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What are the main medial patellar stabilizers?
The medial patellofemoral complex with the medial patellofemoral ligament, the medial retinaculum and the medial vastus obliquus (VMO).
What are considered as risk factors for patellofemoral instability?
Patella alta, trochlear dysplasia, increased TT-TG distance.
What is the clinical significance of those risk factors?
Surgical repair should be considered, even in a first- time dislocation
Findings:
- large, predominantly suprapatellar joint effusion
Intercondylar Region:
- unremarkable anterior and posterior cruciate ligaments
Medial compartment:
- unremarkable cartilage and medial meniscus
- soft tissue oedema above the normal medial collateral ligament
Lateral compartment:
- bone contusion at the anterolateral aspect of the lateral femoral condyle
- unremarkable cartilage and lateral meniscus
- normal lateral collateral ligament and posterolateral corner
Patellofemoral compartment:
- small osseous avulsion of the medial patella rim
- thickened, oedematous medial patellofemoral ligament
- fluid extending into the vastus medialis myotendinous junction
- shallow trochlear groove, lateral trochlear inclination (LTI) was borderline 11-12°
Impression:
Typical findings of previous lateral patellar dislocation:
- medial patellofemoral ligament injury with bony avulsion of the patellar insertion and tear of the femoral origin
- tear of the medial retinaculum and vastus medialis oblique (VMO)
- bone contusion of the anterolateral femoral condyle
- decreased trochlear depth indicating trochlear dysplasia
- patella alta