Acute patellar dislocation is a common injury that can lead to disabling knee pain and/or recurrent instability. Recent research focuses on patellofemoral anatomy, on the injuries associated with acute patellar dislocation, and the specific contributions the injured structures make to patellar stability in intact knees. The implication is that injury to specific structures may have important consequences in converting a previously asymptomatic, though perhaps abnormal, patellofemoral joint into one that is painful and/or unstable. These studies have been intended to improve the precision of surgical treatment for patellar instability, and their results are driving refinements in our surgical indications as well as technique.