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PubMed2000

Hydroxyapatite-enhanced tibial prosthetic fixation.

Sixty-two knees (60 patients) were randomized to four noncemented groups. In Groups 1, 3, and 4, the bone cuts were made with a cooled saw blade. In Group 1, 15 patients were operated on with the porous coated Osteonic 7000 tibial component. In Group 2, 15 patients were operated on with the same tibial component as in Group 1 but with the use of a standard saw blade. In Group 3, 16 patients were operated on with the hydroxyapatite-coated Osteonic tibial component, and in Group 4, 16 patients were operated on with the hydroxyapatite Duracon tibial component. All patients were followed up clinically and with roentgenstereometric analysis. There were no differences among the groups regarding clinical outcome. One knee was revised (Group 2) after 1 year because of loosening of the tibial component. The maximum migration at 1 year was 1.7 mm in Group 1, 1.9 mm in Group 2, 1.3 mm in Group 3, and 1 mm in Group 4. At the 2-year followup, the migrations were 1.8 mm, 1.5 mm, 1.4 mm, and 1 mm in Groups 1, 2, 3, and 4, respectively. The inducible displacement that occurred at 1 year was 0.6 mm in Group 1, 0.5 mm in Group 2, 0.4 mm in Group 3, and 0.4 mm in Group 4. The hydroxyapatite coating had a strong positive effect on the tibial component fixation. No prosthesis in the hydroxyapatite groups showed continuous migration.

Aged↗
PubMed2001

Fixation strength and pin tract infection of hydroxyapatite-coated tapered pins.

In a multicenter, prospective, randomized study, the biomechanical and clinical properties of the bone-pin interface were compared with standard tapered pins and hydroxyapatite-coated tapered pins implanted in patients who underwent femoral and tibial external fixation treatments. The results showed that the hydroxyapatite-coated tapered pins are clinically effective in improving the strength of fixation of the bonepin interface. This improvement corresponded to a lower rate of pin tract infection. In the hydroxyapatite-coated pin group, there were no differences in strength of fixation between the pins removed from the infected and uninfected pin tracts. In this pin group, the mean pin extraction torque was 531 +/- 225 Ncm in the infected pin tracts and 508 +/- 233 Ncm in the uninfected pin tracts. In the standard pin group, the mean pin extraction torque was 73 +/- 142 Ncm in the infected pin tracts and 211 +/- 216 Ncm in the uninfected pin tracts. The advantages provided by the hydroxyapatite-coated pins were higher in cancellous bone than in cortical bone.

Adult↗
PubMed2002

Hydroxyapatite block for use in posterolateral lumbar fusion: a report of four cases.

Autologous bone grafts for posterolateral lumbar fusion are harvested from the iliac crests. Recently, several alternatives to autologous bone have been evaluated (such as graft substitutes, graft extenders, or both) with variable results. However, no clinical long-term studies have validated the efficacy of these techniques in posterolateral lumbar fusion. This study evaluated radiographic and histologic findings in four patients (mean age, 66 years) during the first 5 years after posterolateral fusion with an hydroxyapatite block. The mean followup was 7 years 1 month. Radiologic evaluation was by plain radiographs and computed tomography scans. Histologic evaluation was done in one patient. Capillaries extended into the porous structure of the hydroxyapatite substrate, and some of the pores were replaced by newly formed bone tissue. The long-term results of graft substitutes were stable and hydroxyapatite appeared to have some potential to achieve union in posterolateral lumbar fusion. However, hydroxyapatite block alone has not functioned effectively as a complete graft substitute in posterolateral lumbar fusion. Thus, a suitable osteogenic material is required to induce the formation of new bone and achieve a solid union.

Aged↗
PubMed2002

Experimental osteomyelitis treatment with antibiotic-impregnated hydroxyapatite.

