Comparison of the fit and geometry of reconstruction of femoral components of four cemented canine total hip replacement implants.
OBJECTIVE
To compare fit and geometry of reconstruction of femoral components of 4 canine cemented total hip replacement implants and determine which implants are most compatible with current principles of cemented arthroplasty.


METHODS
Paired femurs from 16 adult mixed-breed dogs.


METHODS
Femurs were prepared for femoral stem implantation of either the Bardet, BioMedtrix, Mathys, or Richards II implant. Mediolateral and craniocaudal radiographs were obtained with femoral components in situ. Cross-sectional analysis of implant fit was performed on transected cemented specimens. Computer-aided analyses of digitized images were performed.


RESULTS
The Bardet and Richards II implants reconstructed the original femoral head position significantly better than the other 2 implants. None of the implants allowed neutralization of the implant axis in the sagittal plane or were routinely centralized in the femoral canal. The Bardet implant had the smallest minimum distal tip offset in the sagittal plane. Greatest tip to cortex distance was provided by the Richards II implant in the transverse plane and the Mathys implant in the sagittal plane. The thinnest cement mantle regions for all implants were in the central longitudinal third of the femoral stem.


CONCLUSIONS
The Bardet and BioMedtrix implants had stem design characteristics that were most compatible with principles of cemented stem fixation. None of the implants completely satisfied the theoretically optimal conditions of centralization and neutralization of the femoral stem. Innovative design modifications, therefore, may be needed if these conditions are important to the long-term success of canine total hip replacement.
Schulz
K S
KS
JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis 95616, USA.
Nielsen
C
C
Stover
S M
SM
Kass
P H
PH
D000818:Animals; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000662:veterinary*; D001672:Biocompatible Materials; D004283:Dog Diseases / Q000473:pathology / Q000601:surgery*; D004285:Dogs; D005269:Femur; D006622:Hip Prosthesis / Q000662:veterinary*
D001672:Biocompatible Materials