title: A new classification of glenoid bone loss to help plan the implantation of a glenoid component before revision arthroplasty of the shoulder.
abstract: OBJECTIVE
  Glenoid bone loss can be a challenging problem when revising a shoulder arthroplasty. Precise pre-operative planning based on plain radiographs or CT scans is essential. We have investigated a new radiological classification system to describe the degree of medialisation of the bony glenoid and that will indicate the amount of bone potentially available for supporting a glenoid component. It depends on the relationship between the most medial part of the articular surface of the glenoid with the base of the coracoid process and the spinoglenoid notch: it classifies the degree of bone loss into three types. It also attempts to predict the type of glenoid reconstruction that may be possible (impaction bone grafting, structural grafting or simple non-augmented arthroplasty) and gives guidance about whether a pre-operative CT scan is indicated.
  
  
  METHODS
  Inter-method reliability between plain radiographs and CT scans was assessed retrospectively by three independent observers using data from 39 randomly selected patients. Inter-observer reliability and test-retest reliability was tested on the same cohort using Cohen's kappa statistics. Correlation of the type of glenoid with the Constant score and its pain component was analysed using the Kruskal-Wallis method on data from 128 patients. Anatomical studies of the scapula were reviewed to explain the findings.
  
  
  RESULTS
  Excellent inter-method reliability, inter-observer and test-retest reliability were seen. The system did not correlate with the Constant score, but correlated well with its pain component.
  
  
  CONCLUSIONS
  Our system of classification is a helpful guide to the degree of glenoid bone loss when embarking on revision shoulder arthroplasty.
authors.affiliation: Semmelweis University Budapest, 27 Karolina St. Budapest 1113, Hungary.
authors.forename: G
authors.initials: G
authors.lastname: Kocsis
authors.affiliation: Sheffield Teaching Hospitals NHS Trust, Herries Road, Sheffield S5 7AU, UK.
authors.forename: D S
authors.initials: DS
authors.lastname: Thyagarajan
authors.affiliation: Nottingham University Hospitals NHS Trust, Hucknall Road, NG5 1PB, UK.
authors.forename: K J
authors.initials: KJ
authors.lastname: Fairbairn
authors.affiliation: University of Nottingham, C Floor, West Block, Queen's Medical Centre, Nottingham NG7 2UH, UK.
authors.forename: W A
authors.initials: WA
authors.lastname: Wallace
mesh_terms: D019643:Arthroplasty, Replacement / Q000379:methods*; D016025:Bone Transplantation / Q000379:methods; D061165:Glenoid Cavity / Q000000981:diagnostic imaging*; D006801:Humans; D015588:Observer Variation; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D011300:Preoperative Care / Q000379:methods; D012086:Reoperation / Q000379:methods; D015203:Reproducibility of Results; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed
keywords: bone grafting; bone loss; classification; glenoid; loosening; osteolysis; revision; score; shoulder arthroplasty