Symptomatic knee osteoarthritis begins with pain. Pain will be present with certain activities such as running, climbing stairs, and walking. Pain at night, joint swelling, knee stiffness, and locking/catching are other symptoms of knee osteoarthritis.
During osteoarthritis the articular cartilage degenerates, the lining of the joint (synovium) becomes inflamed, and the subchondral bone remodels and forms osteophytes and bone cysts. Some of the known factors that play a role in this are proteolytic enzymes. Matrix metalloproteases (MMPs) are responsible for breaking down cartilage. Tissue inhibitors of MMPS (TIMPs) play a role by inhibiting these enzymes. When there is an imbalance of MMPs and TIMPs the degenerative arthritis process proceeds. Inflammatory cytokines, like IL-1, IL-6, and TNF-alpha, also play a role by increasing creation of MMPs.
The diagnosis is often made by careful questioning and physical exam by a healthcare practitioner then confirmed with imaging including x-rays and possibly MRI. On X-rays we can see joint space narrowing, osteophytes, and subchondral bone cysts and sclerosis. The MRI will show detailed degenerative changes in the cartilage and bone.
Conservative management for knee osteoarthritis includes ice/heat, non-steroidal anti-inflammatories (ibuprofen or naproxen), bracing, weight loss, and physical therapy. Often when conservative treatment fails, physicians will often move on to corticosteroid injections which can help decrease pain and improve function temporarily. When symptoms and severity of arthritis become severe enough physicians will often refer to orthopedic surgery for possible joint replacement. Corticosteroid injection combined with anesthetics can be toxic to chondrocytes, the cells that produce cartilage, and joint replacement comes with the risk of a major surgical procedure. According to the American Academy of Orthopedic Surgery (AAOS), complication rate is around 5% and the chance of dying within 30 days of surgery is 1 out of 400.
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