What is knee arthritis?
Knee arthritis encompasses a large spectrum of different diseases that cause degeneration of the structures of the knee and affect function of the joint. As the structures of the knee are damaged by arthritis, patients can experience symptoms such as: pain, stiffness, swelling, instability.
Anatomy of the Knee
The function of the knee is to act like a hinge, allowing us to move our legs while walking upright. The knee joint is composed of four bones: the femur (thigh bone), the tibia (shin bone), the patella (kneecap), and the fibula. The femur and tibia are the two largest bones that make up the hinge-portion of the knee. The patella (or kneecap) is the bone that sits in the front of our knee. The patella functions like a pulley, making it easier for our muscles to move the knee joint when walking, running, or any other activity that involves our legs. The fibula is a thin bone on the outside of the leg, below the knee.
The ends of the femur and tibia that make up the actual joint surface are covered in a thick layer of cartilage. Cartilage is a smooth soft tissue the lines the ends of the bones that make up our joints. This cartilage layer is what protects the ends of the bone and allows us to move our joints without pain.
Ligaments are elastic connective tissues that connect two bones and keep the bones from separating. Ligaments help stabilize the knee joint while we are moving our knee through its normal motion.
Tendons are also elastic connective tissues, but the connect muscles directly to bone. Tendons allow our muscles to move our joints, by transferring the force of muscle contraction across a joint.
The meniscus is a ring of elastic tissue that sits between the bones. It can be thought of similar to a shock-absorber, but also helps guide the bones along each other through joint motion and stabilizes the knee joint.
Types of Knee Arthritis
Osteoarthritis – “wear-and-tear” of the knee that causes degeneration of the structures of the knee over a lifetime of activity. This is also known commonly as “degenerative arthritis.” Osteoarthritis is related to activity and can be made worse by obesity. Increased forces through our joints (either by high-impact activity or extra body weight from obesity) can damage the tissues in the knee and contribute to accelerated degeneration. Osteoarthritis does exhibit some genetic pre-disposition, and patients with family members who have osteoarthritis have a higher risk of developing it in their lifetime.
Rheumatoid arthritis – is a condition where joint damage occurs when our own immune system attacks the tissues that compose our joints. This is different from osteoarthritis, as the immune system can continue to damage your joints, even without high-impact activity. Rheumatoid arthritis typically is treated with medications that aim to decrease the immune system’s ability to damage joint tissues.
Post-traumatic arthritis – is a unique situation where an injury to the parts of the knee (bones, ligaments, cartilage, etc) leads to uneven distribution of forces within the joints. These uneven forces can damage the tissues of the joint and lead to “wear-and-tear,” much like osteoarthritis. An example is a broken bone around a joint that heals out of place and leads to alteration of the joint forces, causing further damage.
Symptoms
Despite the different varieties of knee arthritis, many of them share similar symptoms. People with knee arthritis may experience knee pain, stiffness that worsens over time, swelling that makes movement painful/difficult, painful clicking.
Post-traumatic arthritis occurs in relation to another distinct injury and usually worsens over time. Some patients may notice joint deformity.
Rheumatoid arthritis will typically involve multiple joints and commonly affects the hands and feet. Also, patients are more likely to experience morning stiffness.
Diagnosis
Orthopedic practitioners are adept at diagnosing knee arthritis. From a combination of obtaining a patient’s history, examining the affected joints for stiffness/tenderness/swelling/stability, we can typically arrive at a suspected diagnosis of knee arthritis. In order to confirm, basic X-rays are the test of choice to look for degeneration of the knee. In some instances, more advanced imaging such as ultrasound or MRI may be necessary to confirm a diagnosis. Ultimately, putting the whole picture together with history, examination, and imaging will allow your orthopedic practitioner to determine a diagnosis and recommend appropriate treatment.
Management & Treatment
Non-surgical
- Activity – remaining active helps decrease swelling, keeps muscles strong, and avoids stiffness. Commonly, the worry is: “Will I make my knee worse?” Activity is good even despite knee arthritis. It is very unlikely that activity will hurt your knee or worsen knee arthritis and activity is important for joint health.
- Weight-loss – even small decreases in body weight will greatly decrease forces that an arthritic knee experiences. These decreases in body weight will greatly decrease pain, decrease swelling, and improve overall function. Additionally, if surgery becomes an option, ideal body weight greatly decreases the risks associated with surgical treatment of knee arthritis.
- Bracing – certain braces can help the knee feel more stable. In patients with “bow-legged” or “knock-kneed” deformities, braces can help straighten the leg and decrease pain due to un-even loading of the arthritic knee joint.
- Physical Therapy – directed physical therapy can help reduce pain, strengthen muscles, and improve range of motion in the case of knee stiffness. A relationship with your therapist can be very helpful in improving your function and decreasing pain associated with knee arthritis.
- Non-steroidal Anti-Inflammatory Drugs (NSAIDs) – these are safe, non-addictive medications that help to decrease pain and swelling in knee arthritis. There are specific medications that have safer side-effect profiles compared to over-the-counter ibuprofen or naproxen (Aleve). In certain instances, these medications may not be recommended, such as in cases involving those with kidney disease, using blood thinners, and history of stomach ulcer/inflammation.
- Corticosteroid Injections – an injection of steroid into the knee joint can significantly decrease pain and swelling. These injections are typically used for temporary pain relief. Sometimes, pain relief can last for months. More commonly, they wear off over time. If repeated at certain intervals, corticosteroid injections can be a practical treatment for knee arthritis.
- Viscosupplementation – an injection of lubricating anti-inflammatory gel that is made of the lubricating proteins found within our joints. Some patients get good prolonged pain relief with these injections and they are safe.
- Platelet-Rich Plasma – this is an injection into the knee joint of proteins from your own blood. This requires drawing a small volume of your own blood that is then processed into a safe injection of your own anti-inflammatory blood proteins. Some studies have shown improvements in pain and swelling in knee arthritis.
- Stem Cells – while multiple research studies continue to find a way to regenerate healthy cartilage from stem cells, no definitive reproducible method has been identified.
Surgical
- Arthroscopy – this surgical procedure is performed through small incisions where a camera and tools are introduced into the knee. While this procedure alone is not a reliable treatment for knee arthritis, it can be an appropriate treatment for certain injuries, such as meniscal tears.
- Joint Replacement – joint replacement is a definitive long-lasting treatment for knee arthritis that has not improved with other conservative treatments. While there are always risks associated with surgery, joint replacement is a safe procedure when performed by well-trained surgeons. Joint replacement reliably improves/eliminates knee pain, improves function, and overall improves patients’ quality of life.
Recovery
Recovery after knee arthritis surgery is predictable and has improved drastically over the last decade. After surgery, patients are walking the same day. Improvements in pain management have led to decreased severity and length of post-operative pain. These pain management protocols also safely and effectively limit the use of narcotics, avoiding risks that are associated with them. Patients are commonly returning home immediately after surgery. It is rare that a stay in a rehab facility or nursing home is warranted. Physical therapy is an important part of recovery, allowing patients to improve their pain, increase motion of the knee, decrease swelling, and improve muscle strength. Physical therapy starts quickly after surgery, and varies in duration, depending on surgery type. The recovery after an arthroscopic procedure is typically quicker than a joint replacement. Most patients see significant improvement in the first few weeks and for joint replacement, a gradual improvement is seen as time goes on in the recovery period. Typically, patients will have the vast majority of their recovery by 2-3 months after the procedure.
Links: AAOS Information on Biologics: https://orthoinfo.aaos.org/en/treatment/orthobiologics-faq/
