Knee replacements are performed more often than hip replacements in the US. There are several types of common knee replacements including bicondylar knee, unicondylar knee, and patellofemoral knee replacements.
Use this information to build a basic understanding of what is involved in knee replacement procedures.
Tibial inserts touch against the patient's femur. How much the patient is able to bend their knee or rotate their leg is often determined by the height of the “post” in the middle of the insert. The post fits into a “box” in the femur. A lower post is less constrained; the highest post is most constrained.
Tibial inserts are made of polyethylene, which may be cross-linked or treated with an anti-oxidant such as vitamin E to prolong longevity.
Patellas are often attached to the inside of the patient’s patella so that the polyethylene glides along the slope of the femoral component. Many physicians do not resurface the patient’s patella.
Robotic assistance is used to provide an exact cut to the femur and tibia during knee replacement. An inexact cut may lead to early revision.
Designed to provide increased stability for the tibia, their usage is about 10% of primary knees.
Over 80% of knee replacements are cemented systems. Generally two units of 40g of bone cement are used. Antibiotic bone cement may be used although physicians often concoct that themselves during the procedure. Extras include mixers and other devices to deliver the cement to the joint.
A mobile-bearing knee is designed to provide patients more flexibility by allowing them to pivot their foot and rotate their leg. A variety of knee designs accommodate this, but it generally involves a flat tibial base with an insert that can pivot along an axis.
Get the full Procedure Brief on Knee Replacement Procedures.