title: Disk abnormality coexists with any degree of synovial and osseous abnormality in the temporomandibular joints of children with juvenile idiopathic arthritis.
abstract: BACKGROUND
  MRI manifestation of temporomandibular joint arthritis is frequently reported in children with juvenile idiopathic arthritis. However, little attention has been paid to temporomandibular joint disk abnormalities.
  
  
  OBJECTIVE
  To assess combinations of MRI findings in the symptomatic temporomandibular joint in children with juvenile idiopathic arthritis with focus on disk abnormalities.
  
  
  METHODS
  This was a retrospective study of 46 patients with juvenile idiopathic arthritis, mean age 12 years (range: 5-17 years). Mean disease duration was 70 months (standard deviation: 61 months). MR images of 92 temporomandibular joints were scored for thickness of abnormally enhancing synovium (synovitis), joint effusion, bone marrow oedema, abnormal bone shape, bone erosion and disk abnormalities.
  
  
  RESULTS
  The 92 temporomandibular joints were categorized as A: No synovitis and normal bone shape (30/92; 33%), B: Synovitis and normal bone shape (14/92: 15%), C: Synovitis and abnormal bone shape (38/92; 41%) and D: No synovitis but abnormal bone shape (10/92; 11%). Thirty-six of the 46 patients (78%) had synovitis and 33/46 (72%) had abnormal bone shape, most frequently in combination (30/46; 65%). Disk abnormalities (flat disk, fragmented disk, adherent disk and displaced disk) were found in 29/46 patients (63%). Disk abnormalities were found in all categories of juvenile idiopathic arthritis involved temporomandibular joints (B: 8/14 [57%]; C: 25/38 [66%] and D: 7/10 [70%]). Disk displacement was found in half of the joints (7/14) in category B. Synovitis was most pronounced in this category.
  
  
  CONCLUSIONS
  Disk abnormalities were frequent. Disk displacement also occurred in joints with early temporomandibular joint arthritis, i.e., with normal bone shape. Other disk abnormalities were found in joints with bone abnormalities. Attention should be paid to disk abnormalities both in early and long-standing temporomandibular joint arthritis in children with juvenile idiopathic arthritis.
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Rikshospitalet, Postbox 4950, Nydalen, N-0424, Oslo, Norway. eva.kirkhus@medisin.uio.no.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway. eva.kirkhus@medisin.uio.no.
authors.forename: Eva
authors.initials: E
authors.lastname: Kirkhus
authors.affiliation: Department of Maxillofacial Radiology, Institute of Clinical Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Linda Z
authors.initials: LZ
authors.lastname: Arvidsson
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Rikshospitalet, Postbox 4950, Nydalen, N-0424, Oslo, Norway.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors.forename: Hans-Jørgen
authors.initials: HJ
authors.lastname: Smith
authors.affiliation: Department of Rheumatology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors.forename: Berit
authors.initials: B
authors.lastname: Flatø
authors.affiliation: Department of Rheumatology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors.forename: Siri O
authors.initials: SO
authors.lastname: Hetlevik
authors.affiliation: Department of Maxillofacial Radiology, Institute of Clinical Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Tore A
authors.initials: TA
authors.lastname: Larheim
mesh_terms: D000293:Adolescent; D001171:Arthritis, Juvenile / Q000000981:diagnostic imaging* / Q000473:pathology; D001847:Bone Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007568:Jaw / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013585:Synovitis / Q000000981:diagnostic imaging* / Q000473:pathology; D019224:Temporomandibular Joint Disc / Q000000981:diagnostic imaging* / Q000473:pathology; D013705:Temporomandibular Joint Disorders / Q000000981:diagnostic imaging* / Q000473:pathology
keywords: Child; Juvenile idiopathic arthritis; Magnetic resonance imaging; Synovitis; Temporomandibular joint