Findings:

• a small avulsed fragment at the medial rim of the patella

Impression:

• medial avulsion fracture of the patella

Findings:

• large knee joint effusion

Intercondylar region:

• unremarkable anterior and posterior cruciate ligaments
• two loose chondral fragments between the anterior transverse meniscal ligament and the intercondylar groove

Medial compartment:

• unremarkable cartilage and medial meniscus
• soft tissue edema
• thickening of the superficial part of the medial collateral ligament small tear within the proximal part

Lateral compartment:

• bone contusion of the anterolateral rim of the lateral femoral condyle
• extensive chondral lesion of the antero- and centrolateral femoral cartilaginous zone with delamination
• normal lateral collateral ligament and posterolateral corner

Patellofemoral compartment:

• medial patellofemoral ligament tear at the patellar and femoral attachment with nondisplaced osteochondral avulsion fracture at the inferomedial patella margin
• fluid extending into the vastus medialis myotendinous junction
• shallow trochlear groove
• Hoffa fat pad edema 

Impression:

Typical findings of prior lateral patellar dislocation:

• medial patellofemoral ligament tear at the patellar and femoral attachment with osteochondral avulsion fracture at the inferomedial patellar margin
• two intraarticular chondral fragments
• extensive chondral lesion of the antero- and centrolateral femoral condyle
• traumatic changes of the Hoffa fat pad
• decreased trochlear depth indicating trochlear dysplasia

Key findings:

• bone bruises of inferomedial patella (blue arrowhead) and the anterolateral femoral condyle (blue arrows)

• patellar lateralization (blue double arrow)

• medial patellar avulsion fracture with an unstable osteochondral fragment (purple arrow)

• medial patellofemoral ligament with a partial tear of the patellar insertion (red arrow) and disruption of the femoral attachment (red arrowheads)

• edema and myotendinous tear of the vastus medialis oblique (VMO) (green arrow)

• two chondral fragments (purple arrowheads) between the anterior transverse meniscal ligament and the intercondylar groove

• chondral lesion of the antero- and centrolateral femoral condyle (orange arrowheads) with delamination

Assessment for risk factors:

• Insall-Salvati index ≈ 1,3 - borderline

• decreased trochlear depth (<3mm)

• lateral trochlear inclination (LTI) and trochlear facet ratio within normal limits

• TT-TG < 15mm