Arthritis
Two types of arthritis can affect the knee: Osteoarthritis and Inflammatory Arthritis
Osteoarthritis, sometimes called degenerative arthritis or degenerative joint disease, is a condition that involves the breakdown of joint articular cartilage. Often the cause is unknown, but osteoarthritis may develop as a result of injury to the joint, excess body weight, or years of wear and tear on the joint articular cartilage. As joint cartilage wears away, the bone begins to make painful bone on bone contact. The early stages of osteoarthritis can be treated with a variety of conservative, non-surgical treatments. However, as the joint cartilage continues to wear away and the symptoms of osteoarthritis become more severe, surgery may be recommended to correct the damaged bone and cartilage.
SYMPTOMS
Osteoarthritis develops slowly over several years. The symptoms of osteoarthritis are mainly pain, swelling, and stiffening of the knee. The pain of osteoarthritis is usually worse after weight bearing activity. Early in the course of the disease, you may notice that your knee does fairly well while walking. Then after sitting for several minutes, the knee becomes stiff and painful. As the condition progresses, pain can interfere with even simple daily activities. In the late stages, the pain can be continuous and even affect sleep patterns.
DIAGNOSIS:
To diagnose osteoarthritis, a complete history and physical exam and a series of x-rays are taken. On an x-ray, a healthy knee joint has a space between the bones in the joint. Although you cannot see the cartilage on an x-ray, in the healthy knee, the cartilage is working to cushion and smooth the movement of the thighbone (femur) against the lower leg (tibia). On the x-ray of a knee with osteoarthritis, there is bone on bone contact because the articular cartilage between the femur and tibia has been worn away.
X-Ray of Healthy Knee
X-Ray of Knee with Osteoarthritis
Inflammatory or Rheumatoid Arthritis
Unlike osteoarthritis, inflammatory rheumatoid arthritis usually affects more than one joint at a time. The joints are affected by excess fluid and the synovial membranes. The synovial membrane is the lining of the joint. The normal function of the synovial membrane is to produce synovial fluid, which lubricates and nourishes joint cartilage. There are many types of inflammatory arthritis, the most common being rheumatoid arthritis. With rheumatoid arthritis, the synovial tissue actually attacks articular cartilage resulting in joint destruction. The symptoms of rheumatoid arthritis vary, but many people experience painful joint swelling and progressively limited joint movement as the cartilage wears away.
TREATMENT
Non-Operative Treatment
Osteoarthritis is a condition, which progresses slowly over a period of many years. Osteoarthritis cannot be cured. Treatment is directed at decreasing the symptoms, and slowing the progress of the condition. There are a number of non-surgical treatments for osteoarthritis. Moderate doctor-prescribed exercise and physical therapy are excellent ways to keep joints moving and to help relieve moderate joint pain. Joints that are not regularly exercised become tight and painful.
Excess body weight places extreme amounts of pressure on the joints. If you are overweight, weight loss may be recommended to help relieve unwanted stress and pain on your joints. Assistive devices, such as a cane or a walker, can help reduce the pressure placed on joints and alleviate some pain. Resting after activity can also help control moderate joint pain.
The treatment of osteoarthritis depends on how far advanced the condition is. In the early stages, treatment for osteoarthritis is usually directed at decreasing the inflammation in the joint. Anti-inflammatory medications, such as aspirin and ibuprofen, are useful in decreasing the pain and swelling from the inflammation. Sometimes a series of injections with a joint like fluid, a process called viscosupplementation, will be beneficial. If the symptoms continue, a cortisone injection may be used to bring the inflammation under better control and ease your pain. Cortisone is a very powerful anti-inflammatory medication, but does have secondary effects that limit its usefulness in the treatment of osteoarthritis. The major drawback in the use of intra-articular injections of cortisone is the fact that it may actually speed the process of degeneration when used repeatedly. We use cortisone sparingly, and avoid multiple injections.
There are also braces that can reduce the pressure on the side of the knee that is most involved. These braces have been designed mainly for the more common condition of early wear and tear in the medial compartment for the knee.
Finally, shoe inserts may be prescribed to unload the arthritic knee.
Arthroscopy
Arthroscopy may be useful in the treatment of osteoarthritis of the knee. Arthroscopy allows the surgeon to debride the knee joint. Debridement consists of; cleaning out the joint of all debris and loose fragments and thoroughly irrigate the knee. During the debridement, any loose fragments of cartilage are removed, and the knee is washed with a saline solution. Debridement of the knee using the arthroscope can sometimes afford temporary relief of symptoms.
Proximal Tibial Osteotomy
Osteoarthritis affects the inside half (medial compartment) of the knee more often than the outside (lateral compartment). This can lead to the lower extremity becoming slightly bow-legged, or in medical terms, a genu varum deformity. The result is that the weight bearing line of the lower extremity moves more medially (towards the medial compartment of the knee). (It's really all in the physics/biomechanics of the situation.) The end result is that there is more pressure on the medial joint surfaces, which leads to more pain and faster degeneration.
In some cases, re-aligning the angles in the lower extremity can result in shifting the weight-bearing line to the lateral compartment of the knee. This, presumably, places the majority of the weight-bearing force into the healthier (lateral) compartment of the knee. The result is to reduce the pain and delay the progression of the degeneration of the medial compartment.
The procedure to realign the angles of the lower extremity is called a Proximal Tibial Osteotomy. In this procedure, a wedge of bone is removed from the lateral side of the upper tibia. This converts the extremity from being bow-legged to knock-kneed. This procedure is not always successful, and generally will reduce pain, but not eliminate it altogether. The advantage to this approach is that very active people still have their own knee joint, and once the bone heals there are no restrictions to activity level.
The Proximal Tibial Osteotomy in the best of circumstances is only a temporary solution. It is thought that this operation buys some time before ultimately needing to perform a total knee replacement. The operation usually lasts for 5-7 years if successful.
Total Knee Replacement
The ultimate solution for osteoarthritis of the knee is to replace the joint surfaces with an artificial knee joint. The decision to proceed with a total knee replacement is usually considered in people over the age of 60, (although younger patients sometimes require the surgery simply because no other acceptable solution is available to treat their condition). The main reason orthopaedic surgeons are reluctant to perform knee replacement on younger individuals, is that the younger the patient, the more likely the artificial joint will wear out. Replacing the knee the second and third time is much harder and less likely to succeed.
Artificial knee joints last about 10 years in an elderly population. Younger patients are more active and place more stress on the artificial joint that can lead to loosening and failure earlier. Obviously, younger patients are also more likely to outlive their artificial joint, and will almost surely require a revision at some point down the road.
The Knee Replacement Procedure
Total knee replacement (TKR), also called total knee arthroplasty, uses metal alloy and polyethylene (plastic) components to resurface the bones in the knee joint. The implants are designed to re-create the shape of the bones in a healthy joint.
The end of the thighbone (femur) can be compared to a rocking chair. It has two distinct surfaces, or rockers, that contact the top of the shinbone (tibia). Each rocker is called a condyle, and there are two condyles at the end of the thighbone. In a TKR, the femoral component re-creates each rocker at the end of the thighbone. The top of the tibia is covered with a metal tray that is used to support a polyethylene plastic bearing. The polyethylene acts as the joint's cartilage, absorbing stress and providing smooth movement. The Patellar articular surface may or may not be replaced. If replaced the polyethylene on the back of the kneecap also provides smooth movement against the femoral component.
Healthy Knee
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Arthritic Knee
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After Surgery
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Knee Implant
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