Lateral patellar dislocation

Case contributed by Dr Utkarsh Kabra

Presentation

History of trauma, now complaining of pain

Patient Data

Age: 15 years
Gender: Male
MRI

Osteochondral defect, measuring approx. 13mm along medial articular facet of patella with displaced cartilage fragment lying medially. It is possibly partly attached to medial facet of patella.

Osteochondral injury seen involving lateral femoral condyle with surrounding marrow edema. Bone fragment is seen, measuring approx. 21 mm, lying at lateral aspect. 

Small bone fragment measuring approx. 12 mm also seen at posteromedial aspect of lateral tibial condyle.

Intermediate grade sprain of medial patellofemoral ligament seen at patellar attachment.

Minimal edema seen involving femoral attachment of medial collateral ligament. Continuity of fibers is maintained.

Low grade sprain of posterolateral bundle of ACL seen in mid segment and femoral attachment. Fibers are as such intact.

Mild strain of vastus medialis and lateral head of gastrocnemius muscle seen.

Moderate joint effusion is seen with areas of hemorrhage. 

Significant edema and fat stranding in Hoffa’s fat pad with possible injury of infrapatellar plica.

Normal morphology and signal intensity seen in anterior and posterior horn of medial and lateral menisci.

Lateral collateral and posterior cruciate ligaments are normal.

Case Discussion

Osteochondral defect, measuring approx. 13mm along medial articular facet of patella with displaced cartilage fragment lying medially. It is possibly partly attached to medial facet of patella. Osteochondral injury seen involving lateral femoral condyle with surrounding marrow edema. Intermediate grade sprain of medial patellofemoral ligament seen at patellar attachment.

These findings are consistent with lateral patellar dislocation.

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Case information

rID: 72815
Published: 12th Dec 2019
Last edited: 16th Dec 2019
Inclusion in quiz mode: Included

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