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O'Donoghue's unhappy triad

Case contributed by Dr Mohammed ElBeialy


Knee pain, swelling and giving away for 3 months since trauma.

Patient Data:

Age: 32 years
Gender: Male
Race: Middle eastern
Modality: MRI

Bucket-handle tear of the posterior horn of medial meniscus with double PCL sign and increased intra-meniscal signal seen disrupting both articular surfaces and menisco-capsular attachment. Full thickness tear of the ACL with indistinct outline and increased signal intensity. The medial collateral ligament shows mild thickening with increased signal intensity within and around. Moderate joint effusion. The posterior lateral tibial condyle shows patchy area of marrow oedema signal demonstrating low T1 and bright PD FS and STIR signal.The popliteus muscle shows oedema signal with high T2, PDFS and STIR signal.

Case Discussion:

O'Donoghue's unhappy triad results from valgus stress with rotation of the knee. It comprises ACL tear and MCL injury (tear or sprain) with a medial meniscal tear.

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