Sports Medicine Knee Arthritis

What is Knee Arthritis?
Arthritis is inflammation of the knee joint. It can occur in any of the three compartments of the knee, the medial, lateral, or patellofemoral. Arthritis leads to the loss of articular cartilage, which covers the ends of the bones, and allows the bones to move smoothly against each other. When the cartilage is damaged, the bones rub together during joint motion, and the patient is said to have ‘bone-on-bone’ in the joint. This can lead to pain with motion, or at rest, clicking or grinding with motion, and a loss of strength. When arthritis becomes severe, the body attempts to stabilize the joint and limit motion by forming bone spurs, or extra bone around the edges of a joint.

What causes Knee Arthritis?
There are two main types of arthritis: rheumatoid and osteoarthritis. Rheumatoid arthritis occurs when the body’s immune system causes the inflammation; osteoarthritis occurs when the joint wears out as a result of overuse, age, or injury. When an infection in the joint leads to loss of cartilage, it is called septic arthritis.

What are the symptoms?
People suffering from knee arthritis in the femorotibial joint will experience pain, stiffness and loss of strength. A ‘grinding’, ‘clicking’ or ‘locking’ sensation may be felt in the affected joint. Loss of motion can become severe, and the patient may have trouble performing tasks, such as walking long distances. Patients suffering from arthritis of the patellofemoral joint will often complain of ‘giving way’ or buckling of the knee. This can occur as the kneecap passes over bone spurs in the knee, giving the patient the sensation of instability. Patients with patellofemoral arthritis have trouble using stairs, squatting, or standing after prolonged sitting.

How is Knee Arthritis diagnosed?
Arthritis is diagnosed on physical exam and on x-ray. Your orthopaedic surgeon will examine your knee, noting range of motion, strength, clicking and pain with motion. Your surgeon will obtain x-rays, and sometimes a CAT scan or MRI to evaluate the arthritis.

How is it treated?

Knee arthritis can be treated with physical therapy, to strengthen the muscles that support the joint. The stronger the supporting muscle, the less the body will need to rely on bony architecture to stabilize the joint. This will lead to less stress across the arthritic area. Because arthritis is inflammation, your surgeon may prescribe anti-inflammatory medication or offer an injection to reduce the inflammation. For arthritis in its beginning stages, nutritional supplements are available to slow progression of the arthritis. An injection of the patient’s own blood, which is processed to enhance its healing properties, has shown promise for treating arthritic conditions.

When non-operative treatment has failed, your surgeon may suggest surgery. Three surgical options are available for knee arthritis. Arthroscopy of the knee, or a ‘knee scope’, involves placing a tiny camera in the joint to remove injured cartilage. Although not a cure, this procedure may provide long lasting relief in patients suffering mechanical symptoms, such as catching and locking. For more severe cases, a total, or partial knee replacement may be offered. This involves removing the joint and replacing the injured cartilage with a smooth metal or plastic implant. This allows the knee to move smoothly, reducing pain and, in many cases, improving motion. For patellofemoral arthritis, the surgeon has several options. Knee arthroscopy to remove the injured cartilage may be effective. If the arthritis is limited to the outside of the kneecap, releasing the ligament that holds the kneecap in place may improve the patient’s symptoms. For severe arthritis in young active patients, a procedure to elevate the kneecap and lift it out of the groove may be performed. Finally, for older patients, a replacement of the patellofemoral joint is available. If arthritis involves other compartments, a total knee replacement is the best option.

The normal knee contains smooth cartilage which covers the end of the femur and tibia, the bones which compose the knee. A knee becomes arthritic when there is damage to this smooth, or articular cartilage. As the damage progresses, the cartilage, and eventually the underlying bone, is worn away. Because cartilage and bone occupy space in the knee, the loss of these structures will cause the knee to change shape. That is why people with arthritic knees will often appear to be bow-legged or knock kneed when standing and putting weight on their knees

Osteochondritis Dissecans (OCD) of the Knee

What is OCD of the Knee?
Osteochondritis Dissecans is a condition in which fragments of bone and cartilage become separated from the joint surface and form loose bodies in the joint. These fragments usually originate from the femoral side of the joint.

What causes OCD?
It is currently thought that most OCD lesions occur as a result of a traumatic injury that occurred in the patient’s past. They can also occur in the athlete as a result of overuse. Some lesions do not have an identifiable cause.

What are the symptoms?
Patients will complain of clicking and locking in the knee. Patients complain of pain, and are often unable to fully flex and extend their knee.

How is an OCD lesion diagnosed?
Physical exam reveals loss of motion or clicking in the knee. The area the bone chips came from may be tender to the touch. X-rays will confirm the diagnosis. An MRI may be obtained to help determine stability of the fragment. Fluid seen behind the fragment on MRI is an indicator of instability, and an indication for surgery.

How is it treated?

Stable lesions, those not likely to displace, are treated with rest, anti-inflammatory medications and observation.

Unstable lesions, or those that have become loose bodies, are removed arthroscopically. Depending on the patient’s age and activity level, a microfracture may be performed at the time of arthroscopy. A microfracture is a procedure used to repair damaged cartilage. The surgeon drills into the bone where the lesion is located. The drill hole allows bone marrow to leak into the lesion bringing with it blood cells that are capable of forming new cartilage.