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PubMedDate not supplied

The use of nanocrystalline hydroxyapatite for the reconstruction of calcaneal fractures: Preliminary results.

The purpose of this investigation was to evaluate the feasibility of a nanocrystalline hydroxyapatite compound in the treatment of calcaneal fractures with osseous defects after reduction. The study included 21 patients, representing 24 closed intraarticular calcaneus fractures with large defects remaining after operative reduction. All cases were supplemented with the hydroxyapatite bone substitute and stabilized with a calcaneal honeycomb plate. Radiographs were taken at 6 weeks, 12 weeks, 6 months, and 1 year postoperatively, with specific attention given to measurement of Gissane's angle, Böhler's angle, and calcaneal height. A postoperative subjective and objective evaluation of the fracture, using the Creighton Nebraska Health Foundation scale, was performed 1 year postoperatively. Böhler's angle improved from a mean 8.6 +/- 5.3 degrees preoperatively to an immediate postoperative mean result of 31.5 +/- 6.5 degrees and 27.7 +/- 8.6 1 year postoperatively. The mean Creighton-Nebraska functional score was 86 +/- 10 at the 1-year follow-up evaluation. These results suggest that open reduction with plate fixation combined with nanocrystalline hydroxyapatite augmentation presents a good and reliable surgical technique for treatment of calcaneus fractures.

Adult↗
PubMed2000

Osseous integration of bovine hydroxyapatite ceramic in metaphyseal bone defects of the distal radius.

Hydroxyapatite ceramic made of bovine spongiosa was used as structural support material in a prospective study to correct bone defects experienced after reduction in distal radius fractures. The study took place over a 3-year period (1992-1999) and comprised 14 patients. Osseous integration was analyzed via biopsies and magnetic resonance imaging. Long-term follow-up monitoring involving magnetic resonance imaging in 13 of the 14 patients showed fibrovascular growth within incorporated hydroxyapatite material. Osseous integration was demonstrated in magnetic resonance images by gadolinium uptake and by the presence of osteoid layers and endothelialized vessels. Hydroxyapatite ceramic offers a biologically acceptable alternative to autologous bone when augmenting distal radius fracture fixation.

Adult↗
PubMed2002

A prospective 1-year clinical and radiographic study of implants placed after maxillary sinus floor augmentation with bovine hydroxyapatite and autogenous bone.

PURPOSE: The purposes of this study were 1) to evaluate the survival rate of implants placed in maxillary sinuses augmented with bovine hydroxyapatite and autogenous bone 6 months before implant surgery and 2) to estimate dimensional changes of the bone graft with time using a new radiographic method. PATIENTS AND METHODS: Thirty maxillary sinuses in 20 consecutive patients with severe resorption (mean, 3.8 mm of remaining alveolar bone) were augmented with a mixture of 80% bovine hydroxyapatite and 20% autogenous bone mixed with fibrin glue to enable the placement of screw-shaped dental implants. After 6 months of primary healing, 108 implants were placed and followed with clinical and radiographic examinations during the first year of loading. Measurements of changes in height, width, and length of the grafted material were made on tomographic Scanora (Soredex Orion Corporation Ltd, Helsinki, Finland) and panoramic radiographs taken 3 and 12 months after grafting and after 1 year of bridge loading. RESULTS: Ten implants in 6 patients were lost during the study (9 before loading and 1 after 1 year of functional loading), for a survival rate of 90.7%. All patients received fixed restorations, and the bridge survival rate was 100% after 1 year of loading. Small (<10%) but statistically significant dimensional changes in the grafted material were seen during the study period. CONCLUSIONS: Acceptable short-term results can be obtained with implants placed after the use of bovine hydroxyapatite and autogenous bone for maxillary sinus floor augmentation. These grafts show good resistance to resorption.

Aged↗
PubMed2001

Heterotopic ossification after uncemented hydroxyapatite-coated primary total hip arthroplasty.

A total of 134 patients who had a cementless hydroxyapatite-coated total hip arthroplasty (THA) and had no recognized risk factors for heterotopic ossification (HO) were reviewed retrospectively. The average follow-up period was 83 months. Pharmacologic or radiotherapeutic prophylaxis against HO was not used. HO was seen in 90 (67.2%) of the 134 patients reviewed. HO was rated as Brooker class I in 68 (50.7%) patients, class II in 17 (12.7%) patients, class III in 3 (2.2%) patients, and class IV in 2 (1.5%) patients. The average Merle d' Aubigne score in patients with mild forms of HO (Brooker classes I and II) was 16 compared with 13.2 in patients with severe HO (Brooker classes III and IV). A statistically significant negative correlation was found between the presence of HO and the postoperative hip score. Based on our study findings and on a comparison with data in the literature, hydroxyapatite-coated cementless THA alone does not seem to increase the likelihood of HO over other types of THA. The presence of a hydroxyapatite coating does not result in more class III or IV HO, which are the only classes of HO with real clinical significance. Fear of HO should not be a factor in the choice of fixation for THA.

