Evaluation of metallic personalized hemiarthroplasty: a canine patellofemoral model.
The purpose of this study was to characterize the response of articular cartilage to weight bearing against a metallic personalized hemiarthroplasty prosthesis. Ten dogs each underwent surgery in which an elastomeric replica of the left femoral patellar groove was made. Using this replica, a 0.5-mm-thick prosthesis was cast in Co-Cr alloy and subsequently the surface was polished to a mirror finish which had a center line average roughness value in the range of human hemiarthroplasty implants. A second surgery was performed to resurface the left trochlea with this prosthesis. Five animals were sacrificed at 3 months and 5 at 6 months. Cartilage damage occurred primarily in the distal region of the patella, and was especially evident at 6 months. Mechanical indentation tests conducted on patellar cartilage in a saline bath at 37 degrees C indicated both increased deformation and residual deformation in the affected areas, indicative of degenerative change. Areas of fibrillation with a depletion of proteoglycans were identified histologically. These areas were only superficial at 3 months but became more extensive at 6 months. Rheological analysis of the synovial fluid of tests joints indicated that a decrease in viscosity occurred from 3 to 6 months, an additional indicator of progressive degeneration. This novel implant model showed that even if a metallic hemiarthroplasty implant had an identical geometry as the joint surface being replaced and had a reasonably smooth surface, cartilage degeneration inevitably resulted.
LaBerge
M
M
Department of Bioengineering, Clemson University, South Carolina 29634.
Bobyn
J D
JD
Drouin
G
G
Rivard
C H
CH
D000818:Animals; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000473:pathology / Q000503:physiopathology; D004285:Dogs; D005069:Evaluation Studies as Topic; D005269:Femur / Q000601:surgery; D007595:Joint Prosthesis / Q000009:adverse effects; D008422:Materials Testing; D008670:Metals; D008954:Models, Biological; D010329:Patella / Q000601:surgery; D013582:Synovial Fluid / Q000502:physiology
D008670:Metals