Anterior cruciate ligament rupture complicated by Wrisberg rip
Presentation
Sporting injury. ACL rupture?
Patient Data
Plain radiographs show a small cystic lucency in the medial femoral metaphysis, abutting the cortex dorsally, but no sign of bony trauma. The suprapatellar recess shows moderate bulging, indicating joint effusion or hemarthrosis.
Bone edema indicating bruise in both femoral and the posterolateral tibial condyles. Pattern in line with pivot-shift injury.
Complete tear of the anterior cruciate ligament, with resultant inhomogenity and wavy apperance of its bundles.
Longitudinal vertical tear of the posterior horn of the lateral meniscus, extending from the attachment of the ligament of Wrisberg.
Moderate knee joint effusion.
Minimal fluid medially, superficial to the semitendinosus and gracilis tendons.
Small cortical fluid signal cystic change at the medial gastrocnemius tendon insertion, (possibly a long-standing cortical desmoid or a small non-ossifying fibroma).
Case Discussion
The MRI exam reveals a pivot-shift injury mechanism and a combination of ACL tear and a Wrisberg rip type of lateral meniscal tear. These two injuries are commonly associated.