title: Clinical and radiographic comparisons of two different radial head implant designs.
abstract: BACKGROUND
  There is little comparative data to guide implant choice for radial head replacements. The purpose of this study was to evaluate the clinical and radiographic results between patients who received a smooth-stemmed bipolar radial head implant and patients who received an in-growth monopolar prosthesis.
  
  
  METHODS
  Twenty-seven patients requiring a metallic radial head implant in the management of acute or chronic elbow trauma were evaluated. Fourteen patients received a smooth-stemmed bipolar prosthesis and 13 patients received a press-fit monopolar prosthesis. Patients returned for follow-up at an average of 33 months (range, 18-57). Outcome assessments included joint motion, elbow stability, grip strength, pain, the Mayo Elbow Performance Index, and the Disability of Arm, Shoulder and Hand questionnaire. Radiographs were reviewed for joint congruence, ectopic bone, periprosthetic osteolysis, degenerative arthritis, and capitellar wear, and selected patients were tested for inflammatory markers and metal ion levels.
  
  
  RESULTS
  The differences between patient groups for elbow flexion and forearm pronation averaged 10° or less. There were no other pertinent differences between groups for standardized patient and examiner-determined outcomes. There was a trend for ectopic bone to develop more commonly around the smooth-stemmed implants, while periprosthetic osteolysis was more pronounced in cases with the press-fit design. Inflammatory markers were normal, and metal ion levels did not exceed values reported for a well-functioning hip arthroplasty.
  
  
  CONCLUSIONS
  Outcomes at short- to mid-term follow-up were similar with either implant design. Loosening of a press-fit prosthesis may lead to extensive osteolysis, but of undetermined clinical consequence.
authors: Department of Orthopaedic Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60612, USA.
authors: John C
authors: JC
authors: Berschback
authors: T Sean
authors: TS
authors: Lynch
authors: David M
authors: DM
authors: Kalainov
authors: Robert W
authors: RW
authors: Wysocki
authors: Bradley R
authors: BR
authors: Merk
authors: Mark S
authors: MS
authors: Cohen
mesh_terms: D000328:Adult; D000368:Aged; D019643:Arthroplasty, Replacement; D015331:Cohort Studies; D004551:Elbow Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011859:Radiography; D011885:Radius Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D016059:Range of Motion, Articular / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology; D016896:Treatment Outcome; D055815:Young Adult; D000092464:Elbow Injuries
keywords: Level III; Radial head arthroplasty; Retrospective Cohort Study; Treatment Study; elbow joint; heterotopic ossification; metal ions; osteolysis; radial head fracture