Extensive internal derangement of the knee

Case contributed by Dr Mahmoud Yacout Alabd


Recent knee trauma.

Patient Data

Age: 36
Gender: Male

Post reduction plain radiograph showing good reduction of the joint with no fracture lines. The only abnormal finding is high riding patella on the lateral projection. 

The MRI shows marked amount of intra articular fluid that reflects heterogeneous signal intensity with some bright T1 signal and some iso to low T2 signal denoting blood products of different chronological ages some of which is acute in nature. Extra-articular fluid/hematoma on the medial aspect with suspected communication with the haemarhtrosis raising the possibility of disrupted joint capsule, a findings to be confirmed by arthrography. Marked related soft tissue and skin edema is also seen. Both the PCL and ACL are completely disrupted. Coronal cuts also revealed torn medial collateral ligament. The patella is seen high in location on sagittal plane, however the patellar ligaments are intact, likely to be displaced by the significant intra articular fluid.

Case Discussion

The patient presented with recent trauma to the right lower limb with consequent tibiofemoral dislocation of the knee joint. Immediate surgical reduction was performed and this MRI was done after. 

The tibiofemoral type of knee dislocation is less frequent as compared patellar dislocation. However, it is considered to be an emergency due to the high possibility of associated vascular injuries or compromise, which can threaten the viability of the limb. There is almost always an associated injury to the main ligaments of the knee: the cruciate ligaments are usually always disrupted, together with one or both of the collateral ligaments. This case demonstrates both cruciate ligaments, and medial collateral ligament injuries.

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Case information

rID: 39945
Published: 29th Sep 2015
Last edited: 16th Jul 2018
Inclusion in quiz mode: Included

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