Adult↗
PubMed2000

Hydroxyapatite cement: an alternative for craniofacial skeletal contour refinements.

Hydroxyapatite cement is a calcium phosphate preparation composed of tetracalcium phosphate and dicalcium phosphate anhydrous powders. When mixed with water it isothermically forms a paste which can easily be shaped intraoperatively. This mixture sets in approximately 15-20 min and converts into water insoluble, nonceramic, microporous hydroxyapatite in 4 h. This biomaterial was used to correct either congenital or traumatic craniofacial contour irregularities or deficiencies in 20 patients. On follow-up there was only one patient who required repeat surgery for further correction, there were no other complications. The good cosmetic results, the ease of operation, the pliability of the cement paste allowing precise moulding during application, the short operation time and the avoidance of a donor site makes hydroxyapatite cement an attractive material for treating craniofacial contour defects. Careful long term follow-up is necessary to establish its safety and reliability.

Adolescent↗
PubMed2000

The use of an in situ curing hydroxyapatite cement as an alternative to bone graft following removal of enchondroma of the hand.

Following curettage of enchondromata of the phalanges we filled the resultant bone cavity with hydroxyapatite cement in eight patients to avoid cancellous bone grafting. This material differs significantly from the ceramic hydroxyapatite commonly used in clinical practice. It is produced by the combination of two calcium phosphates which, in the presence of water, form a paste that cures to a solid implant with a microporous structure. Like ceramic hydroxyapatite, this cement is highly biocompatible and does not provoke a foreign body giant cell reaction, a sustained inflammatory response or a toxic reaction. We performed a prospective study with X-rays and clinical assessment up to 1 year after the operation. There were no complications, and all patients regained full function of the hand.

Adult↗
PubMed2000

Applications of fast-setting hydroxyapatite cement: cranioplasty.

A variety of autogenous and synthetic materials have been used to repair cranial defects resulting from traumatic and iatrogenic causes. In theory, the ideal material should be readily available and safe. It should adequately protect the underlying central nervous system, resist cerebrospinal fluid fistula formation, and be easily contoured. One promising synthetic biomaterial that has been used for cranioplasty is hydroxyapatite cement. This biomaterial has successfully restored cranial contour in most patients in whom it has been used; however, difficulties have arisen because of the material's prolonged water solubility. When exposed to cerebrospinal fluid or blood, inadequate setting of the cement occurs, resulting in loss of its structural integrity. This problem can be alleviated with the use of fast-setting hydroxyapatite cement, which hardens 6 to 12 times faster than the traditional cement. We present, to the best of our knowledge, the first series of the use of this material in 21 patients requiring cranioplasty. The advantages and limitations of fast-setting hydroxyapatite cement will be discussed.

Adult↗
PubMed2002

Histologic evaluation of a hydroxyapatite onlay bone graft retrieved after 9 years: a clinical report.

Because of the limited observations of published studies, the condition of hydroxyapatite after a long period of intraoral function remains a concern. This clinical report describes the histologic evaluation of a 9 year-old hydroxyapatite specimen retrieved from a human subject. The residual hydroxyapatite particles showed no sign of resorption, and tight contact with the surrounding bone was observed.

Alveolar Ridge Augmentation↗
PubMed2001

Hydroxyapatite-coated total hip replacement in Paget's disease: 20 patients followed for 4-8 years.

20 patients, who had had total hip replacements for symptomatic osteoarthrosis secondary to Paget's disease, were followed for a mean of 6 (4-8) years. Proximal hydroxyapatite-coated stems were implanted in all patients. 12 patients received hydroxyapatite-coated, 2 cemented (Muller type) and 6 cementless cups (Morsher type). The mean Harris hip score was 31 (7-40) points preoperatively and 88 (74-100) postoperatively. The radiographic evaluation revealed good stability and fixation using Engh's criteria. One stem subsided early more than 5 mm and then seemed to stabilize. Our findings support the use of hydroxyapatite total hip implants for patients with this disease and osteoarthrosis.

Aged↗
PubMed2006

Cross-species comparison of ectopic bone formation in biphasic calcium phosphate (BCP) and hydroxyapatite (HA) scaffolds.

