The contiguous surfaces of the bones present flat, oval facets covered with cartilage and connected together by an articular capsule and by anterior and posterior cruciate ligaments.

If the dislocation is recognized and treated properly, prognosis is typically good, although injury to the common peroneal nerve may occur.

Inferior dislocations are exceptional as they usually only occur in avulsion (traumatic amputation) injuries.

Subluxation may also occur in diseases with ligamentous laxity (e.g., Ehlers-Danlos Syndrome), muscle weakness (e.g., muscular dystrophy), or secondarily to degeneration (e.g., in rheumatoid arthritis).

[2] This article incorporates text in the public domain from page 348 of the 20th edition of Gray's Anatomy (1918)