title: The importance of CT for the pre-operative surgical planning in recurrent anterior shoulder instability.
abstract: BACKGROUND
  MRI is the current pre-operative imaging standard in recurrent anterior shoulder instability; however, CT has increasingly gained interest due to its advantages in the detection of bony glenoid defects. This study compares the value of CT imaging and MRI for pre-operative surgical planning in recurrent anterior shoulder instability.
  
  
  METHODS
  Between 2006 and 2009, 83 patients presented to the author's department with recurrent anterior shoulder instability. For 48 patients, both, pre-operative MRI and CT images were available. The respective patho-morphological descriptions were retrospectively compared with the intra-operative findings. The effect of each imaging technique on the pre-operative surgical planning was analyzed and the accuracy in predicting the necessity of open versus arthroscopic surgery was compared.
  
  
  RESULTS
  In determining the necessity of open versus arthroscopic surgery CT imaging rendered an inaccurate prediction in 4.8 % of the cases which is less than the 25.0 % calculated for MRI. (p = 0.019). MRI showed a low sensitivity (35.3 %) in the detection of significant glenoid bone defects (≥20 % of the glenoid width measured on en-face views using a best-fit circle technique) while CT imaging provided an accurate prediction of the intra-operative finding in all cases.
  
  
  CONCLUSIONS
  Despite the advantages of MRI in the detection of soft tissue damages in recurrent anterior shoulder instability CT imaging proved to be more important for pre-operative planning by prevailing in the detection of glenoid defects. Therefore, the replacement of MRI as preoperative imaging standard with CT imaging is recommended.
authors.affiliation: Department of Traumatology and Sports Injuries, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020, Salzburg, Austria. philipp.moroder@pmu.ac.at
authors.forename: Philipp
authors.initials: P
authors.lastname: Moroder
authors.forename: Herbert
authors.initials: H
authors.lastname: Resch
authors.forename: Silke
authors.initials: S
authors.lastname: Schnaitmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Hoffelner
authors.forename: Mark
authors.initials: M
authors.lastname: Tauber
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D057234:Preoperative Period; D012008:Recurrence; D012189:Retrospective Studies; D012783:Shoulder Dislocation / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D012785:Shoulder Joint; D014057:Tomography, X-Ray Computed