Patellofemoral dislocation is when the patella jumps completely out of the walls of the groove in the femur bone, making the joint look horribly deformed.

The joint usually dislocates to the lateral side, often tearing the medial patellofemoral ligamen (MPFL) on the medial side.
Reduction of patellofemoral dislocation
The dislocation may reduce spontaneously at the time, or it may need to be reduced under sedation or anaesthesia.
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FORUM DISCUSSIONS
Patella dislocation 2 weeks into recovery.
A dislocated knee and very vague answers given to me by hospital....please help!
CLINICAL PUBLICATIONS
Cartilage lesions in patellofemoral dislocations: Incidents/locations/when to treat. Farr J, Covell J and Lattermann C. Sports Med Arthrosc. 2012 Sep; 20(3): 181–186.
Medial patellofemoral ligament reconstruction: patient selection and perspectives. Baer MR and Macalena JA. Orthop Res Rev. 2017; 9: 83–91.