title: Mechanism-based pattern approach to classification of complex injuries of the knee depicted at MR imaging.
abstract: Complex knee injuries are common, often resulting from multiple forces: varus, valgus, hyperextension, hyperflexion, internal rotation, external rotation, anterior or posterior translation, and axial load. Certain combinations of forces are known to cause specific injury patterns. After a review of the literature, the authors developed a mechanism-based classification system based on patterns of bone marrow edema and ligament injury for complex knee injuries depicted at magnetic resonance imaging. The classification system takes into account knee position and forces and recognition of patterns of bone injury and complementary soft-tissue injury. Ten mechanism-based injury patterns were recognized: (a) pure hyperextension, (b) hyperextension with varus, (c) hyperextension with valgus, (d) pure valgus, (e) pure varus, (f) flexion with valgus and external rotation, (g) flexion with varus and internal rotation, (h) flexion with posterior tibial translation, (i) patellar dislocation (flexion, valgus, and internal rotation of femur on fixed tibia), and (j) direct trauma. Recognition of these patterns may help assess the full extent of knee injury, particularly at the posterolateral and posteromedial corners of the knee.
authors.affiliation: Department of Radiology, University of Michigan Health System, Taubman Center, Rm 2910A, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0326, hayescw@umich.edu
authors.forename: C W
authors.initials: CW
authors.lastname: Hayes
authors.forename: M K
authors.initials: MK
authors.lastname: Brigido
authors.forename: D A
authors.initials: DA
authors.lastname: Jamadar
authors.forename: T
authors.initials: T
authors.lastname: Propeck
mesh_terms: D000070598:Anterior Cruciate Ligament Injuries; D001855:Bone Marrow Diseases / Q000175:diagnosis; D004487:Edema / Q000175:diagnosis; D006801:Humans; D004204:Joint Dislocations / Q000175:diagnosis; D007718:Knee Injuries / Q000145:classification* / Q000175:diagnosis / Q000209:etiology; D007719:Knee Joint / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D017888:Medial Collateral Ligament, Knee / Q000293:injuries; D010329:Patella / Q000293:injuries; D016119:Posterior Cruciate Ligament / Q000293:injuries; D012189:Retrospective Studies; D012399:Rotation; D017695:Soft Tissue Injuries / Q000175:diagnosis; D013314:Stress, Mechanical; D016474:Weight-Bearing