Lateral patellar dislocation

Dr Ian Bickle and Dr Aditya Shetty et al.

Lateral patellar dislocation refers to lateral displacement followed by dislocation of patella due to disruptive changes to the medial patellar retinaculum.

Patellar dislocation accounts for ~3% of all knee injuries and is commonly seen in those individuals who participate in sport activities.

Patella dislocation most commonly results from a twisting motion, with the knee in flexion and the femur rotating internally on a fixed foot (valgus-flexion-external rotation) 1.

  • lateral displacement of patella noted on skyline projection
  • joint effusion
  • sliver sign

The following features are noted:

  • medial retinacular abnormalities (ranging from strain to complete disruption ) with adjacent periligamentous edema and haemorrhage
  • lateral displacement of patella
  • medial patellar contusion +/- corresponding lateral femoral condyle contusion
  • joint effusion

The presence of an abnormal medial retinaculum should suggest the diagnosis of transient lateral patellar dislocation 1.

  • acute ACL tear: no medial patella contusion in this injury
  • direct trauma to lateral knee: normally no patellar contusion 4
Knee pathology

The knee is a complex synovial joint that can be affected by a range of pathologies:

Share article

Article information

rID: 27273
Section: Pathology
Synonyms or Alternate Spellings:
  • Transient lateral patellar dislocation

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Figure 1
    Drag here to reorder.
  • Drag
    Case 1
    Drag here to reorder.
  • Drag
    Case 2
    Drag here to reorder.
  • Drag
    Case 3
    Drag here to reorder.
  • Drag
    PD FS
    Case 4
    Drag here to reorder.
  • Drag
    Case 5
    Drag here to reorder.
  • Drag
    Case 6
    Drag here to reorder.
  • Drag
    Case 7
    Drag here to reorder.
  • Drag
    Case 8: relocated
    Drag here to reorder.
  • Drag
    Case 9: torn medial patellar retinaculum
    Drag here to reorder.
  • Drag
    Case 10
    Drag here to reorder.
  • Drag
    Case 11
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.