Synovitis subsequent to total-hip arthroplasty with and without hydroxyapatite coatings: a study in dogs.
OBJECTIVE
To establish whether hydroxyapatite (HA) coatings applied to metal total-hip-replacement components increased synovitis in the coxofemoral joint of dogs. Study Design-An in vivo research trial and histologic study.


METHODS
Twenty-three large, mixed-breed dogs.


METHODS
Arthroplasty components were implanted with HA on neither stem nor cup, or with HA applied to either the femoral component or with both stem and cup having HA applied in 23 dogs. Synovial inflammation was scored 3, 6, and 12 months after surgery. Synovial membrane thickness; polyethylene particulate load; fibrin exudate; membrane edema; mitotic index; giant-cell, mononuclear histiocyte, lymphocyte, and polymorph number; and collagen degeneration were scored and statistical analyses performed.


RESULTS
Operated-side synovial thickness was greatly increased relative to control. Fibrin deposition, intramembranous edema, and collagen degeneration were similar within each time interval among the various component groups. The majority of inflammatory scores among the groups were unchanged. In this 12-month study, the presence of HA coatings appear not to have a marked impact on the development of synovial inflammation.


CONCLUSIONS
HA-coated components do appear to contribute somewhat to the inflammatory load within the periprosthetic environment, but this effect is not marked.


CONCLUSIONS
The major advantage of HA addition to arthroplasty components is enhanced osteoconductivity around metallic surfaces. The slight increase in particulate load seen in the presence of HA coatings may contribute to the development of aseptic loosening of arthroplasty components, but is unlikely to be the major causative factor.
Anderson
G I
GI
Faculties of Dentistry and Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
Orlando
K
K
Waddell
J P
JP
D000818:Animals; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation / Q000662:veterinary*; D001672:Biocompatible Materials / Q000009:adverse effects*; D004283:Dog Diseases / Q000139:chemically induced*; D004285:Dogs / Q000601:surgery*; D017886:Durapatite / Q000009:adverse effects*; D006621:Hip Joint / Q000473:pathology; D011474:Prosthesis Design; D013583:Synovial Membrane / Q000473:pathology; D013585:Synovitis / Q000139:chemically induced / Q000662:veterinary*
D001672:Biocompatible Materials; D017886:Durapatite