Knee Arthritis: Care and Considerations

Knee Arthritis: Care and Considerations

Thanks for tuning in to OrthoPedia for an overview on knee arthritis and the care and consideration surrounding its management. We will discuss what causes knee arthritis, how it affects patients, and some conservative and surgical options to get patients back to pain-free motion and activity.

Before discussing all of that, let´s touch on the anatomy of the knee so you can understand what can be a pain generator and what physicians are evaluating during office visits. The knee joint is made up of three bones. The femur or thigh bone. The tibia or shin bone, and the patella or kneecap. The fibula is a fourth bone around the knee but is not involved in the functions of the intra-articular knee joint itself. It is an attachment site for ligaments around the knee and adds to the stability of the knee, but, today, we are going to focus on the inner joint space of the knee itself.

Physicians will order x-rays to evaluate these bones and associated structures at times. This is a healthy-appearing knee joint. Just like the illustration before, you can see the femur, tibia, and patella. All the edges of the bones are smooth, and we see proper spacing in between the bones, representing healthy cartilage, which lines the end of each joint. This cartilage is called articular cartilage. When healthy, this cartilage allows for friction-free joint mobility. Two cartilage surfaces gliding together with joint fluid as lubrication are smoother than ice on ice.

There are different types of cartilages within the knee. The articular cartilage is the hard and protective cartilage on the end of the bones that is made up of mostly water. The meniscus cartilage is a more rubbery, mobile cartilage that provides stability and absorbs shock. Over time, these cartilage types can become damaged by either injury or just plain degeneration. In this image, you can see how the healthy cartilage and preserved joint space is now worn down. The cushion of the cartilage and the meniscus is gone and the bones are rubbing together, causing the knee to become malaligned with bone spurs forming called osteophytes. All these changes lead to pain and dysfunction within the knee.

Within the joint are a few other key structures that also help with joint stability. The ACL, or anterior cruciate ligament, is a well-known structure that helps keep the tibia from gliding too far forward from the femur during walking, pivoting, and cutting motions. The PCL, or posterior cruciate ligament, counteracts the ACL by not letting the tibia slide too far backwards. The medial and lateral meniscus are those disk like, soft cartilage structures that help with stability and also absorb shock. Injury to any of these key components of the knee can cause instability and ultimately, pain, which makes it difficult to enjoy those daily walks on the beach or other activities in your life.

Going back to x-rays for a moment, we can see on the left there is a nice open space between the bones. At 2 to 3 years, we start to see narrowing of that space and small bony spurs called osteophytes forming. As the arthritis progresses, we can see that the joint space on the inside portion of the knee is gone, and we have the classic bone-on-bone appearance. Now, this timeline is not the same for everyone. Sometimes it is a little faster and sometimes it is a little slower progression depending on the amount of injury or activity for each patient.

Symptoms of knee pathology can be very specific, but also at times vague. Pain with prolonged activity that is better with rest, but also sometimes rest can cause more pain due to stiffness. Loss of motion of the knee can be due to pain or mechanical changes in the knee. Tenderness around the knee is another symptom, and injuries to the ACL and meniscus can cause swelling effusions and like we said before, instability. Decreased activities can also be a symptom. The patients cannot walk as far as they used to play as many holes of golf, or maybe shop as long in the mall as they would like. Mood changes or a depressed mood, depending on the level of arthritis, is also a common complaint that we hear when interviewing a patient with advanced knee arthritis.

When patients have mild to moderate degenerative knee disease and symptoms that match, they can try non-surgical options to help with the pain on a daily basis and make activities more tolerable. Activity modification, weight loss, walking aids such as a cane or walker, over-the-counter or prescription medication for pain, bracing of the knee joint, and injections, just to name a few of those conservative measures.

Injections come in a few forms. Steroids, which can provide more rapid relief but have been shown to be detrimental to the joint over time or after repeated or consistent use. Hyaluronic acid, which are the lubricating injections that you may hear about, and then other joint therapies that use your body's own blood and cells to improve symptoms or heal an injury. Hyaluronic acid treatment helps improve the quality of your natural joint fluid environment, and thus lubricating the joint and improving your symptoms. Your doctor or surgeon can administer these through a series of injections spaced appropriately apart. This is a great non-surgical option when the cartilage degeneration is in a mild to moderate form.

If conservative options are not providing enough relief at times, a surgeon may recommend a clean out of the knee. This typically means they are going to perform an arthroscopic surgery using a small camera and instrumentation to try to rid the knee of any loose cartilage, floating debris, or small meniscus tearing. These procedures do not put any cartilage back or resurface the joint in any way, but the hope is that they can improve symptoms enough to get back to daily activities or prolong any need for a larger, longer or more involved surgery like a knee replacement. You can see in these arthroscopic images how the nice smooth white cartilage that should look like freshly plowed snow has multiple areas of damage that now look like cracks in ice, or what some term a crab meat appearance.

As we mentioned before. Arthritis is a disease of the articular cartilage in the knee, and if those cartilage defects are smaller or more localized, sometimes your surgeon can recommend a graft for those smaller areas through an arthroscopic or small open procedure. The surgeon will use allograft cartilage at times, or allograft bone, which is from a donor, or sometimes autograft cartilage, where they take cartilage from good areas of your knee and transplant it into the defective areas where your knee is missing cartilage.

We can also now harvest cartilage from non-weight bearing areas around the knee and collect it in specialized tissue collectors. We then mix that with donor cartilage and autologous fluid from your own body, like blood or bone marrow, and reimplant that cartilage mixture into the knee at the site of the deficient native cartilage.

If the area of degeneration is on the femur or the thigh bone and it is a little larger, there are procedures like the BioUni. This is a bone and cartilage graft that the surgeon implants into the area of that large cartilage defect. This procedure used to necessitate multiple small grafts that could be unstable after surgery or difficult to implant. The BioUni is an alternative to metal and plastic implants and is ideal for when the majority of the cartilage degeneration is on the femur side of the knee, but the tibia and other components of the knee are free from degeneration.

Unfortunately, sometimes there is degeneration on the tibia as well, and that can be advanced. At that time, a decision needs to be made between a partial or total knee replacement. A partial knee is ideal for when the degeneration is captured in only one compartment or one side of the knee, whereas a total knee resurfaces the entire knee.

If the patient can pinpoint the knee symptoms to a specific area, maybe using one finger to point to, and that corresponds with the majority of the arthritis, then that patient could be a strong candidate for a partial replacement. This procedure maintains the ligaments in the knee and covers the problem areas with metal and plastic.

If the arthritis in the knee is in multiple areas, meaning the inside, outside, and potentially underneath the kneecap, a total knee replacement is then more appropriate. In a total knee replacement, metal and plastic is used to cover all the areas of arthritis and a plastic spacer is placed between the metal femur and metal tibial implants to act as new cartilage and become the new walking surface.

Depending on the patient's level of activity prior to surgery and the type of surgery they have had, the rehab process can vary. The short-term goals of rehab are to decrease pain and swelling, slowly increase the knee's range of motion, and get back to unassisted walking. Long term, the goal is to have patients return to their exercise activities and increase as tolerated.

The journey to a total knee replacement can be a long one, and we hope to delay or even avoid those types of surgeries by treating injuries like meniscal and ACL tearing early in the process and in more minimally invasive ways. We are working hard to slow the progression of knee disease and injury through joint-preserving strategies rather than joint replacement, but when necessary, knee replacement is a very good option to restore the joint. The goal is to keep you mobile and pain-free for as long as possible, so you can not only walk on the beach but hit the ground running. Thank you.