A patella fracture is usually a split with your kneecap, the bone that handles your knee joint. It’s usually a result of a traumatic injury, like a slide or simply a blow for your kneecap. The American Academy of Orthopaedic Surgeons (AAOS) describes the patella can split in other ways, https://www.theorthopaedicandpainpractice.com/what-are-patella-fractures/