Femoral strain changes after total hip arthroplasty--patient-specific finite element analyses 12 years after operation.

Periprosthetic stress-shielding after total hip arthroplasty (THA) is a well-known phenomenon. Many authors have used the finite element (FE) method to show the effects of THA on animal or human femora. In most cases they have performed cadaver experiments. The current project is a FE analysis based on a retrospective computerized tomography (CT) in vivo data set of 11 patients 12 years after THA. In order to control the analysis, a computationally created stem was implanted at the femur model of the not operated contralateral side. In comparison to the not operated side, there was a significant reduction of the strain energy density (SED) values in all regions of interest (ROI) with the greatest effect near the distal tip of the stem. Only zone 1 showed no clear trend which may be due to load application at the greater trochanter causing local strain peaks. The median SED values changed by -31.65% (ROI 1), -25.64% (ROI 2), -30.82% (ROI 3), -12.35% (ROI 4), -40.10% (ROI 5), -30.37% (ROI 6) and -43.38% (ROI 7). As far as we are aware, the current combination of in vivo CT density data with FE strain analyses after THA is based on the largest number of patients and the longest follow-up period. This combination enables analysis and prediction of the influence of implantation upon bone and can be compared with of remodelling theories. The assessment of mechanical strain data during a follow-up trial could be a new approach for analyzing different hip stems in clinical biomechanics.

[1]  S. Cowin,et al.  On the dependence of the elasticity and strength of cancellous bone on apparent density. , 1988, Journal of biomechanics.

[2]  G. Bergmann,et al.  Hip joint loading during walking and running, measured in two patients. , 1993, Journal of biomechanics.

[3]  D P Fyhrie,et al.  Trabecular bone density and loading history: regulation of connective tissue biology by mechanical energy. , 1987, Journal of biomechanics.

[4]  W. Hayes,et al.  The compressive behavior of bone as a two-phase porous structure. , 1977, The Journal of bone and joint surgery. American volume.

[5]  S. Cowin,et al.  Bone remodeling I: theory of adaptive elasticity , 1976 .

[6]  R. B. Ashman,et al.  Relations of mechanical properties to density and CT numbers in human bone. , 1995, Medical engineering & physics.

[7]  W H Harris,et al.  Proximal strain distribution in the loaded femur. An in vitro comparison of the distributions in the intact femur and after insertion of different hip-replacement femoral components. , 1978, The Journal of bone and joint surgery. American volume.

[8]  D R Sumner,et al.  Sensitivity of periprosthetic stress-shielding to load and the bone density-modulus relationship in subject-specific finite element models. , 2000, Journal of biomechanics.

[9]  Jan Schmitt,et al.  Validation data for periprosthetic bone remodelling theories. , 2002, Journal of biomechanics.

[10]  M Lengsfeld,et al.  [Fully automated generation of hip prosthesis voxel models of the femur for finite element analysis. Comparison of direct and subsequent prosthesis implantation]. , 1997, Biomedizinische Technik. Biomedical engineering.

[11]  C. Engh,et al.  The case for porous-coated hip implants. The femoral side. , 1990, Clinical orthopaedics and related research.

[12]  F. Mayer,et al.  Precision of the measurements of periprosthetic bone mineral density in hips with a custom-made femoral stem. , 2000, The Journal of bone and joint surgery. British volume.

[13]  M. Lukoschek,et al.  Periprosthetic Mineralization Around Cementless Total Hip Endoprosthesis: Longitudinal Study and Cross-Sectional Study on Titanium Threaded Acetabular Cup and Cementless Spotorno Stem with DEXA , 1998, Calcified Tissue International.

[14]  H. Grootenboer,et al.  Adaptive bone-remodeling theory applied to prosthetic-design analysis. , 1987, Journal of biomechanics.

[15]  J. Jurvelin,et al.  Bone density at the proximal femur after total hip arthroplasty. , 1998, Clinical orthopaedics and related research.

[16]  A. Amis,et al.  Correlation between pre-operative periprosthetic bone density and post-operative bone loss in THA can be explained by strain-adaptive remodelling. , 1999, Journal of biomechanics.

[17]  T. Keller,et al.  Young's modulus, bending strength, and tissue physical properties of human compact bone , 1990, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[18]  H. Frost.  The Laws of Bone Structure , 1965 .

[19]  C J Sutherland,et al.  Artifacts and thresholding in X-ray CT of a cortical bone and titanium composite. , 1996, Journal of computer assisted tomography.

[20]  Jan Schmitt,et al.  Die Anwendung voxelorientierter Femurmodelle zur Spannungsanalyse Generierung, Berechnung und Validierung CT-basierter FEM-Modelle - The Use of Voxel-Oriented Femur Models in Stress Analysis Preprocessing, calculation and validation of CT-based finite element models , 1995 .

[21]  C. Engh,et al.  Porous-coated hip replacement. The factors governing bone ingrowth, stress shielding, and clinical results. , 1987, The Journal of bone and joint surgery. British volume.

[22]  Friedrich Pauwels,et al.  Biomechanics of the Locomotor Apparatus , 1980 .

[23]  L Cristofolini,et al.  A comparative study on different methods of automatic mesh generation of human femurs. , 1998, Medical engineering & physics.

[24]  R. Huiskes,et al.  Hip-joint and abductor-muscle forces adequately represent in vivo loading of a cemented total hip reconstruction. , 2001, Journal of biomechanics.

[25]  D R Sumner,et al.  Adaptive bone remodeling around bonded noncemented total hip arthroplasty: A comparison between animal experiments and computer simulation , 1993, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[26]  R. Huiskes,et al.  Preclinical testing of total hip stems. The effects of coating placement. , 1995, Clinical orthopaedics and related research.

[27]  M Viceconti,et al.  Analysis of titanium induced CT artifacts in the development of biomechanical finite element models. , 1998, Medical engineering & physics.

[28]  E. Schneider,et al.  Estimation of mechanical properties of cortical bone by computed tomography , 1991, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[29]  E. Schneider,et al.  Influence of muscle forces on femoral strain distribution. , 1998, Journal of biomechanics.

[30]  M Lengsfeld,et al.  Comparison of geometry-based and CT voxel-based finite element modelling and experimental validation. , 1998, Medical engineering & physics.

[31]  R P Franke,et al.  Sensitivity of femoral strain pattern analyses to resultant and muscle forces at the hip joint. , 1996, Medical engineering & physics.

[32]  J. Galante,et al.  ESB Research Award 1992. The mechanism of bone remodeling and resorption around press-fitted THA stems. , 1993, Journal of biomechanics.

[33]  S. Goldstein,et al.  Evaluation of orthogonal mechanical properties and density of human trabecular bone from the major metaphyseal regions with materials testing and computed tomography , 1991, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[34]  W H Harris,et al.  A quantitative evaluation of periprosthetic bone-remodeling after cementless total hip arthroplasty. , 1992, The Journal of bone and joint surgery. American volume.