Tribocorrosion in shoulder arthroplasty humeral component retrievals.

Background: Tribocorrosion at the modular taper connections of total hip implants has been associated with trunnionosis and adverse local tissue reactions. Modularity is also widely used in shoulder arthroplasty implants, but little information exists about the potential for tribocorrosion. This study hypothesized that there would be mild or no tribocorrosion in a series of retrieved shoulder implants.

Methods: A total of 28 implants with a mean implantation time of 6.2 ± 6.0 years were evaluated using a validated damage scoring method. Implant tapers on the head and stem were divided into upper (deepest) and lower zones and independently scored for fretting and corrosion damage from 1 (none) to 4 (severe).

Results: Corrosion was present on 32% of heads and 38% of stems, whereas fretting was present on 36% of heads and 46% of stems. There was significantly greater (P = .02) corrosion in the lower zone of the retrieved stems (1.4 ± 0.5) than there was in the upper zone (1.1 ± 0.3). Correlation between the head and stem corrosion for lower zone was moderate (r = 0.41; P = .04).

Discussion: Tribocorrosion was present on the heads and stems of some of the retrieved shoulder implants examined in this study. The incidence of tribocorrosion in shoulder implants was lower than in reported cases of retrieved hip implants. The greatest damage was in the lower zone of the taper, where the connection may be exposed to the surrounding joint fluid. It remains to be seen whether this leads to any clinical presentation of trunnionosis.