title: Do the radial head prosthesis components fit with the anatomical structures of the proximal radioulnar joint?
abstract: OBJECTIVE
  The fitting accuracy of radial head components has been investigated in the capitulo-radial joint, and reduced contact after prosthetic replacement of the radial head has been observed. The kinematics of the proximal radioulnar joint (PRUJ) are affected by radial head arthroplasty as well, but have not yet been investigated in this regard.
  
  
  METHODS
  The elbow joints of 60 upper extremities of formalin-fixed body donors were disarticulated to obtain a good view of the PRUJ. Each specimen was mounted on the examining table and radial head position in the native PRUJ was assessed in neutral position, full pronation, and full supination. Measurements were repeated after implantation of mono- and bi-polar prostheses.
  
  
  RESULTS
  Analysis of the distribution of the joint contacts in the compartments showed significant differences after radial head replacement. In comparison to the native joint, after bipolar and monopolar radial head replacement, the physiological shift of the proximal radius was altered.
  
  
  CONCLUSIONS
  The physiological shift of the joint contact of the radial head from anterior to posterior during forearm rotation that was found in the native joint in our cadaver model was not observed after prosthetic replacement. With higher conformity and physiological kinematic of radial head prostheses, possibly lower shear forces and lower contact pressures would be generated.
  
  
  CONCLUSIONS
  The tested radial head prostheses do not replicate the physiological kinematics of the radial head. Further development in the prosthesis design has to be made. The meticulous reconstruction of the annular ligament seems to be of importance to increase joint contact.
authors.affiliation: Centre for Orthopaedic and Trauma Surgery, University Medical Centre, Cologne, Germany, kilian.wegmann@uk-koeln.de.
authors.forename: Kilian
authors.initials: K
authors.lastname: Wegmann
authors.forename: Moritz K
authors.initials: MK
authors.lastname: Hain
authors.forename: Christian
authors.initials: C
authors.lastname: Ries
authors.forename: Wolfram F
authors.initials: WF
authors.lastname: Neiss
authors.forename: Lars P
authors.initials: LP
authors.lastname: Müller
authors.forename: Klaus J
authors.initials: KJ
authors.lastname: Burkhart
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D057929:Arthroplasty, Replacement, Elbow / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D004210:Dissection; D004551:Elbow Joint / Q000033:anatomy & histology / Q000601:surgery*; D058569:Elbow Prosthesis; D005260:Female; D006801:Humans; D008297:Male; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000379:methods*; D011884:Radius / Q000033:anatomy & histology / Q000601:surgery; D016059:Range of Motion, Articular / Q000502:physiology; D012307:Risk Factors; D012680:Sensitivity and Specificity