Histological and biomechanical analysis of bone and interface reactions around hydroxyapatite-coated intramedullary implants of different stiffness: a pilot study on the goat.

We hypothesized that reduced stem stiffness of orthopaedic implants contributes to a high risk of loosening, since interface stresses and relative motions may exceed a tolerable range. To study this hypothesis, three types of load-bearing implant with different stiffnesses were inserted into the tibia of the goat. Histological analysis was performed of bone repair after insertion of the implant, bone ingrowth, interface disruption and loosening. A finite element model of the configuration provided the quantitative range of interface stresses and relative motions for the present experiment. The implants were made out of stainless steel, hollow titanium and a thin titanium core covered with a polyacetal coating. The stiffness ratios of these implants were approximately 10:4:1, respectively. All implants were coated with a layer of hydroxyapatite (HA) in order to minimize the possible biological effects of the different implant materials. Irrespective of the type of implant, there was a repair phase that lasted 6-12 weeks. The stiff implants functioned well. Large areas of bone bonding to the HA layer were found after the repair phase at 12 weeks postoperatively. After 24 weeks, some signs of loosening were observed. More loosening occurred with the hollow titanium and polyacetal implants, mainly during the repair phase. Three hollow titanium and three polyacetal coated implants survived this period, and were killed after 24 weeks. The integrity of the HA layer at the bone-implant interface of the titanium implants was good. In the polyacetal implants, the repair reaction of the cortical bone was incomplete. Bone ingrowth into HA was largely lacking. In conclusion, we found significant differences in the repair and interface reactions around implants of different stiffness. Stiff implants showed favourable initial interface conditions for bone ingrowth. Intermediate and flexible implants provoked unfavourable interface conditions for initial bone ingrowth. The finite element study showed that the flexible stems produce larger micromotions and higher interface stresses at the bone-prosthesis interface than the stiff stems, indicating an explanation for the histological findings.

[1]  P Herberts,et al.  Prognosis of total hip replacement: A Swedish multicenter study of 4,664 revisions , 1990 .

[2]  C. Engh,et al.  Producing and avoiding stress shielding. Laboratory and clinical observations of noncemented total hip arthroplasty. , 1992, Clinical orthopaedics and related research.

[3]  C. Bünger,et al.  Bone graft incorporation around titanium-alloy- and hydroxyapatite-coated implants in dogs. , 1992, Clinical orthopaedics and related research.

[4]  A. Nachemson.  Low-back pain. Are orthopedic surgeons missing the boat? , 1993, Acta orthopaedica Scandinavica.

[5]  A Sarmiento,et al.  Radiographic analysis of a low-modulus titanium-alloy femoral total hip component. Two to six-year follow-up. , 1985, The Journal of bone and joint surgery. American volume.

[6]  M. Freeman,et al.  The effect of hydroxyapatite coating on ingrowth of bone into cavities in an implant. , 1991, The Journal of arthroplasty.

[7]  R. Huiskes,et al.  Intramedullary fixation with screwed, conical stems--unsolicited results from animal experiments. , 1992, Clinical materials.

[8]  M. Schünke,et al.  Subchondral bone formation in arthrosis. Polychrome labeling studies in mice. , 1988, Acta orthopaedica Scandinavica.

[9]  J. M. Lee,et al.  Observations on the Effect of Movement on Bone Ingrowth into Porous‐Surfaced Implants , 1986, Clinical orthopaedics and related research.

[10]  S D Cook,et al.  Hydroxyapatite-coated titanium for orthopedic implant applications. , 1988, Clinical orthopaedics and related research.

[11]  T. Yamamuro,et al.  Bonding behavior of three types of hydroxyapatite with different sintering temperatures implanted in bone. , 1988, Clinical orthopaedics and related research.

[12]  P. Jalovaara,et al.  Total hip arthroplasty using isoelastic femoral stems. A seven- to nine-year follow-up in 108 patients. , 1994, The Journal of bone and joint surgery. British volume.

[13]  Jan Ypma.  Strength and ingrowth aspects of porous acrylic bone cement: an experimental study of possible applications of porous acrylic bone cement in total hip replacement , 1981 .

[14]  S D Cook,et al.  Biologic response to hydroxylapatite-coated titanium hips. A preliminary study in dogs. , 1989, The Journal of arthroplasty.

[15]  B. Hainau,et al.  Porous-coated knee arthroplasty. A case report concerning bone ingrowth. , 1989, Clinical Orthopaedics and Related Research.

[16]  M. Semlitsch,et al.  Reaction of bone to methacrylate after hip arthroplasty: a long-term gross, light microscopic, and scanning electron microscopic study. , 1974, The Journal of bone and joint surgery. American volume.

[17]  P. Buma,et al.  Tissue reactions around a hydroxyapatite-coated hip prosthesis. Case report of a retrieved specimen. , 1995, The Journal of arthroplasty.

