Rare case of Pivot shift phenomenon with unusual tibial plateau fracture: A report

Tibial plateau fractures are common fractures which are often associated with concurrent soft tissue injury and for which accurate preoperative diagnosis is important for development of an appropriate treatment plan and outcome prediction.

Ellen Y. Chang et al present an extreme manifestation of the pivot shift phenomenon with an unusual tibial plateau fracture with flipped component not described by any existing tibial plateau fracture classification system and never reported previously in conjunction with an anterior cruciate ligament injury.

A 17-year-old girl presented with moderate to severe right knee pain following a dirt biking accident. On physical exam, the patient noted pain with range of motion of the right knee without neurologic deficit. She was also unable to fully extend her right knee actively or passively.

Initial radiographs demonstrated a displaced right posterolateral tibial plateau fracture with the tibial plateau fracture fragment flipped 180 degrees and rotated into the anterolateral joint space. CT depicted the size and shape of the articular surface fragment and donor site. Given the unique injury pattern and high suspicion of associated soft tissue injury, an MRI was performed to evaluate the full extent of the injury for operative planning.

MRI demonstrated a comminuted, displaced posterolateral tibial plateau fracture with the dominant fracture fragment measuring 2.8 cm in maximum dimension with displacement of the fracture fragment into the anterolateral joint space. The MRI demonstrated multiple additional soft tissue injuries, including complete rupture of the anterior cruciate ligament, tear of the medial collateral ligament, tear of the fibular collateral ligament, tear of the medial patellofemoral retinaculum, and tear of the arcuate ligament and posterolateral capsule. Importantly, the MRI also demonstrated the relationship of the lateral meniscus to the displaced posterolateral tibial plateau fracture fragment. The anterior and posterior roots of the lateral meniscus remained attached at their native tibial footprints, but the lateral meniscus was elevated from the normal position, and the meniscus body was draped over and encircled the displaced bone fragment. There was also short vertical tear of the posterior horn and truncation, maceration of the body of the lateral meniscus, contusion of the fibular head and sprain of the popliteus and lateral head of the gastrocnemius muscles.

The patient was placed in a knee immobilizer and returned for operative management a few days following her initial injury.

Open submeniscal arthrotomy was performed as the lateral tibial plateau fracture fragment was identifed on arthroscopy but was not reducible arthroscopically.

The displaced lateral tibial plateau fracture fragment was identifed with bucketed lateral meniscus and intact anterior and posterior lateral meniscus roots. A universal distractor was applied to open the knee joint through an anterolateral approach; this allowed for direct manipulation, reduction and fixation of the posterolateral tibial plateau fracture.

The displaced lateral tibial plateau fracture fragment was then reduced and fixed with screws, and the lateral meniscus was reduced and repaired. The patient was placed in a hinged knee brace for conservative management of her MCL tear with plans for staged ACL reconstruction, which occurred 5 months later. Second look arthroscopy demonstrated a healed lateral tibial plateau and lateral meniscus.

Eleven months post injury and tibial plateau open reduction and internal fixation and 6 months out from anterior cruciate ligament reconstruction, the patient had no residual instability on exam, and while physical therapy was ongoing, was able to return to running.The authors concluded that - In complex and abnormal tibial plateau fractures, MRI is a valuable tool in preoperative planning as it can add important anatomic detail of the tibial plateau fracture and can add important diagnostic information regarding associated soft tissue injury. This can lead to a change in the management of these patients, which can ultimately lead to a more optimal outcome.

Further reading:

The pivot fracture: an unusual tibial plateau fracture found in association with acute ACL injury

Ellen Y. Chang, Marschall B. Berkes, Jonathan C. Baker

Skeletal Radiology (2022) 51:1697–1705

https://doi.org/10.1007/s00256-021-03962-x