Swollen, Achey Knees? Those Are Tell-Tale Symptoms of Knee Arthritis
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About 16% of people worldwide have knee arthritis, which, if left untreated, can lead to flare-ups of pain that reduce the ability to perform even the simplest tasks. Fortunately, though, experts say there are ways to manage the condition and get back to living a pain and stiff-free life. Keep reading to learn more about knee arthritis, including types, symptoms, causes, and treatments.
What is knee arthritis?
Arthritis in general is defined as damage to cartilage, the connective tissue that cushions joints, explains Jeffrey Zarin, M.D., an orthopedic surgeon at Cedars-Sinai Kerlan-Jobe Institute.
“Think of it like an ice skating rink. The floor is slippery, so things can move around; cartilage works similarly,” Zarin adds. “When there is damage to the cartilage, things don’t move as well anymore.”
Knee arthritis specifically deals with the damage of cartilage in the knee joint area, meaning, when the knee is in use—bending down, walking, turning—bone meets bone and causes excruciating pain.
In addition to that, Zarin says busted cartilage triggers an immune response, which causes additional inflammation and leaves lingering and unpleasant side effects such as stiffness, swelling, and a constant knee ache.
Types of knee arthritis
There are a few different types of knee arthritis, but Osteoarthrits is the most common.
Osteoarthritis of the knee
Also known as “wear and tear arthritis,” Osteoarthritis is caused by damaged cartilage that happens over time. While it can affect any part of the body, it often shows up in the hands, hips, and knees.
Rheumatoid arthritis of the knee
Rheumatoid arthritis is an autoimmune disease that attacks the lining of the joints and can present within the knees, causing pain, stiffness, and swelling.
Post-traumatic knee arthritis
A type of Osteoarthritis, post-traumatic arthritis is a result of trauma to the knee, from instances like a sports-related injury or car crash.
Knee arthritis causes
There is no single cause of knee arthritis—it can happen for many different reasons. And “sometimes we just don’t know” the cause, Zarin explains. “There can be other factors that are not so obvious and unknown reasons why people’s joints suddenly wear out.”
However, some known causes of knee arthritis are:
Genetics
“Some people are just shaped in a way that needs their cartilage to wear out over time. You may not have been born with cartilage that is as durable as other people’s,” Zarin says.
Knee injury
A more common fault for knee arthritis is a past injury. A person may overuse their joint, causing cartilage to tear, or have broken a bone that gradually changed the mechanics of the knee, leading the cartilage to wear out.
“Cartilage is one of the few tissues that does not regenerate so we have to protect the cartilage we have, because it’s not something we can regrow,” warns Teja Kapoor, M.D., a rheumatologist at ColumbiaDoctors and assistant professor of medicine at Columbia University Irving Medical Center.
Torn meniscus
A torn meniscus, a common injury caused by aggressively twisting or rotating the knee, may also predispose the joint to knee osteoarthritis. Sanjeev Bhatia, M.D., an orthopedic surgeon at Northwestern Medicine Central DuPage Hospital, says the meniscus acts as a shock absorber for the knee. When it gets destroyed or severely injured, it increases the risk for knee arthritis because the knee is not as stable and no longer has the same shock absorption.
“When people develop meniscus tears, we try to do everything in our power to save that meniscus because the meniscus is helping to save the cartilage,” explains Bhatia.
Age
Osteoarthritis is an age-related disease. According to the Arthritis Foundation, symptoms often manifest in adults older than 50. Research suggests aging contributes to changes in cells and joint tissue that trigger knee arthritis. Aging increases the risk of cell death, preventing chondrocytes, cells found in cartilage tissue, from forming.
However, Kapoor notes that not everyone will experience arthritis as they age. “If older people are very active and exercise regularly, they’ll likely not experience knee osteoarthritis,” she explains. “That’s also why people in their 20s and 30s who are morbidly obese all their life and have not been exercising develop knee osteoarthritis at a young age.”
Knee arthritis risk factors
Several controllable and uncontrollable factors can affect a person’s risk for knee arthritis. For this reason, Zarin stresses that no blood or genetic test can tell you whether you’ll have premature arthritis. With that said, some risk factors are:
Obesity
People with obesity have an increased risk of knee arthritis. Excess weight—even an extra 15 to 50 pounds—creates a significant amount of stress and pressure on the joints, speeding up the damage and destruction of cartilage in your knees. The Arthritis Foundation explains that cartilage acts as a shock absorber to cushion the 1.5 pounds of force you make every time you take a step. Excess pounds on top of it all can accelerate cartilage deterioration. What’s more, obesity releases pro-inflammatory proteins, causing low-grade inflammation. Constant inflammation makes you more likely to develop osteoarthritis.
