DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL

DJ Simpson; H Gray; CAF Dodd; DJ Beard; AJ Price; DW Murray; HS Gill

doi:10.1302/0301-620X.91BSUPP_III.0910414b

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DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL

DJ Simpson
H Gray
CAF Dodd
DJ Beard
AJ Price
DW Murray
HS Gill

DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL

Simpson D, Gray H, Dodd C, et al. DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL. Orthop Procs. 2009;91-B(SUPP_III):414-414. doi:10.1302/0301-620X.91BSUPP_III.0910414b

Simpson, DJ, et al. “DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL.” Orthopaedic Proceedings, vol. 91-B, no. SUPP_III, 2009, pp. 414-414., https://doi.org/10.1302/0301-620X.91BSUPP_III.0910414b

Simpson, D., Gray, H., Dodd, C., Beard, D., Price, A., Murray, D., & Gill, H. (2009). DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL. Orthopaedic Proceedings, 91-B(SUPP_III), 414-414. https://doi.org/10.1302/0301-620X.91BSUPP_III.0910414b

Simpson, D., Gray, H., Dodd, C., Beard, D., Price, A., Murray, D. et al. (2009) “DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL.” Orthopaedic Proceedings, 91-B(SUPP_III), pp. 414-414. Available at: https://doi.org/10.1302/0301-620X.91BSUPP_III.0910414b

Simpson, DJ, H Gray, CAF Dodd, DJ Beard, AJ Price, DW Murray, and HS Gill. “DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL.” Orthopaedic Proceedings 91-B, no. SUPP_III (2009): 414-414. https://doi.org/10.1302/0301-620X.91BSUPP_III.0910414b

Simpson D, Gray H, Dodd C, Beard D, Price A, Murray D, et al. DEVELOPING AND VALIDATING A UNICOMPARTMENTAL KNEE REPLACEMENT MODEL. Orthop Procs. 2009 Sep 1;91-B(SUPP_III):414-414. https://doi.org/10.1302/0301-620X.91BSUPP_III.0910414b

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Abstract

Statement of purpose: Finite element (FE) models of bone can be used to evaluate new and modified knee replacements. Validation of FE models is seldom used, and the quantification of modelling parameters has a considerable effect on the results obtained. The aim of this study is to develop a FE model of a cadaveric tibia and validate it against a comprehensive set of experiments.

Summary of Methods: Seventeen tri-axial rosettes were attached to a cleaned, fresh frozen cadaveric human tibia and the tibia was subjected to 13 loading conditions. Deflection and strain data were used for comparison with the FE model. A geometric model was created on the basis of computed tomography (CT) scans. The CT data was used to map 600 orthotropic material properties to the tibia. All experiments were simulated on the FE model. Measured principal strains were compared to their corresponding FE values using regression analysis. The validated tibia model was reduced in size (75mm to the proximal) and then re-modelled to represent only the proximal tibia. This re-modelled tibia was validated against the reduced size FE model. Virtual surgery was performed on the validated proximal model to implant a UKR.

Summary of Results: For the whole tibia model, the regression line for all axial loads combined had a slope of 0.999, an intercept of −6.24 micro-strain, and an R2 value of 0.962. The root mean square error as a percentage was 5%. For the proximal tibia model, correlation coefficients of 0.989 and 0.976 were obtained for the maximum and minimum principal strains respectively.

Statement of Conclusions: An FE model of an implanted proximal tibia has been validated against experimental data. This model is able to accurately predict the deflection and stresses in a replaced knee joint to obtain clinically relevant information. This will provide a virtual model of unicompartmental arthroplasty, where variables such as fixation method and bearing mechanics can be assessed.

Correspondence should be addressed to Mr T Wilton, c/o BOA, BASK at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE, England.