title: Accuracy of glenoid component placement in total shoulder arthroplasty and its effect on clinical and radiological outcome in a retrospective, longitudinal, monocentric open study.
abstract: BACKGROUND
  The success of Total Shoulder Arthroplasty (TSA) is believed to depend on the restoration of the natural anatomy of the joint and a key development has been the introduction of modular humeral components to more accurately restore the patient's anatomy. However, there are no peer-reviewed studies that have reported the degree of glenoid component mal-position achieved in clinical practice and the clinical outcome of such mal-position. The main purpose of this study was to assess the accuracy of glenoid implant positioning during TSA and to relate it to the radiological (occurrence of radiolucent lines and osteolysis on CT) and clinical outcomes.
  
  
  METHODS
  68 TSAs were assessed with a mean follow-up of 38+/-27 months. The clinical evaluation consisted of measuring the mobility as well as of the Constant Score. The radiological evaluation was performed on CT-scans in which metal artefacts had been eliminated. From the CT-scans radiolucent lines and osteolysis were assessed. The positions of the glenoid and humeral components were also measured from the CT scans.
  
  
  RESULTS
  Four position glenoid component parameters were calculated The posterior version (6°±12°; mean ± SD), the superior tilt (12°±17°), the rotation of the implant relative to the scapular plane (3°±14°) and the off-set distance of the centre of the glenoid implant from the scapular plane (6±4 mm). An inferiorly inclined implant was found to be associated with higher levels of radiolucent lines while retroversion and non-neutral rotation were associated with a reduced range of motion.
  
  
  CONCLUSIONS
  this study demonstrates that glenoid implants of anatomic TSA are poorly positioned and that this malposition has a direct effect on the clinical and radiological outcome. Thus, further developments in glenoid implantation techniques are required to enable the surgeon to achieve a desired implant position and outcome.
authors.affiliation: Department of Orthopaedic Surgery, APHP, European Hospital Georges Pompidou, Paris, France ; Mechanical Engineering, Imperial College, London, England.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Gregory
authors.forename: Andrew
authors.initials: A
authors.lastname: Sankey
authors.forename: Bernard
authors.initials: B
authors.lastname: Augereau
authors.forename: Eric
authors.initials: E
authors.lastname: Vandenbussche
authors.forename: Andrew
authors.initials: A
authors.lastname: Amis
authors.forename: Roger
authors.initials: R
authors.lastname: Emery
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hansen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012540:Scapula / Q000000981:diagnostic imaging / Q000601:surgery*; D012782:Shoulder / Q000000981:diagnostic imaging / Q000601:surgery*; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome