title: Temporomandibular joint (TMJ) disc position in patients with TMJ pain assessed by coronal MRI.
abstract: OBJECTIVE
  To assess the position of the temporomandibular joint (TMJ) disc in patients with TMJ pain and compare it with equivalent published data of asymptomatic volunteers.
  
  
  METHODS
  The oblique coronal closed- and open-jaw MR images from 66 patients with TMJ pain were evaluated. Clinical examination followed the research diagnostic criteria for temporomandibular disorders. In all coronal images, the transverse condylar axis and the medial and lateral edges of the disc were determined using special software. Inter-rater agreement was calculated [two raters; inter-rater correlation coefficient (ICC)]. The presence of osteoarthrosis (OA) was determined by two independent raters. The influence of OA was estimated in patients (generalized estimation equation model). The results were compared with those of healthy volunteers (t-test). Differences between closed and open jaw in patients were analysed with the Wilcoxon matched-pair test.
  
  
  RESULTS
  The ICC was good for the transverse condylar axis (0.987) and the medial edge of the disc (0.799) and fair for the lateral edge (0.355). On average, the disc projected 5.5% to the medial side; laterally, the condyle was partially uncovered by the disc (-16.6%). In the open-jaw position, both the medial and the lateral edges shifted medially (to 17.6% vs -23.6%, Wilcoxon matched-pair test, p < 0.001). OA had no significant influence (generalized estimation equation model, p = 0.952). The disc position differed significantly from asymptomatic individuals (t-test, p < 0.001) who showed a medial disc position and full coverage of the condyle.
  
  
  CONCLUSIONS
  In patients with TMJ pain, the disc seems to be smaller and located less medially than in healthy volunteers. The extent of the medial shift on opening was similar.
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Germany. lydial.eberhard@med.uni-heilberg.de
authors.forename: L
authors.initials: L
authors.lastname: Eberhard
authors.forename: N N
authors.initials: NN
authors.lastname: Giannakopoulos
authors.forename: S
authors.initials: S
authors.lastname: Rohde
authors.forename: M
authors.initials: M
authors.lastname: Schmitter
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005157:Facial Pain / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008335:Mandibular Condyle / Q000473:pathology; D008875:Middle Aged; D015588:Observer Variation; D010003:Osteoarthritis / Q000175:diagnosis; D016059:Range of Motion, Articular / Q000502:physiology; D012189:Retrospective Studies; D019224:Temporomandibular Joint Disc / Q000473:pathology*; D013705:Temporomandibular Joint Disorders / Q000175:diagnosis*; D055815:Young Adult
keywords: magnetic resonance imaging; osteoarthritis; temporomandibular joint; temporomandibular joint disc; temporomandibular joint disorders