Some people with free patellar ligaments as well as the Formerly stated anatomical abnormalities resulting in extreme “maltracking” in the patella can put up with episodes of full “derailment” (dislocation) with the patella. Some surgeons are working with minimally invasive techniques making use of specially designed surgical devices and telescopes http://knee cap replacement https://www.theorthopaedicandpainpractice.com/knee-cap-replacement-understanding-the-basics-of-this-orthopaedic-surgery/