A calcium hydroxyapatite antibiotic implant was evaluated to determine its efficacy as an antibiotic delivery system in a localized osteomyelitis rabbit model. Localized rabbit tibial osteomyelitis was developed with an intramedullary injection of methicillin resistant Staphylococcus aureus. Infected rabbits were randomized and divided into eight groups depending on treatment with or without debridement, systemic antibiotics, antibiotic-impregnated polymethylmethacrylate beads, or calcium hydroxyapatite implants with and without antibiotic impregnation. All treatments began 2 weeks after infection. After 4 weeks of therapy, the involved bones were cultured for concentrations of Staphylococcus aureus per gram of bone. Rabbits (n = 11) that had calcium hydroxyapatite (impregnated with vancomycin) implanted into the dead space after the debridement surgery had an 81.8% infection clearance after treatment. Rabbits (n = 10) that had polymethylmethacrylate beads (impregnated with vancomycin) implanted into the dead space after debridement surgery had a 70% clearance rate. All other treatment modalities resulted in less than 50% clearance rates. Calcium hydroxyapatite may be an effective alternative to polymethylmethacrylate for providing local antibiotic therapy in cases of methicillin resistant Staphylococcus aureus osteomyelitis.

Animals↗
PubMed2003

Plate fixation with hydroxyapatite-coated screws: a comparative loaded study.

The authors evaluated whether AO/ASIF screws coated with hydroxyapatite are better fixed than standard screws in a highly loaded plate fixation animal study. Twelve sheep were divided into two groups. The medial tibial middiaphysis was exposed and a 5-mm long bone cylinder was removed. The tibiae were fixed with six-hole dynamic compression plates. Six sheep received standard AO/ASIF stainless steel cortical screws (Group A), and six sheep received AO/ASIF stainless steel cortical screws coated with hydroxyapatite (Group B). Three months after surgery, the sheep were euthanized. The mean screw insertion torque was 4800 +/- 768 N/mm in Group A and 4847 +/- 450 N/mm in Group B. The mean screw extraction torque was 530 +/- 374 N/mm in Group A and 3733 +/- 849 N/mm in Group B. Extraction torque of Group A was significantly lower compared with the corresponding insertion torque. In Group B, there were no differences between extraction and insertion torque. Morphologic analyses showed marked fibrous tissue encapsulation in Group A and bone to screw direct contact in Group B. The results confirm that hydroxyapatite-coated AO/ASIF screws prevent deterioration of screw anchorage, even under highly loaded conditions. By using hydroxyapatite-coated screws, complications resulting from inadequate fixation could be avoided.

Animals↗
PubMed2002

Frontal sinus obliteration with hydroxyapatite cement.

OBJECTIVE: To evaluate the efficacy hydroxyapatite cement as an alternative to autologous fat in the obliteration of the frontal sinus after trauma or chronic suppuration. METHODS: Single institution, nonrandomized, prospective analysis of patients treated in an academic, tertiary care center. Patients were followed with physical examinations and were monitored for recurrent infections, which would have necessitated removal of the implant. Follow-up radiographs were obtained at 12 months. Standard surgical techniques were used to obliterate the frontal sinus with the addition of the placement of a vascularized pericardial flap along the frontal sinus floor. RESULTS: Eleven patients underwent hydroxyapatite frontal sinus obliteration. There were 2 women and 9 men in the series with age ranges from 33 to 82 years (mean, 48 y). Three patients underwent obliteration for trauma and 8 for chronic infections with or without mucopyocele. The mean follow-up is 27 months (range, 3.3-37 mo). No patient has developed clinical or radiographic evidence of recurrent frontal sinusitis and at this point no implants have been removed. Nine of 11 patients (91%) report complete resolution of all symptoms. CONCLUSION: Hydroxyapatite cement had demonstrated efficacy in full-thickness reconstruction of frontal sinus defects. The pericranial flap may provide a barrier to prevent infection of the implant in the face of acute ethmoid sinusitis. Hydroxyapatite cement offers the advantages of no donor site morbidity and the potential for complete osseointegration.

Adult↗
PubMed1998

Failure of hydroxyapatite cement to set in repair of a cranial defect: case report.

