This is a major complication which occurs very rarely. Every precaution is taken to prevent it. Fat legs are more prone to this complication. The odds of this occurring are probaby one in many hundreds. If it does occur, the affected nerve usually recovers after 6 to 12 months.
Sensation usually returns to normal within a few months.
Patellar complications can occur. The plastic part on the patella can wear through. These problems sometimes need reoperation for correction. Injuries to the arteries of the leg is a remotely possible but serious complication. The major arteries of the leg lie just behind the knee joint.