I am also a member of the PGR! Nice to see a familiar sight...
Soon my knees will need replacement. the right is a standard replacement, really. The left, however, due to that damn MRSA, it will be different. Normal replacements rely on the existing ligaments, but since the bug ate mine up, I only have one of the four that is anything close to normal. I will lose mobility to gain stability. Click the gif below to see the front/back motion. It will also move to the inside quite nicely...