Strain patterns induced by press-fitting and by an external load in hip arthroplasty: A photoelastic coating study on bone models

The success of prostheses is highly dependent upon load transfer and bone stresses. Reflection photoelasticity is a viable technique for measuring stress patterns in vitro. However, when a cementless stem is tested, the resultant stresses under load are the sum of the implantation stresses and of those induced by load application. Separating these two components is a critical issue that so far has not been thoroughly solved using photoelasticity. Implantation strains and strain under load were measured separately by a suitable procedure: the photoelastic coating was applied to the femur after stem press-fitting. Thus, when an external load is applied (e.g. to simulate a physiological activity), the fringe patterns indicate the effect of the external load alone. Implantation strains are measured independently, after load removal; the stem is extracted and stresses are released, causing a new fringe pattern. The method was used to investigate the stress pattern caused by press-fitting of two cementless hip stems and that caused by a load applied to the implanted femora. Different isochromatic and isoclinic patterns were observed for the strain distribution caused by load application and by press-fitting for two stem designs. Differences in press-fit pattern and load transfer were successfully detected between the two designs.

[1]  J. Avril,et al.  Encyclopedie Vishay d'analyse des contraintes , 1974 .

[2]  Tung-Wu Lu,et al.  Muscular Activity and the Biomechanics of the Hip , 1996 .

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

[4]  W. Hayes,et al.  Cross-sectional geometry of Pecos Pueblo femora and tibiae--a biomechanical investigation: I. Method and general patterns of variation. , 1983, American journal of physical anthropology.

[5]  F. Guilak,et al.  Effects of coronally slotted femoral prostheses on cortical bone strain. , 1997, The Journal of arthroplasty.

[6]  Michael A. Sutton,et al.  Towards the standardization of in vitro load transfer investigations of hip prostheses , 1999 .

[7]  John R. Tyrer,et al.  Three-dimensional human femoral strain analysis using ESPI , 1995 .

[8]  L Cristofolini,et al.  Methods for quantitative analysis of the primary stability in uncemented hip prostheses. , 1999, Artificial organs.

[9]  P S Walker,et al.  Effect of press-fit femoral stems on strains in the femur. A photoelastic coating study. , 1990, The Journal of arthroplasty.

[10]  Rita M. Patterson,et al.  Femoral surface strain in intact composite femurs: a custom computer analysis of the photoelastic coating technique , 2000, IEEE Transactions on Biomedical Engineering.

[11]  W. Maloney,et al.  Biomechanical and histologic investigation of cemented total hip arthroplasties. A study of autopsy-retrieved femurs after in vivo cycling. , 1989, Clinical orthopaedics and related research.

[12]  G. Bergmann,et al.  Hip contact forces and gait patterns from routine activities. , 2001, Journal of biomechanics.

[13]  W. Mittelmeier,et al.  The Difference in Loading Pattern of Femoral Neck Endoprostheses and Cementless Hip Stems-a Photostress Analysis , 2001 .

[14]  P S Walker,et al.  A comparison of cortical strain after cemented and press‐fit proximal and distal femoral replacement , 1992, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[15]  L Cristofolini,et al.  Mechanical validation of whole bone composite femur models. , 1996, Journal of biomechanics.

[16]  Marco Viceconti,et al.  Comments on "Femoral surface strain in intact composite femurs: A custom computer analysis of the photoelastic coating technique" [with reply] , 2001, IEEE Trans. Biomed. Eng..

[17]  F. Zandman,et al.  Reinforcing effect of birefringent coatings , 1962 .

[18]  Angelo Cappello,et al.  Experimental errors in the application of photoelastic coatings on human femurs with uncemented hip stems , 1994 .

[19]  P S Walker,et al.  Design and fabrication of cementless hip stems. , 1988, Clinical orthopaedics and related research.

[20]  L Cristofolini,et al.  A critical analysis of stress shielding evaluation of hip prostheses. , 1997, Critical reviews in biomedical engineering.

[21]  Rita M. Patterson,et al.  Authors’ Reply , 2001, IEEE Trans. Biomed. Eng..

[22]  F. Guilak,et al.  The effect of hip stem material modulus on surface strain in human femora. , 1998, Journal of biomechanics.

[23]  J B Finlay,et al.  In vitro analysis of proximal femoral strains using PCA femoral implants and a hip-abductor muscle simulator. , 1989, The Journal of arthroplasty.