OBJECTIVE AND IMPORTANCE: Hydroxyapatite cement, a new biomaterial that is being marketed as a method for reconstructing cranial defects, offers many advantages. We document, herein, the complete dissolution and failure of this material to set in a surgically dry field, under optimal conditions, an occurrence that has not been previously reported. CLINICAL PRESENTATION: Hydroxyapatite cement was used for reconstruction of a frontal bone defect secondary to a traumatic depressed cranial fracture in a 9-year-old male patient. At the time of suture removal on postoperative Day 6, we observed serous discharge from the wound, a reappearance of the cranial defect, and brain pulsations visible subcutaneously. INTERVENTION: The patient was returned to the operating room, at which time we learned that the hydroxyapatite cement had migrated out of the defect; small concretions of the cement were scattered throughout the subgaleal space. The concretions of cement in the subgaleal space and the small amount of cement remaining in the defect were removed, and titanium mesh was used. An excellent cosmetic result was achieved. CONCLUSION: Although offering many advantages, hydroxyapatite cement does carry a risk of failure to set, despite optimal technique. Causes for failure to set, as well as possible modifications in the use of material and technique, are discussed.

Bone Cements↗
PubMed1995

Bone induction of hydroxyapatite combined with bone morphogenetic protein and covered with periosteum.

Using a rabbit model, we evaluated the role of the periosteum in bone induction using hydroxyapatite ceramic pellets, some of which had been coated with bone morphogenetic protein. Eighteen rabbits were divided into two groups, a control group that received pellets soaked in phosphate-buffered saline alone and another group for which the pellets had been supplemented with bone morphogenetic protein. After making a skin incision on the head of each rabbit, two caudally pedicled periosteal flaps measuring 1 cm in width and 2.5 cm in length were elevated. These flaps were wrapped around hydroxyapatite pellets manufactured from limestone and fixed with sutures. After implantation, both groups of rabbits were returned to their cages, maintained for 3, 6, or 9 weeks [every group consisted of 3 rabbits (6 pellets)], and then sacrificed. In this study, the extent of bone induction, which was measured with a dual x-ray densitometer, that resulted from covering the hydroxyapatite pellet with periosteum alone (control group) was minimal. On the contrary, since osteogenesis from the periosteum toward the pores of the pellet was observed in the bone morphogenetic protein group much more than in the control group, the usefulness of our technique was confirmed. However, active osteogenesis was observed with subperiosteal implantation of the hydroxyapatite-bone morphogenetic protein complex in the bone morphogenetic protein group, but the osteogenesis observed was not distributed over the entire pellet.

Animals↗
PubMed1997

The use of porous granular hydroxyapatite in secondary orbitocranial reconstruction.

The search for the ideal bone-graft substitute has been the focus of many research and clinical studies. Hydroxyapatite is one such material that combines osseointegration with maintenance of implant volume and excellent durability. We present our experience in 29 patients ranging in age from 3 to 22 years (mean age 10.5 years) who underwent secondary orbitocranial reconstruction of large contour defects utilizing porous granular hydroxyapatite. Follow-up ranges from 6 to 72 months (mean 30 months). Indications for secondary surgery included residual bony contour defects of the frontal bone, temporal areas, and superior orbital rims that were present 12 months or more after initial surgery. There was one infection secondary to a chronic seroma necessitating removal of the porous hydroxyapatite, and one patient required revision for underfilling and another for overfilling. Excellent permanent contour improvement was obtained with a smooth skin surface in the remainder of our patients. The contour corrections have been long lasting, without evidence of porous hydroxyapatite resorption or migration.

Biocompatible Materials↗
PubMed1997

Bone remodeling with resorbable bioactive glass and hydroxyapatite.