“For every one pound you lose, it’s almost taking four pounds off each knee,” adds Kapoor. “Any type of weight loss is very helpful.”
Family history of arthritis
To an extent, genetics play a small role in a person’s risk of developing knee arthritis. The Centers for Disease Control and Prevention (CDC) says that knee arthritis occurs more often in people whose relatives have it as well. Kapoor says the genetic risk is stronger if it comes from the mother’s side of the family. Additionally, the CDC says there seems to be a link between knee osteoarthritis and having a family member with osteoarthritis of the hand.
Bowleggedness
People who are born bow-legged—a condition where the bones in the knees are misaligned, leaving the knees curved outward even when the feet and ankles are together—have a greater risk of osteoarthritis because of the stress already placed on the knee. “People who are bow-legged tend to have more wear and tear on the inside parts of the knees,” explains Zarin. “As those forces over time lead to extra pressure on the knees, it can lead to wear and tear [of cartilage].”
Gender
Women have a higher risk of getting knee arthritis than men. One reason is the anatomical differences between a man and a woman. For example, women have wider hips than men, causing a “knock-kneed” position that can stress the outside of your knees. Women also have a higher risk for developing patellofemoral syndrome, where the kneecap is misaligned, causing rubbing on the thighbone. This condition can be worsened by wearing high heels, which hyper-extends the knees.
Knee arthritis symptoms
The earliest and most notable sign of knee arthritis is inflammation around the joint. For example, you may feel discomfort and swelling in the knee if you walk or run too far. However, Dr. Zarin cautions doctors cannot rule out osteoarthritis of the knee even if you don’t show evidence of inflammation.
“It’s the mystery of arthritis. Some people show no inflammation, but their X-rays show the patient’s cartilage is worn out,” he explains. In other cases, “people don’t have a lot of wear and tear of the actual cartilage, but their body really reacts aggressively.”
Bhatia recommends seeing your doctor if you start having joint pain that limits your mobile function and does not go away after two weeks. Other symptoms you may come across include:
Feeling sore, stiff, or achy knees after a physical activity
Swollen knees if you walk or run too far
Warmth on the knees
Creaking, popping, or grinding noises when moving your knee (crepitus)
Joint pain that changes based on the weather
Gradual increase in knee pain
Knee arthritis diagnosis
Your doctor will conduct a physical exam to check for signs of pain, stiffness, or swelling. They will then order X-rays for your knees to identify any mechanical problems.
After the scans, your doctors will review the X-rays, especially the space between the bone in your knee. Bhatia says if there is space, it means the meniscus is likely functioning well, and the lining of the cartilage is probably in good shape. If there’s no space between joints and the bones are touching each other, it means the cartilage has worn out on the ends of the bones.
Knee arthritis treatments
Treatment options target both the mechanical issues and inflammation triggered by knee arthritis. Non-surgical options involve:
Icing the knee immediately after exercise
Using anti-inflammatory medicines such as ibuprofen or naproxen half an hour before a long walk to prevent inflammation
Using a knee brace or other knee support like a cane to take some stress off of the knees when moving
Physical therapy
Steroid injections
Over-the-counter topical diclofenac gel, which reduces pain and swelling
Hyaluronic acid injections, which can act as a temporary joint lubricant
If you develop pain or tightness in the knees while resting, your doctor may recommend knee replacement surgery. The surgery repairs and replaces the damaged knee area with artificial cartilage that acts as a cushion to the knee joint. You may be a candidate for a partial or a total knee replacement surgery depending on how much of the surface of the knee needs repair. Because there is no more cartilage damage after a total knee replacement, Zarin says knee arthritis can technically be eliminated by it.
Knee arthritis prevention (and when to see a doctor)
Kapoor says prevention is critical when dealing with potential knee arthritis. “Your knees are a weight-bearing joint, and there’s only so much the knees can put up with before breaking down,” she adds. Keeping your muscles strong and knees flexible will help more than trying to reverse the damage.
All experts note that muscular conditioning and regular physical activity are essential. And believe it or not, running is actually recommended for people with healthy knees. “Running and jogging is not bad for your knees and can actually lead to a release of anti-inflammatory molecules,” explains Kapoor.
However, you’ll still want to take precautions when running, such as stretching beforehand, wearing appropriate shoes, and running with a support brace. If you have severe arthritis or stability problems, Zarin advises switching up your exercise routine to a low-impact activity such as bicycling, Tai Chi, or swimming.
Kapoor warns not to neglect exercises that target other parts of the body, especially the thigh muscles—because if they are weak, then the knees will have to do more work.
Last, but not least: Listen to your knees. If they hurt or swell every time you engage them, it’s a sign you should get them checked out by a doctor ASAP. An early diagnosis and intervention could prevent you from having pain while sitting or aches that wakes you up in the middle of the night.
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