Standard Knee Replacement
The first knee replacement was done in 1968. The instrumentation was very crude and getting the implants to sit in just the right spot was very difficult. Over the years the instruments have improved markedly and the operation is much more reproducible now. Traditional knee replacement is one of the best operations done today. It is fantastic at relieving pain and restoring quality of life to people with bad knee arthritis. Unfortunately if the implants are not inserted correctly the plastic liner wears out and further surgery is needed.
Techniques were developed that allowed alignment (orientation) of the knee to be accurately measured. Unfortunately the only way we were able to achieve this goal was to put a rod up the centre of the femur (thigh bone) into the marrow cavity. This gave us very accurate alignment but was not fantastic for rotation. It also created a release of fat from the bone into the blood which traveled up into the lungs (and occasionally the brain). The release of fat into the blood is called a fat embolism and it interferes with oxygen transfer in the lungs. This makes recovery from the knee replacement surgery slower and sometimes causes difficulty breathing for many weeks.
The tibia or shin bone component is easier to insert correctly and both intramedullary (in the marrow cavity) and extramedullary (outside the bone) methods are available.
While this method has worked very well for many years we have worked hard to find a technique that does not require a rod to go up the bone and therefore does not cause damage to the lungs. We now have computer based knee replacement technology which allows us to insert the prosthesis very accurately with less blood loss and no fat traveling to the lungs.
I use patient matched technology rather than the older methods whenever possible when performing a primary total knee replacement.