Of you all that have had a "total replacement" did they replace the knee cap as well?
That is a good question, and as far as I have seen, generally, unless there is a real need to replace the kneecap, or remove it, they keep the original. If you are contemplating the surgery, that would be a great question to ask of your surgeon. In fact anyone should make a list and fire away with questions so you are an informed consumer. You should also be clear with your orthopedic surgeon what your goals and expectations are to ensure you and the Doc are on the same page. One of the reasons that I always seek out sports medicine orthos is that they are accustomed to working with athletes who expect to recover from injury and get back at whatever they do. I try to avoid doctors who only work with geriatric patients (nursing home attitude doctors). I may be considered old, but I am
not nursing home material.
To answer the question you asked, no they did not replace the kneecap, but they did resurface the back side of it so that it would track with the other implanted parts. Basically the patella fits into a groove in the front at the lower end of the femur (thigh bone) just above the middle of the joint with the tibia (lower leg), and while it rides up and down in that groove, it helps keep the patellar tendon and the rest of the knee aligned. Often the back of the kneecap (patella), in keeping with the condition of the rest of the joint, is arthritic, rough, noisy, and correspondingly painful, so in some cases I have known of, they clean up the surfaces to smooth them off again even if artificial parts are not attached to it. When they replace the worn out bone ends, they change the shape/contour of that alignment groove, and the natural shape of the kneecap might not ride smoothly in that new channel, so it may need revision.
Different manufacturers use somewhat different designs, and knee replacement parts come in "kits" with specifically sized and angled parts. With the advances in technology, most of the people I know who have recently had total knee replacements have customized fits that mimic natural angles of joints in that person, and are sized to match the size of the skeleton that they will be fitted to.
Mine came with a custom "cutting block" that provided the surgeon a specific template with which to do his "carpentry". This cutting block was developed after a 3D CAT scan that allowed modeling of the bone ends involved and provided angle corrections for the longterm bow in the joint that had developed over 2 decades of deterioration. When done it was straightened back to what it had been like in my 20s, and matches my still good other knee. Which by the way improved things on my hip and back as well, an added benefit.