Partial Knee Replacement Surgery
A partial knee replacement is when only one or two compartments of a natural knee are resurfaced, rather than the entire articular surface of the knee. We describe the knee as having three compartments. The innermost part of the joint is called the medial compartment. Frequently, this is the compartment that develops symptomatic osteoarthritis first and can lead to the leg appearing “bowlegged”. We call this genu varus. Less frequently, the outermost part of the knee joint or lateral compartment initiates the arthritic process. This can be painful and some people may complain that their leg is becoming “knock kneed”. This condition is referred to as genu valgus. Finally, the articulation between the knee cap and femur can become arthritic and painful. Often this patella femoral joint will wear out secondary to the arthritic process which first starts in one of the other two compartments. Imagine how the tracking of the patella becomes compromised as the alignment of the leg / knee is altered. Eventually, all three compartments become involved in the arthritic process.
A partial knee replacement attempts to interrupt this by only treating the involved compartment(s). Many patients experience a much faster recovery because so much less dissection is done and the uninvolved compartments and structures are not violated. Many patients also report that the partial knee replacement feels “more natural”. Some patients also report better proprioception, which refers to our brain knowing where our body is in space. This may be because there is less interruption to normal neurologic pathways by preserving the cruciate ligaments and the uninvolved compartment.
The historic track record of partial knee replacement has been less consistent than with the total knee. It is a surgery that is even less forgiving than the total knee. Optimizing component balance and tracking is critical. In my experience, it is an elegant and wonderfully effective way to treat certain conditions.
Critical is that the indications to perform the surgery are appropriate and the technique is optimized. It has the potential of stopping the arthritic progression to end stage disease. In my experience, using the MAKO robotic-assisted technique has vastly improved the accuracy and reproducibility of my performing these procedures. Visit the Video Gallery to see a Video of the MAKO robotic-assisted technique.