Entrapped lateral meniscus in tibial plateau fracture

Case contributed by Julia Mansour
Diagnosis certain

Presentation

Patient slipped down three steps and fell on to her right side. She heard a loud pop coming from the right leg at the time of the injury followed by pain.

Patient Data

Age: 50 years
Gender: Female

Radiographs of the right knee demonstrate a bicondylar tibial plateau fracture, including a vertical fracture line extending through/just lateral to the tibial spines and a transverse fracture line at the medial tibial diametaphysis. There is a narrowing of the lateral compartment joint space. A fibular head fracture and lipohemarthrosis are seen on the cross-table lateral view.

The circular density is external to the patient.

MRI of the right knee demonstrates a comminuted proximal tibial fracture with involvement of both the medial and lateral tibial plateau. There is a posteriorly displaced proximal tibial metaphyseal fragment with a large portion of the lateral meniscus coiled within a fracture gap. There is a displaced fracture of the posteromedial fibular head and extensive posterolateral corner injury. Lipohemarthrosis is seen with a fat-fluid level in the suprapatellar recess. The medial meniscus and the ligaments of the knee are intact. The cruciate ligaments are attached to the posteriorly displaced proximal tibial fragment. There is extensive soft tissue edema.

Case Discussion

Tibial plateau fractures typically occur with a bimodal distribution due to high-energy trauma in the young and low-energy trauma in the elderly. Soft tissue injury may be associated with these fractures, with the lateral meniscus most commonly involved, followed by the cruciate ligaments, medial meniscus, and collateral ligaments. These soft tissue injuries are usually not visible on radiographs so an MRI may be considered before fracture fixation.

Meniscal entrapment in the tibial fracture was confirmed at the time of surgery. Excerpt from the operative report:

"The lateral meniscus was completely entrapped within the fracture. This was mobilized and retrieved from the fracture such that it then sat back in the lateral compartment. 3-0 PDS sutures were used in horizontal mattress fashion through the capsule, across the meniscal rim, and back through the capsule to attach the meniscus back to its capsular junction. Despite this, the meniscus did have evidence of nonrepairable traumatic injury at its most anterior aspect."

Case co-author: Karissa Jackson (Loyola University)

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