Anterior Cruciate Ligament Rupture with Medial Collateral Ligament Tear with Lateral Meniscus Posterior Root Tear with Posterolateral Tibia Osteochondral Fracture: A New Injury Tetrad of the Knee

INTRODUCTION: Injuries to the knee ligaments, menisci, and cartilage are possible in high-velocity trauma as in road traffic accidents. Similarly, these structures can be disrupted in proximal tibia fractures. We present a series of three cases which had a previously undescribed injury combination. CASE PRESENTATION: The first and second patients presented primarily to us following fall from motorbikes. Both these patients had injuries of the anterior cruciate ligament (ACL), medial collateral ligament (MCL), lateral meniscus body and posterior root tear, and osteochondral fracture of posterolateral tibia. The osteochondral fracture was managed by internal fixation with headless compression screws. The ligaments were either repaired or reconstructed and meniscus root tear was treated by transtibial pull through repair. The third patient also had the same injury but was treated at another center. He presented with early arthritis of the lateral tibiofemoral joint and valgus malalignment. Treatment for him was in the form of lateral distal femur open-wedge osteotomy and MCL reconstruction. All three patients had good outcome at the end of 1year. CONCLUSION: We report a new injury tetrad of ACL tear, MCL tear, lateral meniscus posterior root tear, and posterolateral tibia osteochondral fracture. The mechanism of injury is most likely a violent external rotation and anterior translation of the tibia with a valgus directed force during impact. The treatment of this injury can be performed in single or two stages based on the merits of the case. Anatomic reduction and fixation of the fracture takes precedence to avoid later devastating sequel for the knee.