title: Posteromedial Corner of the Knee: The Neglected Corner.
abstract: The posteromedial corner of the knee (PMC) is an important anatomic structure that is easily seen but often overlooked on magnetic resonance (MR) images. Whereas the posterolateral corner has been referred to as the "dark side of the knee" by some authors owing to widespread lack of knowledge of its complex anatomy, even less is written about the PMC; yet it is as important as the posterolateral corner in multiligament injuries of the knee. The PMC lies between the posterior margin of the longitudinal fibers of the superficial medial collateral ligament (MCL) and the medial border of the posterior cruciate ligament (PCL). The anatomy of the PMC can be complex and the literature describing it can be confusing, at times oversimplifying it and at other times adding unnecessary complexity. Its most important structures, however, can be described more simply as five major components, and can be better shown with illustrations that emphasize the anatomic distinctions. Injuries to the PMC are important to recognize, as disruption of the supporting structures can cause anteromedial rotational instability (AMRI). Isolated PMC injuries are rare; most occur in conjunction with injuries to other important stabilizing knee structures such as the anterior cruciate ligament (ACL) and PCL. Unrecognized and unaddressed injury of the PMC is one of the causes of ACL and PCL graft failures. Recognition of PMC injuries is critical, as the diagnosis will often change or require surgical management.
authors.affiliation: From the Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo St, Los Angeles, CA 90033 (R.B.L., G.R.M., A.J.S., E.A.W., D.M.F., D.B.P.); Department of Radiology, Southern California University of Health Sciences, Whittier, Calif (M.R.S.); and Department of Radiology, NYU Langone Medical Center, New York, NY (C.J.G.).
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Lundquist
authors.affiliation: From the Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo St, Los Angeles, CA 90033 (R.B.L., G.R.M., A.J.S., E.A.W., D.M.F., D.B.P.); Department of Radiology, Southern California University of Health Sciences, Whittier, Calif (M.R.S.); and Department of Radiology, NYU Langone Medical Center, New York, NY (C.J.G.).
authors.forename: George R
authors.initials: GR
authors.lastname: Matcuk
authors.affiliation: From the Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo St, Los Angeles, CA 90033 (R.B.L., G.R.M., A.J.S., E.A.W., D.M.F., D.B.P.); Department of Radiology, Southern California University of Health Sciences, Whittier, Calif (M.R.S.); and Department of Radiology, NYU Langone Medical Center, New York, NY (C.J.G.).
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Schein
authors.affiliation: From the Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo St, Los Angeles, CA 90033 (R.B.L., G.R.M., A.J.S., E.A.W., D.M.F., D.B.P.); Department of Radiology, Southern California University of Health Sciences, Whittier, Calif (M.R.S.); and Department of Radiology, NYU Langone Medical Center, New York, NY (C.J.G.).
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Skalski
authors.affiliation: From the Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo St, Los Angeles, CA 90033 (R.B.L., G.R.M., A.J.S., E.A.W., D.M.F., D.B.P.); Department of Radiology, Southern California University of Health Sciences, Whittier, Calif (M.R.S.); and Department of Radiology, NYU Langone Medical Center, New York, NY (C.J.G.).
authors.forename: Eric A
authors.initials: EA
authors.lastname: White
authors.affiliation: From the Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo St, Los Angeles, CA 90033 (R.B.L., G.R.M., A.J.S., E.A.W., D.M.F., D.B.P.); Department of Radiology, Southern California University of Health Sciences, Whittier, Calif (M.R.S.); and Department of Radiology, NYU Langone Medical Center, New York, NY (C.J.G.).
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Forrester
authors.affiliation: From the Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo St, Los Angeles, CA 90033 (R.B.L., G.R.M., A.J.S., E.A.W., D.M.F., D.B.P.); Department of Radiology, Southern California University of Health Sciences, Whittier, Calif (M.R.S.); and Department of Radiology, NYU Langone Medical Center, New York, NY (C.J.G.).
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Gottsegen
authors.affiliation: From the Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo St, Los Angeles, CA 90033 (R.B.L., G.R.M., A.J.S., E.A.W., D.M.F., D.B.P.); Department of Radiology, Southern California University of Health Sciences, Whittier, Calif (M.R.S.); and Department of Radiology, NYU Langone Medical Center, New York, NY (C.J.G.).
authors.forename: Dakshesh B
authors.initials: DB
authors.lastname: Patel
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000473:pathology*; D000070598:Anterior Cruciate Ligament Injuries; D001265:Athletic Injuries / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D055815:Young Adult