The knee is the largest and most complex joint in the human body. It is also one of the most important joints, playing an essential role in carrying the weight of the body in a given direction. It is formed by the lower part of the femur, the tibial plateau and the knee cap, and enables hinge and rotating movements as the connection between the upper and lower leg.
When the knee joint is damaged, people can experience pain, swelling and decreased range of motion. This can make it difficult to perform daily tasks like standing, climbing stairs or walking. If the knee doesn’t respond to activity modification, anti-inflammatory medications and injections, knee replacement surgery may be a viable option. Your doctor may recommend knee replacement surgery if you have severe knee pain and disability from rheumatoid arthritis, osteoarthritis, or traumatic injury, and will make a determination based on the damage to your knee, bone strength, age, lifestyle and other medical conditions you have.
There are two types of replacement surgeries: total knee replacement and partial knee replacement, with total knee replacement surgeries comprising more than 90 percent of today’s procedures. During both surgeries an orthopedic surgeon will replace the damaged knee with an artificial device (implant). Although replacing the total knee joint is the most common procedure, some people can benefit from just a partial knee replacement.
Partial Knee Replacement
The knee is made up of three areas or compartments: medial and lateral (the sides of your knee) and patella-femoral (the knee cap). When fewer than three of these areas need to be replaced, it is called a unicompartmental or partial knee replacement.
Partial knee replacement isn’t suitable for everyone because you need to have strong, healthy ligaments within your knee. However, if only one side of your knee is affected, then partial replacement may be a possibility. Partial knee replacements can often be carried out through a smaller cut (incision) than a total knee replacement, and are typically less complicated than total knee replacements. This almost always means a quicker recovery and better function while giving the same level of pain relief as a total knee replacement.
Total Knee Replacement
Most total knee replacement surgeries resurface the bones at the top of your shin bone (tibia) and the bottom of your thigh bone (femur) with an implant made of metal and plastic parts. The end of the femur and top of the tibia are resurfaced and capped with a metal implants. There is a plastic or polyethelene spacer between the two metal components so the articulating surface is metal on plastic. A total knee replacement may also involve replacing the surface of your knee cap (patella) with polyethelene, although many surgeons prefer to leave it in its natural state because it will be less likely to fracture. When fit together, the attached artificial parts form the joint, relying on the surrounding muscles and ligaments for support and function.
After Knee Replacement Surgery
The average hospital stay after knee joint replacement is usually two to four days, and the vast majority of people who undergo knee joint replacement surgery have dramatic improvement in pain and range of motion. Once muscle strength is restored with physical therapy, people who have had knee joint replacement surgery can enjoy most activities although running for exercise not recommended. . The duration of physical therapy can vary, but typically outpatient therapy lasts from one to two months.
About Dr. Reimer
Dr. Nickolas Reimer is an assistant professor of Orthopaedic Surgery at Emory University. He specializes in the treatment of musculoskeletal tumors, total hip and total knee replacements and revision surgeries.