The dog as a preclinical model to evaluate interface morphology and micro-motion in cemented total knee replacement.
OBJECTIVE
This study investigated cemented fixation of the tibial component from a canine total knee replacement preclinical model. The objective was to determine the local morphology at the material interfaces (implant, cement, bone) and the local relative micro- motion due to functional loading following in vivo service.


METHODS
Five skeletally mature research dogs underwent unilateral total knee replacement using a cemented implant system with a polyethylene (PE) monobloc tibial component. Use of the implanted limb was assessed by pressure-sensitive walkway analysis. At 60 weeks post-surgery, the animals were euthanatized and the tibia sectioned en bloc in the sagittal plane to create medial and lateral specimens. High resolution imaging was used to quantify the morphology under the tray and along the keel. Specimens were loaded to 50% body weight and micro- motions at the PE-cement and cement-bone interfaces were quantified.


RESULTS
There was significantly (p = 0.002) more cement-bone apposition and interdigitation along the central keel compared to the regions under the tray. Cavitary defects were associated with the perimeters of the implant (60 ± 25%). Interdigitation fraction was negatively correlated with cavitary defect fraction, cement crack fraction, and total micro-motion.


CONCLUSIONS
Achieving good interdigitation of cement into subchondral bone beneath the tibial tray is associated with improved interface morphology and reduced micro-motion; features that could result in a reduced incidence of aseptic loosening. Multiple drill holes distributed over the cut tibial surface and adequate pressurization of the cement into the subchondral bone should improve fixation and reduce interface micromotion and cavitary defects.
State University of New York, Upstate Medical University, Department of Orthopedic Surgery, 3216 IHP, 750 East Adams Street, Syracuse, New York 13210, United States. mannk@upstate.edu
K A
KA
Mann
M A
MA
Miller
M
M
Khorasani
K L
KL
Townsend
M J
MJ
Allen
D000818:Animals; D019645:Arthroplasty, Replacement, Knee / Q000662:veterinary*; D001843:Bone Cements; D004195:Disease Models, Animal; D004285:Dogs / Q000601:surgery*; D008297:Male; D009038:Motion; D011475:Prosthesis Failure; D013977:Tibia / Q000473:pathology
D001843:Bone Cements