title: Micromotion of plasma spray versus grit-blasted radial head prosthetic stem surfaces.
abstract: BACKGROUND
  Initial stability of a textured surface prosthetic stem is necessary for bone in-growth. Surfaces currently used for radial head prostheses include titanium plasma spray and grit-blasted titanium.
  
  
  OBJECTIVE
  Plasma spray radial head prosthetic stems are less dependent than grit-blasted stems on a tight press fit. Good initial press-fit stability, with acceptable micro-motion, can be achieved with a greater range of stem sizes using a plasma spray than grit-blasted surface.
  
  
  METHODS
  Paired cadaveric radii were implanted with plasma spray or grit-blasted radial head prosthetic stems. Micromotion at the stem tip was measured under circumstances simulating eccentric loads.
  
  
  RESULTS
  Micromotion in the plasma spray (PS) stems (49 ± 37) μm was not better than that in the grit-blasted (GB) stems (28 ± 10) μm (P = .13). Micromotion of less than 100 μm was measured in all 12 GB stems that were maximum or 1 mm less than maximum size, versus 5/6, and 4/6 PS stems, respectively.
  
  
  CONCLUSIONS
  Micromotion in plasma spray prosthetic radial head stems was not better than that seen in grit-blasted stems, contrary to our initial hypothesis.
  
  
  CONCLUSIONS
  Grit-blasted prosthetic radial head stems confer initial press-fit stability that is as good as, or slightly better than, corresponding plasma spray stems. Acceptable amounts of micromotion can be achieved with 2 grit-blasted stem sizes and probably with 2 plasma spray stem sizes.
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: James S
authors.initials: JS
authors.lastname: Fitzsimmons
authors.forename: Dave R
authors.initials: DR
authors.lastname: Shukla
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
authors.forename: Shawn W
authors.initials: SW
authors.lastname: O'Driscoll
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D057929:Arthroplasty, Replacement, Elbow / Q000295:instrumentation*; D002102:Cadaver; D058569:Elbow Prosthesis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D011884:Radius / Q000601:surgery*; D016059:Range of Motion, Articular / Q000502:physiology*; D013314:Stress, Mechanical; D013499:Surface Properties