title: The relationship between scapular notching and reverse shoulder arthroplasty prosthesis design.
abstract: BACKGROUND
  Inferior scapular notching is a common radiographic complication of reverse shoulder arthroplasty. The purpose of this study is to determine the impact of prosthesis design on the incidence and severity of notching.
  
  
  METHODS
  Eighty-eight patients (mean age, 72 years) who underwent reverse shoulder arthroplasty with a minimum of 12 months' follow-up (mean, 31 months) were retrospectively reviewed. Patients were grouped based on prosthesis design: Tornier (Stafford, TX, USA) (45%), Zimmer (Warsaw, IN, USA) with a nonretentive liner (35%), and Zimmer with a retentive liner (19%). Notching on final radiographs was graded by use of the Sirveaux classification system and a novel classification system.
  
  
  RESULTS
  The incidence of notching was significantly higher with the Tornier prosthesis (92%) compared with the Zimmer prosthesis with nonretentive liners (58%) and retentive liners (71%) (P < .05). The incidence of high-grade notching and the median grade were significantly higher with the Tornier prosthesis compared with the Zimmer prosthesis (P < .05). By use of the novel grading system, there was a higher incidence of notching involving the baseplate with the Tornier prosthesis (68%) compared with the Zimmer prosthesis (33%) (P < .05). The addition of a retentive liner was not associated with greater notching than a nonretentive liner for the Zimmer implant. Diagnosis had no significant influence on notching.
  
  
  CONCLUSIONS
  A higher incidence and severity of notching were observed with the Tornier reverse arthroplasty compared with the Zimmer reverse arthroplasty at short-term follow-up. These findings may be because of the different morphology of the polyethylene component and/or differences in glenosphere offset between the prosthetic systems. In addition to surgical technique, consideration should be given to prosthesis design in mitigating the risk of scapular notching.
authors.affiliation: Department of Orthopaedic Surgery, Lenox Hill Hospital, Park Lenox Orthopaedics, New York, NY, USA.
authors.forename: Marc S
authors.initials: MS
authors.lastname: Kowalsky
authors.forename: Leesa M
authors.initials: LM
authors.lastname: Galatz
authors.forename: Derek S
authors.initials: DS
authors.lastname: Shia
authors.forename: Karen
authors.initials: K
authors.lastname: Steger-May
authors.forename: Jay D
authors.initials: JD
authors.lastname: Keener
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies; D012540:Scapula / Q000000981:diagnostic imaging / Q000601:surgery*; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome