Knee replacement, or knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve the pain and disability of osteoarthritis. It may be performed for other knee diseases such as rheumatoid arthritis and psoriatic arthritis. In patients with severe deformity from advanced rheumatoid arthritis, trauma, or long standing osteoarthritis, the surgery may be more complicated and carry higher risk. Osteoporosis does not typically cause knee pain, deformity, or inflammation and is not a reason to perform knee replacement. Other major causes of debilitating pain include meniscus tears, cartilage defects, and ligament tears. Debilitating pain from osteoarthritis is much more common in the elderly.
Knee replacement surgery can be performed as a partial or a total knee replacement. In general, the surgery consists of replacing the diseased or damaged joint surfaces of the knee with metal and plastic components shaped to allow continued motion of the knee. The operation typically involves substantial postoperative pain, and includes vigorous physical rehabilitation. The recovery period may be 6 weeks or longer. Approximately 17% of patients who receive a total joint replacement need early replacement surgery which is a procedure which can cause serious complications for elderly patients. In order to help minimize the need for these operations a new coating for implants have been developed that could help them better adhere to the patient’s bone, preventing premature failure.
This would allow the implant to last much longer, to its natural lifetime, with lower risk of failure or infection. At present, artificial hips and knees are secured using bone cement, a polymer that resembles glass when hardened. However, in some patients, this cement cracks, causing the implant to detach from the bone. As a result the patient experiences loss of mobility and chronic pain. The new coating consists of a very thin film that is between 100 nanometers to one micron thick. It is made up from layers of materials that help to encourage a rapid growth of bone, such as hydroxyapatite, a natural component of bone that is made from calcium and phosphate. This material attracts mesenchymal stem cells from the bone marrow and provides an interface for the formation of new bone, whilst the other layer releases a growth factor, which encourages mesenchymal stem cells to transform into bone-producing cells called osteoblasts. After forming, the osteoblasts generate new bone to fill in the spaces surrounding the implant, securing it to the existing bone. In addition, the coating could be used in dental implants.