title: Coccygeal movement: assessment with dynamic MRI.
abstract: OBJECTIVE
  Chronic coccygodynia is a difficult problem diagnostically and therapeutically. Moreover, there is no deep knowledge especially in the field of imaging of chronic coccygodynia. In this study several possible measurements are proposed, which all are able to demonstrate coccygeal movement during defecation, in order to assess coccygeal mobility using dynamic MRI during maximum contraction and during straining-evacuation.
  
  
  METHODS
  A dynamic MRI study of the pelvic floor was performed in 112 patients. Five methods of measurement were assessed. Coccygeal movements were determined through the evaluation of three angles pair and two different distances measured during the phase of maximum contraction and during the phase of straining-evacuation. Results were compared according to age, sex, parity and experience of minor trauma. No patient included in the study had coccygodynia. Measurements taken by two radiologist were compared to determine interobserver agreement.
  
  
  RESULTS
  The maximum measurement values of the two distances are homogeneous, between 9 and 9.4mm. The maximum measurement values of the three angles showed a difference that is between 21 degrees and 38 degrees . Two of three angles showed a major measurement values in the funtional texts. In only one patient the coccyx was not mobile.
  
  
  CONCLUSIONS
  Our dynamic MRI study indicates that the coccyx is mobile during defecation and that it is possible to demonstrate coccygeal excursions by assessing the difference between its positions at maximum contraction and during straining-evacuation. The measurement methods used in this study for evaluating coccygeal movements resulted in variably sized observed differences, but all yielded statistically significant results in demonstrating coccygeal excursion. Among the five measurement methods, two resulted in the largest differences. Our data indicate no correlation between coccygeal movements and age, sex, parity, minor trauma and coccygodynia.
authors.affiliation: Institute of Radiology, Second University of Naples, Piazza Miraglia, 80138 Naples, Italy. Roberto.grassi@unina2.it
authors.forename: Roberto
authors.initials: R
authors.lastname: Grassi
authors.forename: Giulio
authors.initials: G
authors.lastname: Lombardi
authors.forename: Alfonso
authors.initials: A
authors.lastname: Reginelli
authors.forename: Francesco
authors.initials: F
authors.lastname: Capasso
authors.forename: Francesco
authors.initials: F
authors.lastname: Romano
authors.forename: Irene
authors.initials: I
authors.lastname: Floriani
authors.forename: Nicola
authors.initials: N
authors.lastname: Colacurci
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003050:Coccyx / Q000293:injuries / Q000473:pathology* / Q000503:physiopathology; D019841:Defecography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D010298:Parity; D017699:Pelvic Pain / Q000209:etiology*; D011247:Pregnancy; D014949:Wounds, Nonpenetrating