Arthritis of the Knee - Overview
An interview with Dr. Richard S. Laskin and Dr. Russell E. Windsor
Attending Orthopaedic Surgeon, Hospital for Special Surgery
Professor of Surgery (Orthopaedics), Weill Medical College of Cornell University
Richard S. Laskin, MD
Chief of the Division of Arthroplasty
Attending Orthopedic Surgeon
Hospital for Special Surgery
Overview
Each year, thousands of people with arthritis of the knee seek treatment at the Hospital for Special Surgery (HSS). This common condition can arise from a number of causes, including osteoarthritis (the most widely diagnosed form of arthritis), inflammatory disease such as rheumatoid arthritis, and arthritis that develops after a trauma or injury.
Regardless of the underlying condition, patients with arthritis of the knee share in common a loss of the cartilage that lines the ends of the leg bones that make up the knee joint. Eventually, in an inevitable progression, bone rubs against bone. The patient experiences this process as stiffness, pain, and disability.
Standing anteroposterior radiograph of a normal knee. Note that the lateral joint space is slightly wider than the medial joint space.
Osteoarthritis of the knee. Note that the medial joint space is significantly narrowed and osteophytes (bone spurs) have formed along the margins of the joint.
At one time, arthritis of the knee resulting from osteoarthritis and post-traumatic arthritis was seen more commonly in men. The latter diagnosis was seen in men who had experienced an injury such as a torn anterior cruciate ligament or a torn meniscus, and who, even with appropriate treatment, eventually developed arthritis in the joint.
Today, with greater participation by women in a range of recreational and sports activities, that trend has changed and arthritis of the knee arising from these conditions is seen about equally among the sexes. Arthritis of the knee that is associated with rheumatoid arthritis is seen more commonly in women.
Gender can also play a role in the specific area of the knee in which the arthritis develops, with women—because of their wider pelvic structure—being more likely to develop erosion on the "outer" portion of the knee, resulting in a valgus deformity. This is manifest as a knock-kneed stance. People with arthritis of the inside portion of the knee develop a varus deformity and tend to have a bow-legged stance. Some evidence suggests that genetics may also determine the type of arthritis that develops. In Japan, for example, arthritis of the knee is almost exclusively varus.
Treatments
Fortunately, a range of non-surgical and surgical options are available to treat all patients with arthritis of the knee.
Non-surgical
Non-surgical treatment includes the use of NSAIDs (non-steroidal anti-inflammatory drugs) such as ibuprofen and naprosyn, as well as a newer class of agents called the Cox-2 inhibitors for reduction of inflammation and pain relief. Injection with steroids can offer temporary, symptomatic relief, but are not generally recommended for prolonged use.
Visco-supplementation involves injection of a viscous substance that resembles the synovial fluid normally found in the joints. This therapy also offers temporary relief of symptoms in some patients, but repeated injections are required. Some patients also report relief of symptoms after taking glucosamine and chondroitin supplements, however there is not a good body of scientific evidence to establish their efficacy, and the FDA does not regulate their use.
In addition to these treatments, patients are often advised to modify their activities, and when appropriate, to lose weight to reduce stress on the joint. Physical therapy can offer considerable relief as well. As the patient strengthens the muscles that surround and support the knee, the stress on the joint is reduced, as is associated pain. Use of a cane or unloader braces (which literally reduce the stress load on the joint) may also help some patients.
Surgical
Surgical treatment options for arthritis of the knee include osteotomy (in which the bone is cut to realign the joint) and, more frequently, total knee arthroplasty (TKA, also known as total knee replacement or replacement of the joint). Depending on the extent of the arthritis, some patients may be eligible for a unicompartmental surgery in which only one part of the joint is replaced. In addition, for patients with arthritis in both knees, TKA in both joints—in a single procedure—is an option.
People of all ages, including those in their 80s and 90s, may elect to have TKA, and excellent results are common. Most prosthetic joints last for 20 years or more. The availability of precise surgical techniques and durable materials to replace the arthritic knee joint has made TKA a more attractive option for many individuals.
Overall, TKA is considered highly safe and effective. The surgery is performed with epidural anesthesia—the same type of anesthesia that many women receive during childbirth—so that they may be awake throughout if they so choose. This form of anesthesia significantly reduces the chance of complications associated with surgery and allows a more rapid recovery. Patients are usually hospitalized for no longer than 5 days.
Key to the success of these procedures is surgical technique and the selection of the appropriate prosthesis. Orthopaedic surgeons determine the latter based on the patient’s age and lifestyle. In addition to relieving pain and disability, the goal of TKA is to restore range of motion, which is measured in degrees. Generally, a reasonable expectation is to regain the same range of motion the patient had prior to surgery, with the high end of the range being about 120 degrees. However, some orthopaedic surgeons are now using a newer prosthesis that can allow for bending between 135-140 degrees.
Rehabilitation
Patient adherence to a well-designed rehabilitation program also plays an important role in determining outcome. At HSS, many individuals find the use of continuous passive motion (CPM) machines—equipment that moves the patient’s knee through a range of motion—to be particularly helpful.
posted 10/15/2002
Diagnostic imaging examinations provided by HSS Radiologists -- Summary prepared by Nancy Novick
