Strains and micromotions of press-fit femoral stem prostheses

Walker, P. S.; Schneeweis, D.; Murphy, S.; Nelson, P.

Affiliations

¹Orthopaedic Biomechanics, Brigham & Womens Hospital, Boston, MA

³Massachusetts Institute of Technology, Cambridge, MA, U.S.A.

Abstract

Average femoral geometry was determined from sections of 25 human femurs. A ‘stem design program’ was used to determine the largest femoral stem that could be introduced into the canal. The stem was fine tuned by observations of fit in Plexiglass models of the 25 femurs. This stem was called the ‘Exact-Fit’. Type 1 stem was formed by grinding the anterior and posterior faces flat. Type 2 stem was formed by additionally grinding the medial and lateral faces flat. Four fresh femurs were used for the experiments. Strain gages were located on the proximal medial area and level with the distal lateral tip. Displacement transducers were mounted proximally to measure stem-bone micromotion. Vertical and anterior-posterior forces were applied to the femoral head and normal strain data obtained. The stems were then inserted in sequence and the strains and micromotions were measured. After the uncemented stems had been tested, a smaller size of ‘exact-fit’ stem was cemented and the tests repeated. The strains with the uncemented stems were closer to normal than with the cemented stems. For example, compressive calcar strains averaged 56% of normal uncemented compared with 30% cemented for the different loadings. The micromotion was higher uncemented, but was still at a low level. The ‘exact-fit’ stem gave less resultant micromotion than the type 1 and type 2 stems. The high variation of the strain results was attributed to variations in stem-bone contact and fit. The study provided information of direct application to press-fit stems in hip replacement surgery.

Links

DOI: 10.1016/0021-9290(87)90035-2

PubMed: 3654667

WoS: A1987J672800004

History

Received: 1985-08-2

Revised: 1986-08-27

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Cited By (17)

Year	Entry
1996	van Rietbergen B. Mechanical Behavior and Adaptation of Trabecular Bone in Relation to Bone Morphology [PhD thesis]. Nijmegen, Netherlands: Catholic University of Nijmegen; 1996.
1991	Weinans HH. Mechanically Induced Bone Adaptations Around Orthopaedic Implants [PhD thesis]. Nijmegen, The Netherlands: Katholieke Universiteit te Nijmegen; 1991.
1990	Huiskes R. The various stress patterns of press-fit, ingrown, and cemented femoral stems. Clin Orthop Relat Res. December 1990;261:27-38.
1993	Van Rietbergen B, Huiskes R, Weinans H, Sumner DR, Turner TM, Galante JO. The mechanism of bone remodeling and resorption around press-fitted THA stems. J Biomech. April–May 1993;26(4-5):369-382.
1993	Bergmann G, Graichen F, Rohlmann A. Hip joint loading during walking and running, measured in two patients. J Biomech. August 1993;26(8):969-990.
1993	Keaveny TM, Bartel DL. Effects of porous coating and collar support on early load transfer for a cementless hip prosthesis. J Biomech. October 1993;26(10):1205-1216.
1994	Keaveny TM, Wachtel EF, Ford CM, Hayes WC. Differences between the tensile and compressive strengths of bovine tibial trabecular bone depend on modulus. J Biomech. 1994;27(9):1137-1146.
1993	Keyak JH, Fourkas MG, Meagher JM, Skinner HB. Validation of an automated method of three-dimensional finite element modelling of bone. J Biomed Eng. November 1993;15(6):505-509.
2004	Gupta S, van der Helm FCT, Sterk JC, van Keulen F, Kaptein BL. Development and experimental validation of a three-dimensional finite element model of the human scapula. Proc Inst Mech Eng Part H-J Eng Med. March 2004;218(3):127-142.
1994	Simmons CA. Optimal Surface Coating Distribution on a Femoral Endoprosthesis [Master's thesis]. Cambridge, MA: Massachusetts Institute of Technology; February 1994.
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2000	Maher SA. Design and Development of a Pre-Clinical Test for Cemented Femoral Hip Replacements [PhD thesis]. Trinity College Dublin; April 2000.
2004	Britton JR. Failure of Cemented Hip Implants Under Complex Loading: Experimental and Numerical Analysis [PhD thesis]. Trinity College Dublin; March 2004.
1994	Duffy BW. A Three-Dimensional Boundary Element-Finite Element Analysis of the Porous Coating-Bone Interface [PhD thesis]. Tulane University; March 31, 1994.
1998	Barich FC. Global Micromotion of Noncemented Components Used in Total Hip Arthroplasty [PhD thesis]. University of Iowa; May 1998.
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