Overview

Arthritis is a condition that affects the joints, leading to pain and dysfunction. The joints in our bodies are located where the ends of our bones meet to allow movement and function. Many different kinds of joints allow different types of movement. Some behave like a hinge, like the knee joint (Figure 1a and 1b), while others move like a ball and socket, such as the hip joint (Figure 2a and 2b). The ends of the bones are lined with a smooth, glistening surface called “articular cartilage” (Figure 3). If you have seen the end of a chicken bone, the white, shiny surface there is the articular cartilage. This cartilage allows the bones to move smoothly relative to each other and also provides a cushion. When articular cartilage becomes injured or damaged, the result is arthritis (Figure 4, 5a and 5b).

According to the Center for Disease Control, arthritis is a common condition that affects one in five adults. In the year 2006, an estimated 46 million Americans were diagnosed with arthritis. This condition is the most common cause for disability in the United States.

Arthritis can be caused by a number of conditions, but the three most common causes are osteoarthritis, rheumatoid arthritis and post-traumatic arthritis. Osteoarthritis is the most common type, also known as “wear and tear” arthritis. Over time, the cartilage progressively degenerates and results in joint pain and stiffness. Rheumatoid arthritis is an autoimmune disorder affecting the synovium, or joint lining, which results in destruction of the articular cartilage and pain. Post-traumatic arthritis is the result of an injury to the joint (fracture or ligament tear), which results in direct damage to the cartilage and can lead to accelerated wearing away of the joint surfaces.

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.

Initial treatment usually begins with simple, non-operative treatment (treatment without surgery). The goals of non-operative treatments are to help you deal with the pain and to prevent further joint destruction. One means of addressing pain is with over-the-counter medications such as anti-inflammatory medications (i.e., ibuprofen or naproxen) or pain medications (i.e., acetaminophen). Various types of injections are also available (i.e., cortisone or hyaluronic acid injections) to help reduce pain (Figure 7). Changing your lifestyle to avoid activities that would cause further cartilage destruction is helpful in minimizing exacerbation of the joint pain. Walking aids such as a cane or walker are helpful in unloading some of the forces going across a painful, arthritic joint. When non-operative treatment fails, surgical options are considered.

The knee joint is made up of four bones:  the femur (thigh bone), the tibia (the larger shin bone), the fibula (the smaller shin bone) and the patella (knee cap) (Figure 8). Articular cartilage, the shiny, glistening surface on the ends of the bones, allows the joint to move and glide. The ligaments on either side of the knee are called collateral ligaments, and two criss-cross ligaments in the center of the knee are called the cruciate ligaments. These ligaments provide stability for the knee. Between the femur and the tibia are two C-shaped cartilage rings, each one called a meniscus. The meniscus serves as a shock absorber and also provides some stability to the knee. The lining of the joint, called the synovium, serves to produce lubricating joint fluid.