title: MRI of pediatric patients: Part 2, normal variants and abnormalities of the knee.
abstract: OBJECTIVE
  The purpose of this article is to discuss MRI of the pediatric knee and familiarize the reader with conditions encountered in the pediatric population. Clinical scenarios are included to convey important concepts and to orient the learner to normal variants and abnormalities of the pediatric knee. The conditions discussed include, but are not limited to, distal femoral metaphysial irregularity, isolated popliteus tendon avulsion, juvenile idiopathic arthritis, and discoid meniscus.
  
  
  CONCLUSIONS
  The knee is the joint that is most commonly imaged by MRI in children. Injury patterns and signs of other pathologic processes seen in skeletally immature patients are different from those seen in adults. Interpreting pediatric knee MRI studies may be a challenge for those unfamiliar with the evolving patterns of normal development and of the signs of conditions that are more prevalent in children. Through case scenarios, this article describes and provides images that depict conditions commonly encountered in the pediatric knee. Most of the described normal findings and abnormalities are more prevalent in the pediatric population than in adults, and a few of the conditions are, in fact, unique to pediatric patients.
authors.affiliation: Department of Radiology, University of Washington & Seattle Children's Hospital, 98105-3901, USA. thapamd@u.washington.edu
authors.forename: Mahesh M
authors.initials: MM
authors.lastname: Thapa
authors.forename: Apeksha
authors.initials: A
authors.lastname: Chaturvedi
authors.forename: Ramesh S
authors.initials: RS
authors.lastname: Iyer
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Darling
authors.forename: Paritosh C
authors.initials: PC
authors.lastname: Khanna
authors.forename: Gisele
authors.initials: G
authors.lastname: Ishak
authors.forename: Felix S
authors.initials: FS
authors.lastname: Chew
mesh_terms: D000293:Adolescent; D002357:Cartilage Diseases / Q000175:diagnosis* / Q000473:pathology; D002358:Cartilage, Articular / Q000033:anatomy & histology / Q000293:injuries*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007592:Joint Diseases / Q000175:diagnosis* / Q000473:pathology; D007718:Knee Injuries / Q000175:diagnosis* / Q000473:pathology; D007719:Knee Joint / Q000033:anatomy & histology / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012016:Reference Values