Fact-sheet: Patellar dislocation
Updated on 09/17/2021 at 12:16 PM
View all RADEOS cases associated with this fact-sheet
Definition
Patellar dislocation occurring in young athletes during a movement combining internal rotation and Knee flexion during quadriceps contraction (fixed foot), favored by trochlear dysplasia, and often associated with:
- medial meniscus tear
- ligamentous injuries
Radiography
Establishes the diagnosis of dislocation.
Associated findings (inconstant):
- Intra-articular effusion
- Fracture
- Trochlear dysplasia
MRI
Intra-articular effusion - Hemarthrosis
Partial or complete tear, or avulsion of the medial patellar retinaculum
Subchondral bone contusion, hypointense on T1 and hyperintense on T2, in a mirror-image pattern on the medial aspect of the patella and on the lateral aspect of the femoral condyle
Residual lateral displacement of the patella
Search for associated lesions:
- Medial meniscus tear
- Ligamentous injuries
Management
Temporary immobilization followed by rehabilitation.
If unsuccessful: surgery = fixation of osteochondral fragments, repair of the medial capsule, lateral retinacular release, realignment of the vastus medialis and vastus lateralis