Presentation
Recent knee trauma.
Patient Data
Cast fixation can be seen.
Post reduction plain radiograph showing good reduction of the joint with no fracture lines. Preserved joint space. 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 hemarthrosis raising the possibility of disrupted joint capsule, a findings to be confirmed by arthrography. The hemarthrosis is seen at all joint spaces including the suprapatellar space.
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. Both the medial and lateral meniscal horns show tears or degeneration.
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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