Radiographic evaluation of osseointegration and loosening of titanium implants in the MCP and PIP joints 1 ☆,

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Abstract

Purpose

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.

Section snippets

Patients

All radiographs from all patients (N = 90) consecutively operated with MCP and PIP joint replacements during a period of 7 years and 3 months at the departments of hand surgery in Göteborg and Malmö were analyzed. One patient was lost to follow-up study and thus was excluded from the study, and 1 joint was excluded because of poor quality of radiographs. Three patients had follow-up periods shorter than 1 year and were thus excluded. The study group consisted of 478 titanium fixtures (239

Results

The radiographic scoring showed osseointegration (score, 0 to 2) in 450 fixtures (Table 1), corresponding to a 94% osseointegration rate. In 28 fixtures complete loosening (score, 3) was found, corresponding to a 6% loosening rate (Table 1). Distal fixtures showed a higher loosening rate (18 fixtures) compared with the proximal fixtures (10 fixtures). In the MCP joints there was a loosening rate of 5.7% (with 6 loose fixtures proximally and 18 distally) compared with 7.4% in the PIP joints

Discussion

In hand surgery loosening of endoprostheses is not a commonly discussed problem. One reason is that most implants in small joint arthroplasty use silicon as the implant material, which is fixated by encapsulation by soft tissues rather than bony fixation and therefore, by definition, the implants are radiographically loose.14 Another reason might be that the loads on small joint implants in the hand are considerably less than on implants in the lower extremity, producing fewer clinical symptoms

References (22)

  • T. Albrektsson et al.

    Osseointegration of bone implants. A review of an alternative mode of fixation

    Acta Orthop Scand

    (1987)

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    ☆

    This study was supported by grants from the Göteborg Medical Society, the University of Göteborg and the Capio Research Foundation.

    1

    No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

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    Copyright © 2004 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.