title: Stable fixation of the ulnar component in the Kudo elbow prosthesis. A radiostereometric (RSA) study of 13 prostheses with 2-year follow-up.
abstract: BACKGROUND
  Concern has been expressed about the large number of radiolucent lines around the ulnar component of the Kudo elbow prosthesis in medium-term follow-up.
  
  
  METHODS
  We studied the metal-backed cemented ulnar component in 13 Kudo elbow prostheses (type 5) using radiostereometric analysis (RSA). All patients had rheumatoid arthritis. There were 2 men and 9 women with a mean age of 55 years. 2 were operated bilaterally. The metal-backed ulnar component was marked with three 0.8 mm tantalum spheres and the proximal ulna with 5 spheres of 0.8 or 1.0 mm diameter. The initial RSA examination was performed during the first week after the operation. Further examinations were done at 4, 12 and 24 months. Conventional radiographs were taken during the first week postoperatively, and at 12 and 24 months.
  
  
  RESULTS
  Translations (medial/lateral, antero/posterior and proximal/distal) were less than 0.5 mm in all but 1 patient who had a maximal translation of 3.4 mm distally. The mean rotations around all three axes were less than 0.4 degrees. The patient who had a translation of 3.4 mm also had varus angulation exceeding 4 degrees. This patient also had progressive circumferential radiolucent lines on conventional radiographs. The Mayo elbow score increased from 40 (25-65) before surgery to 92 (45-100) at 2 years.
  
  
  CONCLUSIONS
  The fixation of the metal-backed ulnar component of the Kudo elbow prosthesis at 2 years is good.
authors.affiliation: Department of Orthopedics, University Hospital, SE-751 85 Uppsala, Sweden. Hans.Rahme@telia.com
authors.forename: Hans
authors.initials: H
authors.lastname: Rahme
authors.forename: Per
authors.initials: P
authors.lastname: Mattsson
authors.forename: Sune
authors.initials: S
authors.lastname: Larsson
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000601:surgery*; D019643:Arthroplasty, Replacement / Q000379:methods; D004551:Elbow Joint / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D016896:Treatment Outcome; D014457:Ulna / Q000601:surgery*