This is the TMINI Miniature Robotic Surgical System: a wireless robotic handpiece that assists surgeons in performing total knee replacement. It can “automatically compensates for surgeon hand movement to locate bone pins along precisely defined planes. Cutting guides are then connected to the bone pins for accurate bone resection.”
This robot can replace many instruments used for knee replacement surgeries. It has recently gained 510(k) clearance from the U.S. Food and Drug Administration (FDA). You can find out more here.