title: Radiographic evaluation of osseointegration and loosening of titanium implants in the MCP and PIP joints.
abstract: OBJECTIVE
  Good to excellent clinical results have been shown in the initial studies on osseointegrated metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joint implants that consist of a flexible silicone spacer connected to osseointegrated titanium fixtures. A high fracture rate of the silicone spacer, however, has been reported, diminishing the value of this implant system. The purpose of this study was to evaluate the osseointegration of the titanium fixture itself in a large study group and compare patients with rheumatoid arthritis with those with osteoarthrosis as a base for further development of the implant concept.
  
  
  METHODS
  Two hundred thirty-nine implants (27 PIP, 212 MCP) in 86 patients were retrospectively evaluated radiographically. Two hundred implants were in patients with rheumatoid arthritis. Radiographic evaluation included measuring the length and width of resorption zones around the titanium fixtures. A scoring system was used that grouped observations in 4 groups, from 0 (little or no change) to 3 (loosening). Status of the silicone spacer was also noted.
  
  
  RESULTS
  At follow-up evaluation an average of 41 months (range, 12-103 months) after surgery, complete osseointegration was found in 450 of 478 fixtures (94%). Loosening was found in 10 proximal and 18 distal fixtures. The proximal fixtures showed loosening mainly during the first 3 years after surgery and the distal fixtures also had loosening. In the 31 MCP joint implants that were evaluated for more than 5 years, the osseointegration rate was 97%.
  
  
  CONCLUSIONS
  Implant stem fixation with osseointegrated titanium fixtures is a valuable method that works well in rheumatoid arthritis patients. Further development will focus on a more durable constrained joint mechanism.
authors.affiliation: Department of Hand Surgery, Sahlgrenska University Hospital, Göteborg, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Möller
authors.forename: Mats
authors.initials: M
authors.lastname: Geijer
authors.forename: Christer
authors.initials: C
authors.lastname: Sollerman
authors.forename: Göran
authors.initials: G
authors.lastname: Lundborg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000601:surgery; D001178:Arthroplasty; D019544:Equipment Failure Analysis; D005260:Female; D005384:Finger Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D010003:Osteoarthritis / Q000601:surgery; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies; D012826:Silicone Elastomers; D014025:Titanium
chemical_list: D012826:Silicone Elastomers; D014025:Titanium