Particulate resorbable bioactive glass and resorbable hydroxyapatite did not inhibit the growth of periodontal ligament cells and osteoblasts in cultures. Both cell types promoted the activation of alkaline phosphatase around the surface of bioactive glass particles. When bioactive glass and hydroxyapatite were cultured with peripheral blood lymphocytes/monocytes, the number of nonadherent and adherent cells was the same as observed with a control. Resorbable bioactive glass activated the cells necessary for bone formation better than hydroxyapatite and suppressed the formation of osteoclasts for bone resorption. Resorbable bioactive glass and resorbable hydroxyapatite were found to be harmless to periodontium cells and lymphocytes/monocytes.

Absorption↗
PubMed2005

Outcome of an acetabular design with hydroxyapatite coating on a rough substrate.

UNLABELLED: Outcomes of hydroxyapatite-coated cups have not been as consistently successful as outcomes of hydroxyapatite-coated stems; therefore, we studied a newer generation acetabular design with a plasma-sprayed hydroxyapatite coating on an arc-deposited rough titanium substrate. Our objective was to determine whether clinical and radiographic outcomes would be better than reported for earlier-generation designs. Ninety consecutive hips in 85 patients implanted with this design were followed up prospectively for 2 to 5 years after surgery. Hip scores improved from a preoperative mean of 59 (+/- 12) to final followup mean of 91 (+/- 12). One hip was revised for recurrent dislocation. No hips were revised for aseptic loosening. No cup had complete continuous radiolucent lines. Incomplete lucent lines were noted on early postoperative radiographs. With followup, radiolucent line length decreased by a mean 32% and radiolucent line density increased by 9%. Mean polyethylene linear and volumetric head penetration rates were 0.17 (+/- 0.16) mm/year and 73 (+/- 70) mm/year, respectively. Head penetration rates were higher in men. No other factor (age, body weight, cup abduction, or anteversion angle) correlated with head penetration rate. Our study presents encouraging short-term results. Improvement in radiolucent lines suggests a beneficial effect of hydroxyapatite coating on osseointegration of the cup. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Acetabulum↗
PubMed2003

Comparison of synthetic hydroxyapatite and porous polyethylene implants in eviscerated rabbit eyes.

PURPOSE: Synthetic hydroxyapatite and porous polyethylene (Polipore) spheres were placed in rabbits' eviscerated cavities to evaluate tissue reaction and volume maintenance. METHODS: Fifty-six Norfolk albino rabbits underwent unilateral evisceration and implantation of synthetic hydroxyapatite (H group, 28 animals) or porous polyethylene spheres (P group, 28 animals). Postoperative reactions, animal behavior, and socket conditions were monitored. Light microscopy and morphometric evaluation with statistical analysis of the exenterated orbits were performed at 7, 15, 30, 60, 90, 120, and 180 days. Scanning electron microscopy was appraised 7, 60, and 180 days after surgery. RESULTS: Two animals from the H group and 1 from the P group had extrusion 7 days after surgery. Throughout the experimental period, the synthetic hydroxyapatite caused more inflammation than the porous polyethylene material. Ingrowth in the sphere occurred 7 to 15 days after the surgery in both groups, and the tissue reaction became denser at approximately 60 to 90 days, when bony metaplasia began in the H group. Volume maintenance was better in the P group and with a smaller pseudocapsule surrounding the implanted sphere than in the H group. CONCLUSIONS: Clinical findings demonstrated mild inflammation inside the sphere and in the pseudocapsule surrounding it and better cavity volume maintenance in the P group animals. The authors consider porous polyethylene a more suitable material than synthetic hydroxyapatite for use in anophthalmic cavity reconstruction.

Animals↗
PubMed2003

Bovine pericardium versus homologous sclera as a wrapping for hydroxyapatite orbital implants.

PURPOSE: To report our experience with bovine pericardium as a wrapping material for hydroxyapatite orbital implants after enucleation and to compare the exposure rates of the implants wrapped with bovine pericardium versus donor sclera. METHODS: We retrospectively reviewed the records of all patients who received bovine pericardium-wrapped or donor sclera-wrapped hydroxyapatite implant after primary enucleation between March 1995 and December 2001. RESULTS: Of the 26 patients who received donor sclera-wrapped implants after enucleation, 1 (3.8%) had implant exposure. Of the 26 patients who received bovine pericardium-wrapped implants after enucleation, 6 (23%) had implant exposure. The incidence of implant exposure with the use bovine pericardium wrapping material was found to be significantly higher than with sclera (P = 0.05). Six of the 7 implant exposures were noted in the first 6 months after placement of the orbital implant. Five of the 6 exposed bovine pericardium-wrapped hydroxyapatite implants were associated with socket infection. The case of exposure of the sclera-wrapped implant was treated conservatively by observation. Six patients who had exposure of bovine pericardium-wrapped implants required multiple repairs because of recurrent exposures. Four of these patients eventually required removal of the implant. CONCLUSIONS: Despite the advantages of using bovine pericardium as a wrapping material for hydroxyapatite orbital implants, we observed a significantly higher incidence of exposure with bovine pericardium compared with donor sclera in the early postoperative period. Use of bovine pericardium as a wrapping material for orbital implants should be avoided unless some future modifications of the technique can be developed to prevent such complications.

Adolescent↗
PubMed2005

Chronic inflammation from polycarbonate motility peg inhibits osteogenesis in a human hydroxyapatite orbital implant.

The histologic findings of a pegged hydroxyapatite orbital implant removed due to chronic inflammation and pain are described. A 44-year-old woman underwent explantation of a hydroxyapatite sphere and polycarbonate motility peg due to chronic redness, swelling, discharge, and pain. Histology revealed complete fibrovascularization of the implant, with approximately 90% ossification. No bone marrow was identified. Histologic sections revealed fibrous connective tissue at the periphery of a sclerotic bony mass with a granulomatous inflammatory infiltrate at the motility peg aperture. There were no bacterial, mycobacterial, or fungal organisms identified histologically or by culture. Consistent with previous reports, hydroxyapatite orbital implants are amenable to fibrovascular ingrowth and bony transformation. The presence of a granulomatous inflammatory reaction around the polycarbonate motility peg in this case may have prevented complete osseous transformation of the hydroxyapatite implant.

Adult↗
PubMedDate not supplied

Mersilene mesh versus sclera in wrapping hydroxyapatite orbital implants.

PURPOSE: To compare Mersilene mesh versus sclera in wrapping hydroxyapatite orbital implants used in primary enucleation. METHODS: In a prospective, randomized, interventional comparative case series, 60 eyes from 60 consecutive patients were included and randomly allocated for primary enucleation and either Mersilene mesh-wrapped hydroxyapatite (MHA) orbital implant (30 cases, 50%) or sclera-wrapped hydroxyapatite (SHA) orbital implant (30 cases, 50%) under general anesthesia. Complete socket examination was performed at 1 week, 1 month, and then every 3 months after surgery. RESULTS: Mean age was not significantly different (P = 0.08) between patients with MHA (36.43 years) and SHA (28.50 years) orbital implants. The most common cause of enucleation was trauma in both groups (P = 0.09). Patients with MHA had significantly (P = 0.005) longer follow-up time (mean, 11.40 months) than those with SHA (mean, 9.40 months). No exposure was found at last follow-up in the MHA group, but one patient in the SHA group had a small exposure (1 x 1 mm) 1 month after surgery that was conservatively treated. There were no significant postoperative soft tissue complications in either group. CONCLUSIONS: Sclera and Mersilene mesh could be used as a wrapping material for hydroxyapatite orbital implants without significant complications. Absence of disease transmission, low cost, and availability are the main advantages of Mersilene mesh.

Adolescent↗
PubMed2006

Delayed extrusion of hydroxyapatite after transpetrosal reconstruction.