[18]  T. Bauer,et al.  Hydroxyapatite-coated femoral stems. Histological analysis of components retrieved at autopsy. , 1991, The Journal of bone and joint surgery. American volume.

[19]  R. Haddad,et al.  Biologic response to hydroxylapatite-coated titanium hips , 1989 .

[20]  S. Perren,et al.  Xylenol orange, a fluorochrome useful in polychrome sequential labeling of calcifying tissues. , 1971, Stain technology.

[21]  W H Harris,et al.  The synovial-like membrane at the bone-cement interface in loose total hip replacements and its proposed role in bone lysis. , 1983, The Journal of bone and joint surgery. American volume.

[22]  Michael Jarcho,et al.  Calcium phosphate ceramics as hard tissue prosthetics. , 1981, Clinical orthopaedics and related research.

[23]  H Weinans,et al.  Adaptive bone remodeling and biomechanical design considerations for noncemented total hip arthroplasty. , 1989, Orthopedics.

[24]  C. Klein,et al.  Chemical implant fixation using hydroxyl-apatite coatings. The development of a human total hip prosthesis for chemical fixation to bone using hydroxyl-apatite coatings on titanium substrates. , 1987, Clinical orthopaedics and related research.

[25]  H. Hansson,et al.  Structural aspects of the interface between tissue and titanium implants. , 1983, The Journal of prosthetic dentistry.

[26]  L. Blankevoort,et al.  Reconstruction of bone loading conditions from in vivo strain measurements. , 1995, Journal of biomechanics.

[27]  H Weinans,et al.  Effects of fit and bonding characteristics of femoral stems on adaptive bone remodeling. , 1994, Journal of biomechanical engineering.

[28]  J O Galante,et al.  Endosteal erosion in association with stable uncemented femoral components. , 1990, The Journal of bone and joint surgery. American volume.

[29]  D. Schurman,et al.  A clinical-pathologic-biochemical study of the membrane surrounding loosened and nonloosened total hip arthroplasties. , 1989, Clinical orthopaedics and related research.

[30]  A. Sarmiento,et al.  Radiographic performance of two different total hip cemented arthroplasties. A survivorship analysis. , 1988, The Orthopedic clinics of North America.

[31]  In vivo measurements of the loading conditions on the tibia of the goat. , 1993, Acta anatomica.

[32]  P. Bullough,et al.  The biologic interface between bone and cementless femoral endoprostheses. , 1986, The Journal of arthroplasty.

[33]  R. H. Fitzgerald,et al.  Non-cemented total hip arthroplasty , 1987 .

[34]  K. Donath,et al.  Interface between bone tissue and implants of solid hydroxyapatite or hydroxyapatite-coated titanium implants. , 1989, Biomaterials.

[35]  K. Søballe,et al.  Hydroxyapatite ceramic coating for bone implant fixation. Mechanical and histological studies in dogs. , 1993, Acta orthopaedica Scandinavica. Supplementum.

[36]  J. Galante,et al.  A comparative study of porous coatings in a weight-bearing total hip-arthroplasty model. , 1986, The Journal of bone and joint surgery. American volume.

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

[38]  C. Bünger,et al.  Hydroxyapatite coating modifies implant membrane formation. Controlled micromotion studied in dogs. , 1992, Acta orthopaedica Scandinavica.

[39]  R. Huiskes,et al.  Friction and stem stiffness affect dynamic interface motion in total hip replacement , 1996, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[40]  C. Klein,et al.  Bonding of bone to apatite-coated implants. , 1988, The Journal of bone and joint surgery. British volume.

[41]  A. Rosenberg.  Cementless total hip arthroplasty: femoral remodeling and clinical experience. , 1989, Orthopedics.

[42]  H. Oonishi,et al.  The effect of hydroxyapatite coating on bone growth into porous titanium alloy implants. , 1989, The Journal of bone and joint surgery. British volume.

[43]  W H Harris,et al.  Micromotion of cemented and uncemented femoral components. , 1991, The Journal of bone and joint surgery. British volume.

[44]  H Weinans,et al.  Effects of material properties of femoral hip components on bone remodeling , 1992, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[45]  P. Buma,et al.  A procedure for the visualization of bone with hydroxyl-apatite coated implants. , 1994, Clinical materials.

[46]  R. Huiskes,et al.  The relationship between stress shielding and bone resorption around total hip stems and the effects of flexible materials. , 1992, Clinical orthopaedics and related research.

[47]  C. Engh,et al.  The influence of stem size and extent of porous coating on femoral bone resorption after primary cementless hip arthroplasty. , 1988, Clinical orthopaedics and related research.

[48]  Hwj Rik Huiskes.  Stress patterns, failure modes, and bone remodeling , 1988 .

[49]  Engh Ca,et al.  The influence of stem size and extent of porous coating on femoral bone resorption after primary cementless hip arthroplasty. , 1988 .