operative bleeding sometimes require surgery. Patients with bleeding disorders or bleeding related to blood thinners may require certain medications tailored to their condition.
In either case, ongoing or recurrent bleeding into the knee can be treated with genicular artery embolization as an alternative to surgery in certain cases. This minimally invasive procedure targets the source of the bleeding to prevent further blood from accumulating in the knee joint. As well, GAE targets associated inflammation of the joint capsule to reduce the risk of further joint destruction, just as in the case of patients with osteoarthritis.
Clinical Evaluation of Hemarthrosis
Most patients will seek initial evaluation for their knee pain with an orthopedic physician specializing in orthopedic surgery or sports medicine. Imaging of the knee will typically start with x-rays to look for signs of joint damage. More advanced imaging with CT or MRI may be ordered for a more detailed evaluation of the bone structure, ligaments, cartilage surfaces, and joint capsule (or synovium). Lab tests and joint aspiration may be used to evaluate for other joint conditions.
How Is Knee Hemarthrosis Treated?
Depending on the condition and severity of the knee pain, treatment options will range from conservative management (physical therapy, knee bracing, weight loss, and NSAIDs) to steroid injections to genicular artery embolization to surgery, including total knee replacement.
Genicular artery embolization may be an appropriate treatment option for patients with Osteoarthritis or Hemarthrosis of the knee, who are:
- Not responding to conservative treatment options
- Not good surgical candidates
- Hoping to delay eventual surgical treatment with partial or total knee replacement
If you would like to request a consultation with Dr. Ermentrout for Genicular Artery Embolization please call the Atlanta Interventional Institute at 770-771-6617.
How Is GAE Performed?
Genicular artery embolization is a minimally invasive outpatient procedure performed by an interventional radiologist. Twilight sedation and local numbing medication are given during the procedure to keep the patient comfortable.
- A tiny catheter, which is a small hollow tube the size of a piece of spaghetti, is placed in an artery at the top of the leg using ultrasound guidance.
- The catheter is then advanced toward the knee using a state-of-the-art x-ray guidance system. The blood vessels of the knee are mapped using this same x-ray system, enabling the doctor to identify areas of abnormal blood supply around the capsule of the knee.
- Then, an even smaller microcatheter is advanced into the arteries of the knee that will be treated, usually between 1 and 3 small genicular artery branches.
- Embolization, or infusion of small beads, is then performed to gently reduce the blood flow to the abnormal areas of the thickened joint capsule (or synovium).
- At the conclusion of the procedure, the catheters are removed and the access into the artery is closed, with just a small band-aid at the skin surface.
Recovery after the procedure is approximately 2 hours in the clinic. Pain relief may be felt as soon as 3 days after the procedure, but results are expected for most patients within 2-4 weeks.
Clinical Results of GAE
For patients with Hemarthrosis of the knee, genicular artery embolization provides a minimally-invasive alternative to surgery. There is close to 100% technical success at identifying the source of ongoing bleeding in the knee and stopping the bleeding. GAE has been a long-established treatment for hemarthrosis. Additional benefits include reduction of knee inflammation and pain and reduction in the risk of repeat bleeding with the knee.
For patients with moderate to severe Osteoarthritis of the knee who have not had adequate pain relief from conservative management, GAE provided significant pain relief with benefits as soon as three days after the procedure. Average pain scores decreased from 8 out of 10 before GAE to 3 out of 10 within the first week. Overall, there was an average of 61% reduction in pain metrics with sustained pain relief at 12 months in 96% of patients (Padia et al 2021).
FAQs about Genicular Artery Embolization
Am I a good candidate for Genicular Artery Embolization?
Genicular Artery Embolization may be an appropriate treatment option for patients with Osteoarthritis or Hemarthrosis of the knee, who are:
- Not responding to conservative treatment options
- Not good surgical candidates
- Hoping to delay eventual surgical treatment with partial or total knee replacement
Will I still need a partial or total knee replacement?
Genicular Artery Embolization can provide sustained pain relief for many patients with knee pain due to hemarthrosis and osteoarthritis who have not responded to other treatments. Many patients may still benefit from eventual knee surgery, however, delaying surgery until the optimal time can have significant benefits, including reducing the odds of requiring a second surgery later in life. The decision to proceed to knee surgery will be up to you and your orthopedic surgeon, however, we will work with you and your surgeon to help keep you on a plan for optimal knee function and pain relief.
Is Genicular Artery Embolization a new procedure?
Embolization procedures like this have been performed by interventional radiologists for more than 50 years to treat a variety of conditions. As such, genicular artery embolization has been a long-established method of treating bleeding in the knee for patients with recurrent hemarthrosis. Over the past 10 years, leading interventional radiologists in Japan and the United States have demonstrated that the GAE procedure is safe and effective and provides durable pain relief to patients with moderate to severe osteoarthritis.
If you would like to request a consultation with Dr. Ermentrout for genicular artery embolization, please call the Atlanta Interventional Institute at 770-771-6617.
