title: Influence of prosthetic design on radiocapitellar concavity-compression stability.
abstract: BACKGROUND
  Radial head prostheses are available with multiple geometric properties. The effect of design features on radiocapitellar stability has not been investigated.
  
  
  OBJECTIVE
  The shape (depth and radius of curvature) of the articulating dish of a radial head prosthesis affects radiocapitellar stability.
  
  
  METHODS
  Radiocapitellar stability due to concavity-compression was evaluated in 8 fresh frozen elbows before and after radial head replacement with 2 different designs of radial head implants (RH 1 and RH 2). Both functioned as monopolar implants. Peak forces resisting subluxation and force-displacement characteristics were compared between the 2 and to the native radial head.
  
  
  RESULTS
  Radial head design significantly affected radiocapitellar stability. RH 1, which had a deeper dish than RH 2, required significantly higher peak forces to subluxate the radiocapitellar joint. The peak subluxation forces and the slopes of the force-displacement curves were not significantly different from the native radial head for RH 1, but they were for RH 2.
  
  
  CONCLUSIONS
  The shape of the articular dish (depth, radius of curvature) of a monopolar radial head implant affects its contribution to radiocapitellar stability. An implant that mimics normal anatomy is more effective than a shallow radial head implant with a radius of curvature that is longer than normal.
authors.affiliation: Department of Orthopedics, Faculty of Medicine, HRH Princess Maha Chakri Sirindhorn Medical Center, Srinakhrinwirot University, Bangkok, Thailand.
authors.forename: Cholawish
authors.initials: C
authors.lastname: Chanlalit
authors.forename: Dave R
authors.initials: DR
authors.lastname: Shukla
authors.forename: James S
authors.initials: JS
authors.lastname: Fitzsimmons
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
authors.forename: Shawn W
authors.initials: SW
authors.lastname: O'Driscoll
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D004551:Elbow Joint / Q000601:surgery*; D005260:Female; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011884:Radius