Slide track analysis of the relative motion between femoral head and acetabular cup in walking and in hip simulators.

Joint simulators are important tools in wear studies of prosthetic joint materials. The type of motion in a joint simulator is crucial with respect to the wear produced. It is widely accepted that only multidirectional motion yields realistic wear for polyethylene acetabular cups. Multidirectionality, however, is a wide concept. The type of multidirectional motion varies considerably between simulators, which may explain the large differences in observed wear rates. At present, little is known about the relationship between the type of multidirectional motion and wear. One illustrative way to compare the motions of various hip simulators is to compute tracks made on the counterface by selected points of the surface of the femoral head and acetabular cup due to the cyclic relative motion. A new computation method, based on Euler angles, was developed, and used to compute slide tracks for the three-axis motion of the hip joint in walking, and for two hip simulators, the HUT-3 and the biaxial rocking motion. The slide track patterns resulting from the gait waveforms were found to be similar to those produced by the HUT-3 simulator. This paper is the first to include a verification of the computed simulator tracks. The tracks were verified in the two simulators using sharp pins, embedded in acetabular cups, engraving distinct grooves onto the femoral heads. The engravings were identical to the computed tracks. The results clearly differed from earlier computations by another research group. This study is intended to start a thorough investigation of the relationship between the type of multidirectional motion and wear.

[1]  V. Saikko,et al.  Type of motion and lubricant in wear simulation of polyethylene acetabular cup , 1999, Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine.

[2]  John J. Craig,et al.  Introduction to Robotics Mechanics and Control , 1986 .

[3]  J. Lewis,et al.  A note on the description of articulating joint motion. , 1977, Journal of biomechanics.

[4]  A Sarmiento,et al.  The origin of submicron polyethylene wear debris in total hip arthroplasty. , 1995, Clinical orthopaedics and related research.

[5]  V O Saikko,et al.  A Three-Axis Hip Joint Simulator for Wear and Friction Studies on Total Hip Prostheses , 1996, Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine.

[6]  W H Harris,et al.  Loci of movement of selected points on the femoral head during normal gait. Three-dimensional computer simulation. , 1996, The Journal of arthroplasty.

[7]  I. Faux,et al.  Computational Geometry for Design and Manufacture , 1979 .

[8]  W H Harris,et al.  Analysis of the kinematics of different hip simulators used to study wear of candidate materials for the articulation of total hip arthroplasties , 1998, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[9]  G. Smidt,et al.  Measurement of hip joint motion during walking , 1969 .

[10]  T. Andriacchi,et al.  Musculoskeletal dynamics, locomotion, and clinical applications , 1991 .

[11]  M P Kadaba,et al.  On the estimation of joint kinematics during gait. , 1991, Journal of biomechanics.

[12]  V. Saikko,et al.  Wear simulation of total hip prostheses with polyethylene against CoCr, alumina and diamond-like carbon. , 2001, Biomaterials.

[13]  R Baker,et al.  Movement loci of selected points on the femoral head for individual total hip arthroplasty patients using three-dimensional computer simulation. , 2000, The Journal of arthroplasty.

[14]  M. Ungethm,et al.  Ein neuer Simulator zur Testung von Totalendoprothesen fr das Hftgelenk@@@A new simulating system for artificial hip joints , 1973 .

[15]  Wilson C. Hayes,et al.  Basic Orthopaedic Biomechanics , 1995 .

[16]  D Dowson,et al.  Design and development of a versatile hip joint simulator and a preliminary assessment of wear and creep in Charnley total replacement hip joints. , 1988, Engineering in medicine.

[17]  P Slätis,et al.  A Five-Station Hip Joint Simulator for Wear Rate Studies , 1992, Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine.

[18]  V. Saikko,et al.  A multidirectional motion pin-on-disk wear test method for prosthetic joint materials. , 1998, Journal of biomedical materials research.

[19]  M Ungethüm,et al.  [A new simulating system for artificial hip joints (author's transl)]. , 1973, Archiv fur orthopadische und Unfall-Chirurgie.

[20]  Brian J. Edwards,et al.  Orientation softening in the deformation and wear of ultra-high molecular weight polyethylene , 1997 .

[21]  John J. Craig Zhu,et al.  Introduction to robotics mechanics and control , 1991 .

[22]  V V Surin.  Loci of movement of selected points on the femoral head during normal gait: three-dimensional computer simulation. , 1997, The Journal of arthroplasty.

[23]  M Viceconti,et al.  Discussion on the design of a hip joint simulator. , 1996, Medical engineering & physics.

[24]  J. P. Paul.  Approaches to design - Force actions transmitted by joints in the human body , 1976, Proceedings of the Royal Society of London. Series B. Biological Sciences.