What is Knee Osteoarthritis?

Normal knee vs. knee with osteoarthritis, showing worn cartilage, bone spurs, joint space narrowing, and inflamed synovium.

“Arthritis” is an umbrella term that includes autoimmune arthritis, post-traumatic arthritis, and osteoarthritis. In general, “arthritis” simply means “wearing out”. Arthritis is a complex interplay of mechanical factors, changes in joint fluid content, inflammatory factors, and many more. Most patients have osteoarthritis, which is the general wear-and-tear that happens over a lifetime of using the joint, where the cartilage wears away causing pain and stiffness. Along with the cartilage wearing out in the knee, other structures also wear out including the meniscus. The meniscus is a “shock absorber” and “stabilizer” of the knee. Many patients come to see me with an MRI that shows tears of the meniscus. It is normal for the meniscus to be worn out with osteoarthritis.

Most patients who suffer from a worn out knee experience pain, stiffness, and limitations to normal daily activities such as putting on socks and shoes, going up and down stairs, or getting in and out of the car. Pain is usually experienced in the knee, but at times will extend down the shin. Many patients may feel the sensation of the knee “giving out”, or “locking up” and grinding.

The need for and timing of surgery should be a shared decision between you and your surgeon. Generally, you should ask yourself the question: “Is this knee affecting my ability to live the life I want to live?” If the answer is yes, then the next discussion is if non-surgical options have been attempted. Oftentimes, patients may get significant relief and avoid surgery for several years before a surgery would be needed.

As we discuss the appropriate timing for your joint replacement, we need to keep two important points in mind – 1. the pain that the worn out joint is causing, and 2. any stiffness or weakness that is occurring in and around the joint.

For the best possible outcome from a knee replacement, we want to time the surgery for when the joint is causing pain and affecting your quality of life, but ideally before the knee gets too stiff or the muscles around the knee get weak. Weakness and stiffness prolong full recovery time.