Diagnosis

Diagnosis
Symptoms of arthritis often start out mild and typically worsen as time progresses. Common symptoms include pain, stiffness and swelling. Pain is usually associated with activity, but as arthritis progressively worsens, pain can occur at rest without activity or even wake you up at night. Stiffness is a common complaint, usually coinciding with swelling in the joint. When a joint is irritated, the lining of the joint creates extra joint fluid just as your eye produces tears if you get something in it. However, unlike in the eye where tears can exit, the fluid in a joint builds up and causes pain and decreased motion. When joints become severely arthritic, the once smooth shiny cartilage surface becomes rough and pitted, like an old road with potholes and cracks. Grinding can be felt or even heard with movement of the joint (Figure 6). Arthritic symptoms typically wax and wane. As the arthritis worsens, the episodes of pain become more frequent and more severe. Initially, arthritis symptoms are more of a nuisance, but with severe end-stage arthritis, the symptoms can affect your daily activities, your work and your quality of life.

Physicians make a diagnosis of osteoarthritis based on symptoms the patient presents with and physical examination findings. Imaging tests are used to confirm the diagnosis. X-rays may show bones that are deformed or too close together due to a decrease in the amount of cartilage between them. Most people over 60 years old have changes associated with the disease on x-ray, but about one-third have actual symptoms. 

The “history” is the story of your knee pain. The doctor will inquire how long you have had pain, its severity, how this affects you ability to function and perform daily activities, previous treatments and your past medical history. Feel free to express how your knee pain affects your quality of life and what your expectations are after treatment. These are all important pieces of information that your doctor needs to know in order to understand your perspective on your knee pain.

Most patients with knee osteoarthritis are middle-aged or elderly. They have pain and stiffness in the knee area leading to a decrease in function, such as difficulty with walking or bending. Morning stiffness is common but usually does not last for more than 30 minutes. Pain is worsened by activity and improved with rest. Many patients complain of increased symptoms during damp, cold weather. The reason for this is unclear, but it may have to do with changes in pressure inside the knee and in the environment.

The doctor will then perform a physical examination of your knee. It is important for your doctor to see how you walk, the alignment of your legs, how your knee bends and straightens, where your knee hurts, if there is any swelling, if your ligaments are stable and if the muscles, nerves and blood vessels in your legs all work well. The physical exam allows the doctor to make a diagnosis and to determine the treatment options most appropriate for your knee.

Imaging studies are an important part of your visit with the doctor. X-rays allow the doctor to see the alignment of the knee, the degree of cartilage wear, presence of bone spurs and if there is anything unusual with the bony anatomy (Figure 9). When an x-ray beam passes through the hip, the bones catch the beams and appear bright on the x-ray. The beams pass right though the soft tissues and cartilage, however, so these do not show up. Magnetic resonance imaging (MRI) tests are sometimes performed to assess the soft tissue structures, ligaments and cartilage of the knee. The MRI is a good test to look for meniscal tears, ligament injuries and to look at the articular cartilage. This is particularly useful if the plain (regular) x-rays do not show any significant arthritic changes.

In 1986, a study was published describing a set of criteria for classification of knee osteoarthritis. The criteria consisted of symptom presentation (history), physical examination and laboratory findings. History findings consistent with osteoarthritis included age greater than 50 years old, morning stiffness lasting less than 30 minutes and crepitus or creaking in the joint. Physical findings included bony tenderness or enlargement combined with lack of warmth of the skin overlying the knee (increased joint temperature could be a sign of infection). Laboratory tests that may be performed include: Erythrocyte Sedimentation Rate (ESR), Rheumatoid Factor (RF) and Synovial fluid (the liquid that acts as a lubricant in joints and provides nutrition for the cells in the cartilage) analysis. The tests should not reveal any signs of infection. X-rays may reveal osteophytes or bony overgrowths.