ACL, medial meniscus and MCL tear : myriad of classic pivot shift injury

Case contributed by Dr Nafisa Shakir Batta

Presentation

Football injury, unstable knee with pain and locking

Patient Data

Age: 25 years
Gender: Male

Complete ACL transection is seen with surrounding T2 hyperintensity and presence of moderate volume synovial effusion in the tibiofemoral, patellofemoral and suprapatellar spaces.

The medial meniscus is discontinuous at anterior and outer horn, with absent bow tie sign, and a continuous displaced bucket handle tear, and fragment lying posteriorly over the posterior horn, simulating the flipped meniscus sign or disproportionate posterior horn sign.

The superficial and deep fibres of the medial collateral ligament ( MCL) are torn and edematous.

The triad of ACL, MM and MCL tear is referred to as the O'Donaghue triad.

The lateral collateral ligament complex also shows interfibrillary edema at the arcuate ligament and at fibular attachment. Diffuse edema is seen at posterolateral joint capsule , with hemorrhage around the soleus muscle.

The lateral tibial and femoral condyles reveal kissing contusions with marrow edema at posterior aspect of tibia. A depressed lateral femoral osterochondral fracture is seen measuring 11x4 mm - type 2 osteochondral injury with lateral femoral notch sign.

The  medial and lateral patellar retinacula also show edema.

Case Discussion

Complete ACL tear is seen with a bucket handle tear of  medial meniscus which shows posterior displacement of the anterior horn to lie  posteriorly ( flipped meniscus sign).

The medial collateral ligament shows a high grade tear with osteochondral fracture of lateral femoral condyle and moderate synovial effusion.

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