Presentation
Felt a "popping" sensation after landing on a straightened knee.
Patient Data
Moderate knee joint effusion.
High signal well within the intercondylar notch with a partial-thickness tear inferiorly of the femoral insertion of the posterior cruciate ligament (best see on the coronal sequence). Anterior cruciate, and medial and lateral collateral ligaments are intact. No meniscal tear.
Mild high signal of the distal semimembranosus insertion, however, the remaining posteromedial corner structures appear uninjured. Extensive posterior capsular edema in keeping with a hyperextension injury.
Bone marrow edema and low T1 signal through the proximal tibial epiphysis anteriorly associated periosteal edema. Effusion in the adjacent deep infrapatellar bursa. Minor focus of edema in the anterior aspect of the lateral femoral condyle.
Muscle belly edema within the fibular attachment of the soleus with periosteal stripping of the posterior fibula. Moderate edema at the gastrocnemius/soleus interface and overlying the superficial medial gastrocnemius proximal myotendinous junction.
Case Discussion
This case demonstrates a hyperextension knee injury consisting of
- partial posterior cruciate ligament tear
- proximal tibia epiphysis bone contusion and minor "kissing contusion" of the lateral femoral condyle
- posterior soft tissue injuries involving the knee joint capsule, fibular attachment of soleus and distal semimembranosus tendon