Arthritis is inflammation of a joint. The knee can be divided into three compartments: medial (inside), lateral (outside) and patellofemoral (front). Arthritis can be present in one, two or three compartments. Over time, the loss of the smooth covering on the ends of bones (aka - articular cartilage) causes pain and stiffness. This can lead to pain with motion or at rest, swelling, clicking or grinding and a loss of strength. When the cartilage is damaged or decreased, the bones rub together during joint motion, resulting in “bone-on-bone” arthritis. When arthritis becomes severe, inflammation occurs around the joint and extra bone is formed in an attempt to protect the joint, resulting in limited motion and strength.
The primary cause of arthritis is osteoarthritis (aka – “wear and tear” arthritis). Trauma and other illnesses like rheumatoid arthritis, systemic lupus, septic arthritis and psoriasis can result in degeneration of a joint, leading to symptoms of pain and lack of motion.
Arthritis of the knee causes pain, swelling, stiffness and loss of strength. Pain can be isolated to the medial, lateral or patellofemoral aspects of the joint or be generalized discomfort around the knee. Pain and swelling in the back of the knee may be from a Baker’s Cyst, an area of fluid collection that is caused by arthritis. A 'grinding', 'clicking' or 'locking' sensation may be felt. 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. Patients with patellofemoral arthritis have trouble using stairs, squatting, or standing after prolonged sitting.
Your surgeon will perform a thorough history and physical exam, which typically includes X-rays. Your surgeon will evaluate the range of motion, stability of the ligament and strength of the muscles surrounding the knee. X-rays may demonstrate decreasing space between the bones (joint space narrowing) and bone spurs (osteophytes) in areas of arthritis. MRI may be helpful to determine if other areas of joint cartilage or the meniscus has damage.
Knee arthritis can be treated with physical therapy, to strengthen the muscles that support the joint. The stronger the supporting muscles, 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. Your surgeon may prescribe anti-inflammatory medication or offer an injection to reduce the inflammation. Certain nutritional supplements may be beneficial to decrease pain and inflammation.
When non-operative treatment does not relieve symptoms, your surgeon may suggest surgery. Three surgical options are available for knee arthritis.
Minimally-invasive arthroscopy of the knee, or a 'knee scope', may be beneficial to “clean-out” the knee. Although not a cure, this procedure may provide relief in patients suffering mechanical symptoms, such as catching and locking. The entire knee joint, including joint cartilage, meniscus and ligaments can be evaluated during arthroscopy.
The definitive treatment for knee arthritis is joint replacement surgery. Your surgeon will resurface the ends of the bone where the cartilage has worn away, with metal and plastic implants. If the arthritis is localized to a single or two compartments (medial, lateral or patellofemoral), your surgeon will replace only the areas that are affected (unicompartmental or patellofemoral replacement). If the arthritis is present in all three compartments, a total knee replacement is required to alleviate symptoms. Reference “A Patient’s Guide to Partial Knee Resurfacing” or “A Patient's Guide to Total Knee Arthroplasty” for in-depth details about these surgeries.
Osteochondritis Dissecans (OCD) is a condition in which fragments of joint cartilage become separated from the bone. These fragments may peel from the bone and remain intact or completely separate from the bone, forming loose bodies that float in the joint. These fragments usually originate from the femoral (thigh bone) side of the joint but can originate from any compartment.
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.
OCD causes pain at a specific area in the knee. Patients will complain of clicking and locking in the knee, particularly if the fragment has separated and is floating around the joint. Patients are often unable to fully flex and extend their knee.
Your surgeon will perform a thorough history and physical exam, which typically includes X-rays. Your surgeon will evaluate the range of motion. The origin of the fragment may be tender to the touch. X-rays may or may not identify OCD. MRI is standard for OCD diagnosis. Fluid seen behind the fragment on MRI is an indicator of OCD.
Stable OCD lesions, those not likely to displace, are treated with anti-inflammatory medication, cryotherapy, activity modification and observation.
Unstable OCD lesions are evaluated by a minimally-invasive arthroscopic procedure. Sometimes the fragment can be repaired with small screws/tacks if it is still attached to the bone. If the fragment has separated from the bone and cannot be repaired, it will be removed and a cartilage regeneration or replacement procedure may be performed in the lesion. A microfracture procedure can be performed in the lesion to allow blood to soak the lesion. A cartilage graft, typically from a donor, can then be placed at the site. Over time, new cartilage will be formed over the lesion. Alternatively, your surgeon may choose to take a piece of cartilage from one area of the knee where it is not necessary and place it into the defect (autograft cartilage transplant procedure) .