title: A CT scan protocol for the detection of radiographic loosening of the glenoid component after total shoulder arthroplasty.
abstract: OBJECTIVE
  It is difficult to evaluate glenoid component periprosthetic radiolucencies in total shoulder arthroplasties (TSAs) using plain radiographs. This study was performed to evaluate whether computed tomography (CT) using a specific patient position in the CT scanner provides a better method for assessing radiolucencies in TSA.
  
  
  METHODS
  Following TSA, 11 patients were CT scanned in a lateral decubitus position with maximum forward flexion, which aligns the glenoid orientation with the axis of the CT scanner. Follow-up CT scanning is part of our routine patient care. Glenoid component periprosthetic lucency was assessed according to the Molé score and it was compared to routine plain radiographs by 5 observers.
  
  
  RESULTS
  The protocol almost completely eliminated metal artifacts in the CT images and allowed accurate assessment of periprosthetic lucency of the glenoid fixation. Positioning of the patient within the CT scanner as described was possible for all 11 patients. A radiolucent line was identified in 54 of the 55 observed CT scans and osteolysis was identified in 25 observations. The average radiolucent line Molé score was 3.4 (SD 2.7) points with plain radiographs and 9.5 (SD 0.8) points with CT scans (p = 0.001). The mean intra-observer variance was lower in the CT scan group than in the plain radiograph group (p = 0.001).
  
  
  CONCLUSIONS
  The CT scan protocol we used is of clinical value in routine assessment of glenoid periprosthetic lucency after TSA. The technique improves the ability to detect and monitor radiolucent lines and, therefore, possibly implant loosening also.
authors.affiliation: Department of Orthopaedic Surgery, University Paris Descartes, European Hospital Georges Pompidou, APHP, Paris, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gregory
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hansen
authors.forename: Monica
authors.initials: M
authors.lastname: Khanna
authors.forename: Celine
authors.initials: C
authors.lastname: Mutchler
authors.forename: Saik
authors.initials: S
authors.lastname: Urien
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Amis
authors.forename: Bernard
authors.initials: B
authors.lastname: Augereau
authors.forename: Roger
authors.initials: R
authors.lastname: Emery
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement / Q000009:adverse effects*; D016477:Artifacts; D002985:Clinical Protocols; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000601:surgery; D010014:Osteolysis / Q000209:etiology; D056888:Patient Positioning / Q000379:methods; D011475:Prosthesis Failure; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods