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PubMed2002

Role of surface roughness of titanium versus hydroxyapatite on human bone marrow cells response.

This study was designed to assess human bone marrow cell response and particularly cell adhesion, proliferation, and differentiation, when cultured in vitro on titanium alloy and hydroxyapatite with different values of surface roughness. A further aim was to compare the cell response on the two materials, currently used in spinal surgery. Cell adhesion was determined after 0.5, 2, 4, and 18 hours of incubation; proliferation after 8, 11, 14, and 16 days of culture; and differentiation was evaluated with the expression of alkaline phosphatase activity after 8 and 16 days of culture. This study showed that bone marrow cells grew faster on titanium alloy than on hydroxyapatite, although fewer cells attached to titanium, compared to those attached to hydroxyapatite. No statistically significant difference was observed as the expression of alkaline phosphatase activity on hydroxyapatite and titanium alloy of the same roughness. Cell adhesion, proliferation, and differentiation are dependent on surface roughness of the biomaterial, and all three increased as the roughness of titanium alloy increased. Conclusively, surface roughness of titanium and hydroxyapatite significantly influences bone marrow cell response, and therefore these biomaterials should be used with rough outer surface, if a significant cell response on them is desired. These advantages of titanium and hydroxyapatite theoretically seem to be of particular importance in the following situations: long fusions, lumbosacral fusion, revision surgery with poor bone bank, neuropathic scoliosis associated with few bone graft reserves, and adult patients with severe osteoporosis.

Alloys↗
PubMed2006

Hydroxyapatite dip coated and uncoated titanium poly-axial pedicle screws: an in vivo bovine model.

STUDY DESIGN: A 1-year-old calf was implanted with titanium pedicle screws either uncoated (n = 7) or coated with hydroxyapatite (n = 7) by the dipping method on the pedicles of vertebrae (t10-l3). OBJECTIVE: To evaluate biomechanical and histomorphologic responses to titanium pedicle screws uncoated and coated with hydroxyapatite. SUMMARY OF BACKGROUND DATA: Failure of fixation caused by loosening of pedicle screws is a problem in spinal surgery. Enhancement of the fixation ability of screws by coating with biocompatible materials may improve prognosis of surgery. METHODS: The calf was euthanized 4 months after implantation for determination of insertion and extraction torques for screws, and histologic and scanning electron microscopic examinations of areas screw embedded. RESULTS: Insertion torques did not differ by the kind of screws (99 +/- 5.7 Ncm). However, extraction torques for screws coated with hydroxyapatite were higher than for screws uncoated (249 vs. 133 Ncm, P < 0.01). As compared with uncoated screws, implanted areas for hydroxyapatite-coated screws were denser, had more cracks, and provided better bonding. Fibrous tissue and new bone formation were observed around the areas of uncoated and hydroxyapatite-coated screws embedded, respectively. CONCLUSIONS: Hydroxyapatite coating of titanium pedicle screws by the dipping method improved fixation and vertebral bone-implant interface, suggesting a decreased risk of a screw-loosening problem.

Animals↗
PubMed2005

Heterogeneous nucleation of hydroxyapatite on protein: structural effect of silk sericin.

Acidic proteins play an important role during mineral formation in biological systems, but the mechanism of mineral formation is far from understood. In this paper, we report on the relationship between the structure of a protein and hydroxyapatite deposition under biomimetic conditions. Sericin, a type of silk protein, was adopted as a suitable protein for studying structural effect on hydroxyapatite deposition, since it forms a hydroxyapatite layer on its surface in a metastable calcium phosphate solution, and its structure has been reported. Sericin effectively induced hydroxyapatite nucleation when it has high molecular weight and a beta sheet structure. This indicates that the specific structure of a protein can effectively induce heterogeneous nucleation of hydroxyapatite in a biomimetic solution, i.e. a metastable calcium phosphate solution. This finding is useful in understanding biomineralization, as well as for the design of organic polymers that can effectively induce hydroxyapatite nucleation.

Anisotropy↗
PubMed2004

Porosity variation in hydroxyapatite and osteoblast morphology: a scanning electron microscopy study.

The biocompatibility of hydroxyapatite has been demonstrated by previous studies, with enhancement of osteointegration through the use of porous hydroxyapatite (pHA). Emphasis has been focused on the use of coralline hydroxyapatite or the introduction of macroporosity into synthetic hydroxyapatite. The current study investigates the role of macro- and microporosities in synthetic phase-pure porous hydroxyapatite on the morphological aspects of human osteoblast-like cells using scanning electron microscopy. Cells were seeded on four different types of porous hydroxyapatite (HA1, HA2, HA3 and HA4) and examined following 1, 2, 14 and 30 days of incubation in vitro. The results indicated that the cells had an affinity to micropores through filopodia extensions, at initial stage of attachment. Cellular proliferation and colonization was evident on all materials with cells forming cellular bridges across the macropores at day 14 with cellular canopy formation covering entire macropores observed by day 30. This study demonstrates that while the introduction of microporosity has no evident effect on cellular morphology at later time points, it seems to play a role in initial cellular anchorage and attachment.

Bone and Bones↗
PubMed2004

Evidence of chemisorption of maleic acid to enamel and hydroxyapatite.

Maleic acid has been used as an etchant or non-rinse conditioner in adhesive dentistry. However, the inherent mechanisms of the interaction of maleic acid with hydroxyapatite/enamel have never been fully elucidated. The purpose of this study was to provide evidence for the chemisorption of maleic acid onto hydroxyapatite/enamel, and to identify the reaction products obtained following the interaction of maleic acid with hydroxyapatite. Hydroxyapatite particles were dissolved in a 15% (w/v) aqueous solution of maleic acid (pH = 0.98). Half of the solution was dried to obtain a desiccated mixture. This mixture, hydroxyapatite, maleic acid and self-prepared calcium maleate were analysed by X-ray diffraction (XRD). Acetone was added to the other half of the solution to obtain a precipitate. This precipitate, hydroxyapatite, maleic acid, unetched enamel and maleic acid-etched enamel were analysed by X-ray photoelectron spectroscopy (XPS). The precipitate was also analysed by (1)H NMR. A new binding energy, indicating carboxylate groups, was detected by XPS on the precipitate and maleic acid-etched enamel surface. XRD data indicated the formation of calcium maleate and calcium hydrogen phosphate after the reaction. NMR data revealed that one carboxylic group of maleic acid reacted with hydroxyapatite. Hence, maleic acid can chemisorb to hydroxyapatite and enamel via ionic interactions.

Acid Etching, Dental↗
PubMed2005

Surgical coverage of exposed hydroxyapatite implant with retroauricular myoperiosteal graft.

BACKGROUND: With the increasing use of hydroxyapatite orbital implants, the complication of exposure has become apparent to oculoplastic surgeons. Many kinds of patch grafts, such as sclera, dermis, and hard palate mucosa, have been used to cover exposed hydroxyapatite implants with inconsistent results. In this study, the authors use a newly developed technique, autogenous retroauricular myoperiosteal graft, and the results are reported. METHODS: A piece of retroauricular muscle together with its underlying periosteum was carefully harvested. This myoperiosteal graft was patched to the debrided hydroxyapatite exposure area with the periosteal surface facing outward. The margin of periosteal surface was secured with conjunctiva and left uncovered for the surrounding conjunctiva to epithelialise. RESULTS: Nine eyes with hydroxyapatite exposure more than 3 mm were managed with autogenous retroauricular myoperiosteal grafts. Seven cases were successfully treated with single graft surgery. The other two cases needed an additional graft surgery, and there was no re-exposure noted thereafter. Five patients received a successful insertion of the motility peg. All nine patients have been fitted with prosthesis with reasonable motility. There were no complication noted during more than 1 year of follow up. CONCLUSION: The thick composite nature of the myoperiosteal graft provides a durable and vascularised coverage for exposed hydroxyapatite implants. This technique offers an encouraging alternative for the management of exposed hydroxyapatite implants.

Adult↗
PubMed2002

Long term follow up of bone derived hydroxyapatite orbital implants.

AIMS: To document the long term experience of bone derived hydroxyapatite orbital implants and compare results using scleral wrapped implants with those not using sclera. METHODS: This retrospective case series reviewed the long term follow up of 118 patients with 120 eyes which had undergone enucleation and bone derived hydroxyapatite orbital implant insertion at Dunedin Hospital from 1977 until 2000. Patient details were obtained from theatre records, case note review, patient interview and examination, interview of patient relatives, and family general practitioner records. RESULTS: Of the 120 eyes 84 had bone derived hydroxyapatite orbital implants with sclera and 36 without sclera. Follow up was 0.5-25 years (mean 8.9 years). 25 (19.3%) suffered minor complications of limited exposure of the implant which resolved spontaneously, with implant drilling or wound resuture. Nine (7.5%) suffered major complications requiring explantation. Major complications were more likely in cases with major tissue disruption, ischaemia, or inflammation. There were significantly fewer complications in the group where a bone derived hydroxyapatite orbital implant was implanted without a scleral covering (p<0.05). CONCLUSIONS: The placement of a bone derived hydroxyapatite orbital implant in the socket was associated with a low rate of long term complications and good cosmesis in most cases. The omission of a scleral covering over the hydroxyapatite sphere had some advantages and may prove to be the procedure of choice.

Adolescent↗
PubMed2001

A trial to prepare biodegradable collagen-hydroxyapatite composites for bone repair.

This paper is a trial to prepare collagen-hydroxyapatite composites in vitro by an alternate immersion method. Collagen sponges of different biodegradabilities were prepared through chemical cross-linking of Type I collagen with glutaraldehyde (GA) at concentrations of 0.2, 1.0, and 2.0 wt%. The sponges were immersed at 37 degrees C in Tris-HCl-buffered solution containing 200 mM CaCl2 (pH 7.4) for 2 h and then in an aqueous solution of 120 mM Na2HPO4 (pH 9.3) for a 2 h further (one immersion cycle). The alternate immersion cycle was repeated for different times to obtain collagen-hydroxyapatite composites. The characterization of the resulting composites was performed by Fourier transform infrared spectroscopy (FT-IR). X-ray diffraction (XRD), and scanning electron microscopy (SEM). The weight of composites increased with an increase in immersion cycles and the rate of increase became greater with higher GA cross-linking levels for collagen sponge preparation. The pH of the phosphate solution decreased with the immersion cycle, which suggests H+ generation accompanied hydroxyapatite formation. Irrespective of the GA concentration and immersion cycle, every composite showed IR absorption bands attributable to phosphate and hydroxyl groups at 950-1100 or 550-650 and 3000-3500 cm(-1) and broad peaks specific to hydroxyapatite on the XRD charts. SEM study revealed small white clusters of hydroxyapatite interspersed uniformly on/in the collagen framework without any preferential orientation. The composite prepared from 0.2 wt% GA cross-linked collagen sponge which showed favourable characteristics was applied to a rat skull defect to evaluate its osteoconductivity as well as biodegradability. The formation of new bone tissue was histologically observed at the defect 12 weeks after application in marked contrast to the collagen sponge alone. The composite degraded without any inflammation reaction. It is concluded that the collagen-hydroxyapatite composite prepared by the present method is a biodegradable biomaterial of osteoconductivity applicable to bone repair.

Animals↗
PubMed1995

Salivary amylase promotes adhesion of oral streptococci to hydroxyapatite.

Recent studies have demonstrated that several species of oral streptococci, such as Streptococcus gordonii, bind soluble salivary alpha-amylase. The goal of the present study was to determine if amylase immobilized onto a surface such as hydroxyapatite can serve as an adhesion receptor for S. gordonii. Initially, human parotid saliva was fractionated on Bio-Gel P60, and fractions were screened for their ability to promote adhesion of S. gordonii to hydroxyapatite. Fractions containing alpha-amylase and proline-rich proteins promoted the adhesion of [3H]-labeled S. gordonii to hydroxyapatite. Similar findings were obtained with purified amylase and acidic proline-rich protein 1 (PRP1). Incubation of S. gordonii G9B in the presence of starch and maltotriose increased the binding of this strain to amylase-coated hydroxyapatite, while the adhesion of S. sanguis 10556 to amylase-coated hydroxyapatite was not affected by these saccharides. These results suggest that amylase may serve as a hydroxyapatite pellicle receptor for amylase-binding streptococci. Furthermore, starch and starch metabolites may enhance the adhesion of amylase-binding streptococci to amylase in dental pellicles to augment the formation of dental plaque.

Adhesins, Bacterial↗
PubMed2005

Hydroxyapatite-coated external fixation pins.

The aim of this review is to report on studies of hydroxyapatite-coated external fixation pins as a solution to enhance pin fixation. In a highly loaded animal study, three tapered pin types were compared: Type A uncoated, Type B coated with hydroxyapatite and Type C coated with titanium. There was a 13-fold increase in the extraction torque of Type B pins compared with Type A, and a twofold increase compared with Type C pins. Extraction torque was significantly lower compared with the corresponding insertion torque in both Types A (p < 0.001) and C (p = 0.003). Conversely, with the hydroxyapatite-coated pins there was no difference between extraction and insertion torque. In a clinical study of 76 external fixation pins in 19 patients treated with hemicallotasis for osteoarthritis on the medial side of the knee, pin insertion and extraction torque forces were measured. The patients were randomized to be treated with either standard tapered pins or tapered pins coated with hydroxyapatite. Extraction torque of the hydroxyapatite-coated pins was higher than the extraction torque of the standard pins in both cancellous and cortical bone (p < 0.005). In a prospective, randomized clinical study of osteoporotic wrist fractures, extraction torque of the coated pins was higher than with standard pins (p < 0.0001). These studies demonstrate that with the use of hydroxyapatite-coated pins, no deterioration of pin fixation occurs, and that there is no significant pin loosening and infection, regardless of bone type and loading conditions.

Animals↗
PubMed2000

Normal osteoconduction and repair in and around submerged highly bisphosphonate-complexed hydroxyapatite implants in rat tibiae.

BACKGROUND: Ceramic hydroxyapatite implants have been used in dentistry for their unique compatibility with alveolar bone. Recently it was reported that bisphosphonates may be beneficial in preventing alveolar bone destruction associated with natural and experimental periodontal disease. Furthermore, bisphosphonate does prevent resorption of alveolar bone following mucoperiosteal flap surgery. We undertook a preliminary study evaluating the effects of highly bisphosphonate-complexed hydroxyapatite implants on osteoconduction and repair in rat tibiae. METHODS: Porous hydroxyapatite implants were pre-incubated in 10(-2)M bisphosphonate solutions at pH 3.49 and pH 7.32. The implants had a diameter of 2.1 mm and a height of 2 mm and adsorbed 115 microg bisphosphonate in vitro. Bisphosphonate/hydroxyapatite implants and plain hydroxyapatite implants were inserted in opposite tibial metaphyses of 35 rats. The measurement errors for the mineral density (MD) of the implants and the proximal trabecular mineral bone density (TD) were estimated by peripheral computed tomography and the bone mineral density (BMD) measurement error by dual x-ray absorptiometry. RESULTS: The measurement errors for the MD of the implants and the TD by peripheral computed tomography were 0.81% and 1.96%, respectively ex vivo. The BMD measurement error estimated by dual x-ray absorptiometry was 0.51% ex vivo. TD and BMD for bisphosphonate/hydroxyapatite implants were insignificantly higher compared to plain hydroxyapatite implants. Bisphosphonate/hydroxyapatite pre-incubated at pH 7.32 were found to be nondegradable implants, while bisphosphonate/hydroxyapatite (pH 3.49) implants were slowly degradable and lost a significant 5% of their density. Histologically, all bisphosphonate/hydroxyapatite implants appeared to be fully integrated and effective as bone replacement material in rat tibial bone. They exhibited vascularization and osteoconduction of tibial bone growth along and inside their porous structure. CONCLUSIONS: Our study suggests that normal osteoconduction and repair occurred in and around the highly bisphosphonate-complexed hydroxyapatite implants in rat tibiae.

Absorptiometry, Photon↗
PubMed2003

Comparison of porous-coated titanium femoral stems with and without hydroxyapatite coating.

BACKGROUND: The purpose of this prospective, randomized study was to evaluate the clinical and radiographic results associated with proximally porous-coated titanium stems that were identical in geometry but differed with regard to proximal surface treatment (with or without hydroxyapatite coating). METHODS: A prospective, randomized study was performed to evaluate fifty patients (100 hips) who had undergone sequential bilateral primary total hip replacement. A proximally porous-coated titanium stem with hydroxyapatite coating was implanted on one side and a proximally porous-coated titanium stem without hydroxyapatite coating was implanted on the other side during the same operative setting in all fifty patients. A cementless acetabular component made of titanium was used in all hips. There were thirty-six men and fourteen women; the mean age at the time of the operation was 45.3 years. The mean duration of follow-up was 6.6 years. Clinical and radiographic evaluations were performed preoperatively; at six weeks; at three, six, and twelve months; and yearly thereafter. RESULTS: The Harris hip scores in the hydroxyapatite-coated group (mean, 94 points) and non-hydroxyapatite-coated group (mean, 92 points) were similar at the final follow-up examination. The prevalence of transient pain in the thigh was 4% in each group. No acetabular or femoral component demonstrated aseptic loosening. Bone-remodeling patterns, including calcar atrophy, were similar in the two groups. No acetabular or femoral osteolysis was seen. CONCLUSIONS: At a mean of 6.6 years postoperatively, the clinical and radiographic results associated with proximally porous-coated femoral prostheses with identical geometries that differed only with regard to the presence or absence of hydroxyapatite coating were similar.

Adult↗
PubMed2004

Comparison of a hydroxyapatite-coated sleeve and a porous-coated sleeve with a modular revision hip stem. A prospective, randomized study.

BACKGROUND: Bone ingrowth into a cementless prosthesis can be achieved by both porous and hydroxyapatite coatings. The purpose of this study was to compare the performance of a hydroxyapatite-coated proximal sleeve and a porous bead-coated sleeve in patients managed with a modular revision hip system. METHODS: Between August 1992 and December 1996, fifty-three consecutive femoral revisions performed with an S-ROM stem in fifty-two patients were prospectively randomized at the time of surgery to either a hydroxyapatite-coated or a porous-coated sleeve. All patients were evaluated clinically and radiographically at three months, six months, and yearly for a minimum of two years (average, four years; range, two to 7.5 years). Femoral defects were classified according to the criteria of Paprosky et al. Six patients died and four patients were lost to follow-up, leaving forty-two patients (forty-three hips) as the final study group. RESULTS: For the entire group, two femoral stems, one of which had been implanted in a hip with a Paprosky type-II femoral defect and the other in a hip with a Paprosky type-IIIB femoral defect, required a repeat revision, one for pain and the other for aseptic loosening. Radiographic evidence of bone ingrowth was observed in 96% (twenty-six) of the twenty-seven femora with type-I or II defects and in 81% (thirteen) of the sixteen femora with type-III defects. Femoral component survival, with use of revision as the end point, was 95% at four years for the entire group. The Harris hip scores were not significantly different when stratified by implant type, but were significantly different when stratified by bone loss (p < 0.05). In the femora with type-I or II defects, no difference was detected between those treated with a hydroxyapatite-coated implant and those that received a porous-coated implant with respect to bone ingrowth. However, in femora with type-III defects, the likelihood of the development of bone ingrowth was 2.6 (95% confidence interval, 1.3 to 5.17) times greater in hips that received a hydroxyapatite-coated implant (all eight developed ingrowth) than in hips that had a porous-coated implant (five of eight developed ingrowth) (p = 0.05). CONCLUSIONS: Bone fixation was achieved more often with hydroxyapatite-coated sleeves in femora with Paprosky type-III defects, but no significant difference was noted in outcomes between the two implant types when used in bone with type-I or type-II femoral defects. Overall, the S-ROM modular hip stem performed better in femora with type-I or II bone defects than in femora with type-III defects. LEVEL OF EVIDENCE: Prognostic study, Level II-1 (retrospective study). See Instructions to Authors for a complete description of levels of evidence.

Adult↗
PubMed2001

In vivo histological changes occurring in hydroxyapatite cranial reconstruction--case report.

Histological changes were observed in a hydroxyapatite plate and hydroxyapatite granules used to repair a craniotomy defect and removed after 2 years and 9 months of use. The hydroxyapatite plates and granules had completely fused to the cranium, with new bone formation on the dural side extending in a three-dimensional matrix along the pores with the Haversian system in the center. New bone formation was less extensive under the artificial dura than under normal dura. This finding suggests that the dura has the ability to promote bone formation. A new vessel was found along the interconnecting pores. The interconnecting pores allow osteoconduction in the hydroxyapatite plate, so new bone formation can progress. Hydroxyapatite has osteoconduction properties and is biocompatible, so gains strength in vivo through new bone formation, and is the ideal material for artificial bones. Factors important to achieving good bone formation after cranial reconstruction surgery include presence of the dura, and pore size approximate to the Haversian system (100-500 microns) and interconnecting pores in the hydroxyapatite plate.

Adult↗
PubMed2003

[The role of synthetic hydroxyapatite solution in the destructive process of arteriosclerosis].

Presented work is a pilot research on dissolving of homogeneous synthetic hydroxyapatite, being chemically analogous to the hydroxyapatite formed in human organism. Crystallization of hydroxyapatite (HA) in human arteries also known as calcification is a complex process leading to dysfunctions in the functioning of human blood system and--in effect--to dysfunction in functioning of tissues and organs [1]. Mineralization of blood vessels is a complicated process and can appear in two forms: visible and hidden, which can be organic or inorganic [2]. With inorganic mineralization there are concerned primarily phosphoranes of Calcium, mostly apathites, while the organic mineralization is represented by organic substances like cholesterol, fats, lipids [2, 3]. The forming of crystals, fats, lipids etc. in arteries is an effect of continuation of the processes started by hidden mineralization [1]. Research was focused on the possibilities of dissolving the visible, inorganic mineralization, represented by synthetic hydroxyapatite. In the work, there are presented preliminary results of biochemical studies on dissolving of the synthetic hydroxyapatite. The processes of dissolving of this compound took place in dynamic conditions. The organic solutions of hawthorn, onion and garlic of various concentrations--2.5%, 5%, 7.5%--were used as the solvents. These herbs show anti-calcification effects. The preliminary results of the experiments confirm the hypothesis that the solutions of these herbs free the Ca and P ions from the grains of synthetic HA (in varying flowing pH and speed conditions). This research encourages further analysis of the processes of dissolving hydroxyapatite--either synthetic or coming from human body.

