title: Effect of baseplate size on primary glenoid stability and impingement-free range of motion in reverse shoulder arthroplasty.
abstract: BACKGROUND
  Use of a baseplate with a smaller diameter in reverse shoulder arthroplasty is increasing, especially in patients with a small glenoid or glenoid wear. However, the effect of a smaller baseplate on stability of the glenoid component has not been evaluated. Thus, the purpose of this study was to determine whether a smaller baseplate (25 mm) is beneficial to the initial stability of the glenoid component compared to that with a baseplate of a commonly used size (29 mm).
  
  
  METHODS
  Micromotion of glenoid components attached to 14 scapulae of fresh-frozen cadavers was measured and compared between 25- and 29-mm baseplates in biomechanical testing. Impingement-free range of motion in abduction, adduction, internal rotation, and external rotation was evaluated by using a simulated computer model constructed based on the same fresh-frozen cadavers used in biomechanical testing.
  
  
  RESULTS
  Micromotion at the inferior third of the glenoid-glenosphere interface was higher in the 29-mm baseplate group than in the 25-mm baseplate group during both 0.7- and 1-body weight cyclic loading in biomechanical testing. Adduction deficit was smaller, and total impingement-free range of motion from abduction to adduction and rotation were greater in the 25-mm baseplate group than in the 29-mm baseplate group in the simulated computer model.
  
  
  CONCLUSIONS
  Use of a baseplate with a smaller diameter (25 mm) in reverse shoulder arthroplasty is suitable for improving the primary stability of the glenoid component. With a smaller baseplate, impingement-free range of motion is optimized in a smaller glenoid.
authors.forename: Soo-Won
authors.initials: SW
authors.lastname: Chae
authors.affiliation: Department of Orthopaedic Surgery, Hallym University, Kangnam Sacred Heart Hospital, Seoul, South Korea. singsingkr@yahoo.co.kr.
authors.forename: Soung-Yon
authors.initials: SY
authors.lastname: Kim
authors.forename: Haea
authors.initials: H
authors.lastname: Lee
authors.forename: Joung-Ro
authors.initials: JR
authors.lastname: Yon
authors.forename: Juneyoung
authors.initials: J
authors.lastname: Lee
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Han
mesh_terms: D000368:Aged; D019643:Arthroplasty, Replacement / Q000295:instrumentation*; D005260:Female; D061165:Glenoid Cavity / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D007595:Joint Prosthesis; D008875:Middle Aged; D011474:Prosthesis Design; D016059:Range of Motion, Articular / Q000502:physiology*; D012782:Shoulder / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome