title: Radiographic and computed tomography analysis of cemented pegged polyethylene glenoid components in total shoulder replacement.
abstract: BACKGROUND
  Glenoid loosening continues to be the primary reason for failure of total shoulder arthroplasty. The purpose of this study was to evaluate, with use of a sensitive and reproducible imaging method, the radiographic and clinical results of total shoulder replacement with a pegged, cemented polyethylene glenoid implant.
  
  
  METHODS
  Forty-three patients (forty-seven shoulders) underwent a total shoulder replacement with a cemented polyethylene glenoid component with four threaded pegs. The patients were examined clinically, with fluoroscopically guided radiographs, and with computed tomography at an average of forty months. In addition to conventional scoring of radiographic lucency, an 18-point scoring system was used to quantify cement-peg lucencies in six zones of the back surface of the glenoid component as seen on computed tomography scans.
  
  
  RESULTS
  On the average, the absolute Constant score improved from 39 points preoperatively to 70 points at the time of follow-up (p = 0.0001) and the pain score improved from 5 to 13 points (p = 0.001). The mean active anterior elevation improved by 34 degrees (p = 0.001) and the mean abduction, by 46 degrees (p = 0.006). Two patients had symptomatic glenoid loosening requiring revision. Twenty-one of the forty-seven shoulders had radiographic lucency around the glenoid pegs, and nine had progression of the lucency by at least two grades. Computed tomography detected lucencies, primarily at the bone-cement interface, in thirty-six shoulders. The scores for the lucencies seen on the computed tomography scans were associated with the radiographic lucency scores (p < 0.001), pain scores (p = 0.04), and abduction strength (p = 0.02). Computed tomography was more sensitive than radiography with regard to identifying the number of pegs associated with lucency and the size of the lucencies. The overall reproducibility of the scoring based on the computed tomography was higher than that of the radiographic scoring.
  
  
  CONCLUSIONS
  Computed tomography provided a more sensitive and reproducible tool for the assessment of loosening of pegged glenoid components than did fluoroscopically guided conventional radiography. Further improvement in implant design and fixation technique appears to be necessary for long-term success of cemented glenoid components.
authors.affiliation: Department of Orthopaedic Surgery, University of Zurich, Balgrist, Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Yian
authors.forename: Clément M L
authors.initials: CM
authors.lastname: Werner
authors.forename: Richard W
authors.initials: RW
authors.lastname: Nyffeler
authors.forename: Christian W
authors.initials: CW
authors.lastname: Pfirrmann
authors.forename: Arun
authors.initials: A
authors.lastname: Ramappa
authors.forename: Atul
authors.initials: A
authors.lastname: Sukthankar
authors.forename: Christian
authors.initials: C
authors.lastname: Gerber
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement; D001843:Bone Cements; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011095:Polyethylenes; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012015:Reference Standards; D015203:Reproducibility of Results; D012785:Shoulder Joint / Q000000981:diagnostic imaging*; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000592:standards; D016896:Treatment Outcome
chemical_list: D001843:Bone Cements; D011095:Polyethylenes