Antioxidants↗
PubMed2004

Integrated hydroxyapatite implant and non-integrated implants in enucleated Asian patients.

INTRODUCTION: This study compares the outcome and complications of integrated hydroxyapatite implant and non-integrated orbital implants following enucleation in Asian patients. MATERIALS AND METHODS: This is a retrospective study of enucleated patients with coralline hydroxyapatite implants versus non-integrated implants (acrylic, glass and silicone) at the Singapore National Eye Centre from January 1991 to December 2000. The outcomes measured were implant migration, extrusion, socket infection, conjunctival dehiscence and implant exposure. Statistical analysis was done using the 2-sample t-test. RESULTS: Twenty-one patients had the hydroxyapatite implant and 38 non-integrated implants (27 acrylic, 9 glass and 2 silicone). The mean duration of follow-up was 2.7 years and 4 years for the hydroxyapatite implant and non-integrated implants respectively. Three patients with pre-existing severe socket contracture before enucleation surgeries were excluded from the study. Four cases of implant migration, 4 cases of implant extrusion and 3 cases of socket infection were encountered; all were sockets fitted with non-integrated implants. There was a higher rate of conjunctival dehiscence for sockets with hydroxyapatite implants (6 out of 21) compared to sockets with non-integrated implants (3 out of 35). This was statistically significant (P = 0.048). CONCLUSIONS: Implant complications of migration, extrusion and socket infection were found in non-integrated implants and none in coralline hydroxyapatite implants, which had a significantly higher rate of conjunctival dehiscence. Most of these were easily managed with only a small number progressing to implant exposure.

Adult↗
PubMed1995

Hydroxyapatite-coated proximal ingrowth femoral stems. A matched pair control study.

A matched pair study of 2 groups of 42 uncemented total hip replacements were compared retrospectively after a minimum 3-year followup. Forty-two hips were implanted with a hydroxyapatite coating on the proximal femoral patched porous surfaces; 42 hips had patched porous-coated stems without hydroxyapatite. There were no clinical differences between the matched groups by any criteria of measurement. There was no statistically significant difference between the matched groups for femoral stem fixation at all followup intervals. At the 3-year followup, 90% of the femoral stems in the hydroxyapatite porous group, and 83% in the porous control group achieved stable bony fixation. Hydroxyapatite-coated femoral stems demonstrated accelerated bone remodeling characterized by proximal cancellous hypertrophy. The percentage of femoral stems exhibiting cancellous hypertrophy was significantly greater at all followup intervals. This study did not demonstrate any clinical advantage of hydroxyapatite being added to a porous-coated surface. The radiographic changes of bone remodeling seen with hydroxyapatite are not known to improve durability of the hip arthroplasty. This study again condemns the use of patched porous-coating and titanium-bearing surfaces.

Adult↗
PubMed1994

Development of hybrid type artificial bone marrow using sintered hydroxyapatite.

In vivo inducement of hybrid-type artificial bone marrow with hemopoietic inductive microenvironment (HIM) in sintered hydroxyapatite (HA) chamber was carried out. This research is important to disclose the mechanisms of hemopoiesis and is useful for clinical application. In the evolution of vertebrates, cartilage of the inner skeleton changed into bone, having biomechanical properties to form bone marrow cavities. The hemopoietic nests immigrated into the cavities from the spleen. We should be able to induce hemopoietic nests in a hydroxyapatite chamber in place of bone, if we can find optimal structural conditions. Therefore, we tried to artificially induce a hematopoietic field in muscles using sintered porous tubular hydroxyapatite and new type hydroxyapatite plate made by high-pressure gas technique. As a result, not only in the pore sites of tubular hydroxyapatite artificial bone, but at the surface of the new type hydroxyapatite plate implanted in the dorsal muscles, marked differentiation of bone marrow cell clusters of the hematopoietic field could be observed.

Animals↗