Knee Arthritis
Knee Anatomy
The healthy knee is a hinge joint. The three bones that form the knee are the thighbone (femur), shinbone (tibia), and kneecap (patella). The femur and tibia are held together by ligaments, which are strong bands of tissue that stabilize the joint. The end of the femur, the top of the tibia, and the back of the patella are covered with a tough lubricating tissue called cartilage. Cartilage acts like a natural shock absorber, preventing both bone on bone contact and providing a smooth, pain-free surface for the bones to glide against. The knee also contains synovial membranes, which produce synovial fluid to help lubricate and nourish the cartilage.
Knee cartilage can be compared to the tread of an automobile tire, very durable but susceptible to wear over time. Osteoarthritis is a degenerative process, which results in the wearing out of the cartilage that protects the bones in the joints. As we age, the tread surface slowly erodes until the underlying bone is exposed. This exposed bone can be painful when the joint moves and bears weight.
Arthritis is a term that is used to describe over 100 different kinds of conditions that can affect the human body. Arthritis affects millions of Americans each year with symptoms including pain, stiffness, swelling, and loss of motion in affected joints.
Knee Replacement Procedure
Total knee replacement, also called total knee arthroplasty, uses metal alloy and polyethylene (plastic) components to resurface the bones in the joint. The implants are designed to re-create the shape of the bones in a healthy joint.
The end of the thighbone can be compared to a rocking chair. It has two distinct surfaces, or rockers, that contact the top of the shinbone. Each rocker is called a condyle, and there are two condyles at the end of the thighbone. The femoral component re-creates each rocker at the end of the thighbone. The top of the tibia is covered with a metal tray that is used to support the polyethylene plastic bearing. The polyethylene acts as the joint's natural cartilage, absorbing stress and providing smooth movement. The polyethylene on the back of the kneecap also provides smooth movement against the femoral component.
Partial Knee Replacement
In patients with only limited knee arthritis, surgeons may elect to perform a unicompartmental (partial) knee replacement. Unlike total knee replacement involving removal of all the knee joint surfaces, a unicompartmental knee replacement replaces only one side of the knee joint. Knee osteoarthritis usually occurs first in the medial (inside) compartment as this side of the knee bears most of the weight. In knees that are otherwise healthy, a unicompartmental approach allows the outer compartment and all ligaments to remain intact. By retaining all of the undamaged parts, the joint may bend better and function more naturally.
The Repicci II® - The First Minimally Invasive Knee Replacement Procedure Developed in conjunction with John Repicci, MD, the Repicci II® is a partial knee replacement designed to remove as little bone from the knee as possible. The entire surgery is performed through a very small incision, with minimal trauma to surrounding soft tissue. As a result, Dr. Repicci has reported that many patients leave the hospital on the day of, or the day after surgery, and are back to work within two weeks. The Repicci approach has demonstrated excellent results, with a 96% success rate after 5-8 years.
The Oxford® Unicompartmental Knee System - Leading surgeons in Oxford, England along with engineers at Biomet, developed the Oxford® Unicompartmental Knee System. It's the only FDA-approved, free-floating meniscal partial knee system available in the United States and has been utilized throughout Europe for more than two decades.
In a healthy knee, the meniscus serves as a shock absorber between the ends of the bones. The Oxford is the first partial implant with an artificial meniscal bearing designed to glide freely throughout the knee's range of motion, more closely replicating normal movement. The free-floating nature of the device also improves durability of the implant.
Published long-term clinical results on the Oxford® Knee demonstrated a 98% success rate at 10 years, equaling the results of the most successful total knee replacements. Studies also show most patients experience a rapid recovery and more natural joint function.
Not all patients are candidates for partial knee replacement. You should discuss your condition and treatment options with your surgeon.