Six dogs had a total hip arthroplasty during which the femoral component
was coated with methacrylate and inserted in the femoral canal, after the
canal had been reamed to a larger diameter than that of the femoral stem
(including the coating). Thus, the implant was loose and motion was present
between it and the femur in each animal. Five dogs had a revision to a
prosthesis with a porous polysulfone-coated stem. This prosthesis was not
cemented in place. One dog was killed before the revision for the purpose
of histological examination. Although bone was present in the porous
surface of all five stems at the revision, the amount was scant in three.
CLINICAL RELEVANCE: A model is described for the study of cemented
hip-replacement prostheses that have failed. Although variable amounts of
ingrowth of bone were observed after the revision to the porous-coated
prostheses without bone cement, further study is needed to determine
whether adequate ingrowth of bone occurs in this model.