Understanding the Knee Joint Replacement Process

From an interview with
Dr. Rodney Alan
McLeod Orthopaedics Florence

Ever wonder what happens during knee joint replacement surgery? McLeod Orthopedic Surgeon Dr. Rodney Alan visually walks through the process step-by-step.

Here’s a summary of Dr. Alan’s description:
The most common conditions that lead to joint replacement are osteoarthritis, rheumatoid arthritis, posttraumatic arthritis and, in some cases, osteonecrosis. The most common, osteoarthritis, is associated with aging or wear and tear. Rheumatoid arthritis is usually associated with autoimmune problems, which leads to synovitis or inflammation of the joints and, ultimately, bone loss. Post-traumatic arthritis usually develops years after a major injury and is often preceded by other surgical procedures to try to repair that traumatic injury.
In the process of doing joint replacement surgery, we perform what’s called an arthrotomy, an incision around the joint capsule. We usually dislocate the kneecap. Most surgeons will resurface that back portion of the patella (kneecap), which means removing the worn-down cartilage and bone. Then, we prepare it so that you can cement or glue a plastic patellar component to the backside of the kneecap.
Following that, we will prepare the end of the femur (top bone of the knee) to accept a femoral (lower bone of the knee) component. This involves making several cuts — one at the end of the bone, one on the top of the bone, one on the bottom of the bone and two angled cuts in the middle of the bone. This enables the implant to be placed on the end of the bone and secured with cement.
The final preparation involves the upper part of the leg bone, or proximal tibia. It requires removal of one of the main cruciate ligaments and, in some cases, both the ACL and the PCL, the entire meniscus, and the cartilage and subchondral bone.
You have a tibial, a femoral and a patellar component. After we’ve resurfaced each of the components, the knee is stitched back together. 
Certain risk factors adversely impact the outcome on joint replacement. These risk factors include morbid obesity, uncontrolled diabetes and the need for chronic pain medicines. We know that someone on chronic opioids does not have a good outcome. We know that patients without controlled diabetes are going to have more complications than patients who have their diabetes controlled. And lastly, we know that the pain relief associated with joint replacement is going to be much better in someone who has an ideal body mass index compared to someone whose body mass index is greater than 40.

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