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To understand exactly what I do from a medical standpoint is to understand basic anatomy. The hip anatomy is a ball and socket joint. The acetabulum which is the socket part of the joint articulates with the femoral head which is the ball part of the joint. During surgery, we replace this joint with metal and plastic.
The acetabulum which is cup part of the bone is replaced with a metal shell which is grooved and porous. That is then lined with a plastic liner. We’re using plastic liners most commonly now since other types of liners – ceramic and metal – have been called into question.
The femoral head is then removed and replaced with what's called a prosthetic head which is either made out of metal - cobalt chrome typically - or ceramic. This is basically the same type of ceramic that they use on a space shuttle and it's very strong and durable. There is also a femoral stem that sits inside of the femur which allows the bone to grow onto the femoral stem. This all incorporates into the hip joint to allow you to get back to normal functional life.
The knee joint is actually a much more complex joint than the hip. The hip is really a ball and socket joint. The knee joint is really more than just a simple hinge. It also allows for swinging and sliding of the femur on the tibia. There are three major knee bones: the femur, which is the thigh bone, the chin bone which is the tibia, and the patella which is the kneecap. There are two shock absorbers in the knee joint which are called the medial meniscus and the lateral meniscus.
The medial meniscus is on the inside portion of your knee joint and the lateral meniscus is on the outside portion. There are four major ligaments that we need to know about: the anterior cruciate ligament - the ACL, the posterior cruciate ligament - the PCL, the medial collateral ligament - the MCL, and the lateral collateral ligament – the LCL. These ligaments are on the sides of the joint. The reason we care about these ligaments so much is that as the arthritis process advances, not only does the cartilage wear out but the knee joint becomes scarred and require additional treatments to improve both stability and function of the knee joint.
What we're replacing and re-servicing in the joint is the femur which is replaced with metal. The tibia is replaced with a metal plate as well. And then there's a plastic insert, a plastic liner, that sits between them that allows you to function or have a relatively normal knee joint. The menisci are removed every time. There's just no room for the menisci within this artificial knee joint. We also remove the diseased cartilage.
The ACL is also typically removed every time. With the PCL, sometimes we can preserve it, and sometimes we can't, depending on how severe the arthritis is. The LCL and the MCL are preserved every time.