OBJECTIVES: : To review the long-term results of hydroxyapatite closure of transpetrosal defects. STUDY DESIGN: : Retrospective chart review. METHODS: : One hundred seventy-seven patients were followed for more than 5 years. After surgical management by way of transpetrosal routes, hydroxyapatite was placed after medial wound closure with abdominal fat and before a three-layered lateral soft tissue closure. RESULTS: : Among this group of patients, three (1.7%) cerebrospinal fluid (CSF) leaks were encountered. None of these required re-operation. Delayed extrusion of hydroxyapatite with concomitant superficial wound infections have occurred in seven (4%) patients. All required operative re-intervention. CONCLUSIONS: : Hydroxyapatite has proven to be an effective material in the closure of skull base defects. Nevertheless, delayed extrusion of this agent can occur, resulting in the potential for morbidity and the need for operative re-intervention.

Adipose Tissue↗
PubMed2004

An ultrastructural study of cellular response to variation in porosity in phase-pure hydroxyapatite.

Hydroxyapatite has been shown to be biocompatible and bioactive. Incorporation of porosity has been shown to enhance osteointegration; however, difficulty in controlling the extent and type of porosity has limited investigation into determining the role of both macro- and microporosity. The current investigation reports on the synthesis of four types of phase-pure hydroxyapatite with varying levels of porosity (HA1-HA4), and with defined levels of macro- and microporosities. Transmission electron microscopy was used to evaluate qualitatively the effect of these two parameters on cell-material interactions following a 30-day incubation period. Biological mineralization was observed within vesicles and the needle-like minerals were confirmed as hydroxyapatite using X-ray microanalysis. This demonstrated the suitability of primary human osteoblast-like cells as a tool to assess the extent of mineralization. Furthermore, internalization of hydroxyapatite particles was observed. Our findings show that the variation in macro- and microporosity does not affect the extent of cell-material interaction, with collagen synthesis evident in all samples.

Cell Communication↗
PubMed1996

Inhibition of adherence of Actinomyces naeslundii (Actinomyces viscosus) T14V-J1 to saliva-treated hydroxyapatite by a monoclonal antibody to type 1 fimbriae.

A monoclonal antibody to Actinomyces naeslundii (A. viscosus) T14V-J1 type 1 fimbriae, capable of inhibiting the adherence of this bacterium to salivary proline-rich protein-treated hydroxyapatite, was generated by immunization of SWR mice with A. naeslundii 55-19, a strain derived from T14V-J1 that possess only type 1 fimbriae. Supernatants of hybridomas were screened for reactivity with purified type 1 fimbriae. An IgG monoclonal antibody, 86-49E, blocked the adsorption of the parent strain to proline-rich protein-treated hydroxyapatite by 77% with 1.0 microgram/ml of the monoclonal antibody; the Fab fragment derived from this monoclonal antibody inhibited adherence by 38% at the same concentration. Similarly, the adherence of strain 55-19 was inhibited by 100% and 64% to proline-rich protein-treated hydroxyapatite with 1.0 micrograms/ml of IgG and Fab fragments respectively. Control monoclonal antibody to the subunit of type 1 fimbriae, as well as to Actinobacillus actinomycetemcomitans caused only minimal adherence inhibition. Monoclonal antibody 86-49E also agglutinated both type 1 fimbriae-bearing strains of A. naeslundii T14V-J1 and 55-19 but not strains 59-51 and 147, which lack type 1 fimbriae. Further confirmation of the specificity of monoclonal antibody 86-49E was obtained using these fimbria-deficient mutant strains in an enzyme-linked immunosorbent assay, with the monoclonal antibody binding only to strains possessing type 1 fimbriae. Immunogold labeling in conjunction with electron microscopy suggested binding of monoclonal antibody 86-49E occurring near the distal end of the fimbriae. In contrast, when a monoclonal antibody specific for the type 1 fimbrial subunit but not capable of adherence inhibition was used together with 86-49E in double-labeling experiments, extensive labeling of the fimbriae by the subunit antibody was noted. These data suggest that a monoclonal antibody specific for the type 1 fimbriae of A. naeslundii that is capable of binding to a discrete site on the fimbriae has the capacity to inhibit the adsorption of this organism to saliva-treated hydroxyapatite.

Actinomyces viscosus↗