Missed Transient Patellar Dislocation in Younger Patients With Traumatic Knee Injuries

Background: acute patellar dislocation is a common injury, with up to 40% of the cases missed due to a high rate of spontaneous reduction. complications mainly arise due to osteochondral fractures, resulting in patellofemoral osteoarthritis and rupture of medial patellar stabilizers, leading to recurrent patellar instability. methods: institutional database was retrospectively reviewed to find patients with missed transient patellar dislocation. from january 2010 to january 2015, ten otherwise healthy patients with a history of indirect trauma to the knee were diagnosed with missed patellar dislocation. they all had persistent pain and effusion, despite conservative treatment. results: eight patients eventually underwent arthroscopic debridement of osteochondral fractures and repair of ruptured ligaments, with no case of recurrent instability. conclusions: detailed history taking and physical examination of all acute knee injuries, with a standard three dimensional (3d) x-ray imaging and a low threshold to obtain magnetic resonance imaging (mri) studies, could minimize cases of missed patellar dislocation and possibly severe complications.