Properties of the tibial component regarding impact load.
Load transmission through knee prostheses was examined to clarify how the tibial component behaves under dynamic loading conditions. We did Genesis II total knee arthroplasty using sawbones and measured impact load transmission ratios using the split-Hopkinson pressure bar technique. We also measured the polyethylene strain when an impact load was applied using a strain gauge bonded to the anterior surface of the polyethylene. The impact load transmission ratios of metal-backed and all-polyethylene tibial components were less than 4%. Greater load transmission was observed with metal-backed components, which suggests that some of the applied dynamic load is transferred directly to the tibial cortical bone. Increasing polyethylene thickness decreased impact load transmission ratios in both components, which might lower the cancellous bone stresses beneath tibial implants. Greater strain in the tibial component was observed in all-polyethylene components. Increased polyethylene thickness did not significantly decrease the polyethylene strain, probably because of the nonlinear elastic behavior of the polyethylene material. The distant positioning of the strain gauge may, however, have prevented the detection of local contact strains. Recent clinical studies did not confirm our theoretical predictions, suggesting that other factors contribute more significantly to the clinical outcome in current total knee arthroplasty.
Yoshino
Kazunori
K
Division of Orthopedic Surgery, Department of Regenerative and Transplant Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
Koga
Yoshio
Y
Segawa
Hiroyuki
H
Ueno
Yuichi
Y
Tanabe
Yuji
Y
Endo
Naoto
N
Omori
Go
G
D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D007720:Knee Prosthesis; D008422:Materials Testing; D020959:Polyethylene; D011474:Prosthesis Design; D013977:Tibia / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*
D020959:Polyethylene