Material-induced bone formation reported in canine, bovid, suid, and primate species does not often occur in lagomorph or rodent models. In this study, we test biphasic calcium phosphate and hydroxyapatite- induced bone formation in subcutaneous pockets of mice and intramuscular pockets in rats, rabbits, and dogs. All scaffolds are of similar size, and all animals were sacrificed at 90 days post-implantation. In dogs (N = 8), all implants showed bone formation with significantly more bone formed in biphasic calcium phosphates (30 +/- 6%, N = 8) as compared to hydroxyapatite (14 +/- 5%, N = 8) (p = 0.003). Hydroxyapatite implants did not induce bone formation in mice, rats, or rabbits. Biphasic calcium phosphate induced bone in 6 of 8 scaffolds implanted in 4 rabbits and 3 of 16 scaffolds implanted in 16 mice, whereas it did not induce bone formation in any of the 8 rats. The results presented herein suggest that the incidence of material-induced bone formation varies with animal species and is related to the implant material used.

Animals↗
PubMed1997

Pore size of porous hydroxyapatite as the cell-substratum controls BMP-induced osteogenesis.

To elucidate the biochemical mechanism of osteogenesis, the effect of matrix geometry upon the osteogenesis induced by bone morphogenetic protein (BMP) was studied. A series of five porous hydroxyapatites with different pore sizes, 106-212, 212-300, 300-400, 400-500, and 500-600 microns, was prepared. A block (approximately 5 x 5 x 1 mm, 40.0 mg) of each hydroxyapatite ceramics was combined with 4 micrograms of recombinant human BMP-2 and implanted subcutaneously into the back skin of rat. Osteoinductive ability of each implant was estimated by quantifying osteocalcin content and alkaline phosphatase activity in the implant up to 4 wk after implantation. In the ceramics of 106-212 microns, the highest alkaline phosphatase activity was found 2 wk after implantation, and the highest osteocalcin content 4 wk after implantation, consistent with the results observed with particulate porous hydroxyapatite [Kuboki, Y. et al. (1995) Connect. Tissue Res. 32: 219-226]. Comparison of the alkaline phosphatase activities at 2 wk and the osteocalcin contents at 4 wk after implantation revealed that the highest amount of bone was produced in the ceramics implants with pore size of 300-400 microns. In the ceramics with smaller or larger pore sizes, the amount of bone formation decreased as the pore size deviated from 300-400 microns. The results indicated that the optimal pore size for attachment, differentiation and growth of osteoblasts and vascularization is approximately 300-400 microns. This study using chemically identical but geometrically different cell substrata is the first demonstration that a matrix with a certain geometrical size is most favorable for cell differentiation.

Alkaline Phosphatase↗
PubMed1996

Comparison of ossification of demineralized bone, hydroxyapatite, Gelfoam, and bone wax in cranial defect repair.

Demineralized bone allografts in the repair of calvarial defects are compared with other common bone fillers. This study uses a video-digitizing radiographic analysis of calvarial defect ossification to determine calcification of bone defects and its relation to postoperative clinical examination and regional controls. The postoperative clinical results at 3 months demonstrated that bony healing was greatest in bur holes filled with demineralized bone and hydroxyapatite. Radiographic analysis demonstrated calcification of demineralized bone-filled defects compared to bone wax- and Gelfoam-filled regions. Hydroxyapatite granules are radiographically dense, thus not allowing accurate measurement of true bone healing. The results suggest that demineralized bone and hydroxyapatite provide better structural support via bone healing to defined calvarial defects than do Gelfoam and bone wax.

Bone Regeneration↗
PubMed2001

Technique for fixing a temporalis muscle using a titanium plate to the implanted hydroxyapatite ceramics for bone defects.

We devised a technique to fix the temporalis muscle to the transplanted hydroxyapatite implant by using a titanium plate, which is fixed to the hydroxyapatite ceramic implant by screws and achieves good clinical results. The size, shape, and curvature of the hydroxyapatite ceramic implants were determined according to full-scale models fabricated using the laser lithographic modeling method from computed tomography data. A titanium plate was then fixed with screws on the implant before implantation, and then the temporalis muscle was refixed to the holes at both ends of the plate. The application of this technique reduced the hospitalization time and achieved good results esthetically.

Adolescent↗
PubMed1997

Difficulties with hydroxyapatite orbital implants in two patients with dysfunctional levator/superior rectus muscle complex.

Hydroxyapatite orbital implants are recognized for their excellent results in anophthalmos. Few complications are reported in the literature. We implanted hydroxyapatite spheres in two patients with acquired anophthalmos and denervated or nonfunctional levator palpebrae superioris and superior rectus muscles. In both patients, the implant rotated anteriorly, obliterating the superior fornix and causing proptosis. Prosthetic fitting was impeded, necessitating surgical revision in both patients. A hydroxyapatite implant may rotate and migrate anteriorly in the presence of a nonfunctional superior rectus muscle, distorting the conjunctival fornices and causing proptosis. This complication calls into question whether muscle-attached orbital implants should be used in patients with significant rectus muscle weakness.

Adolescent↗
PubMed1999

Repair of orbital floor fractures with hydroxyapatite block scaffolding.

PURPOSE: To determine the efficacy of using a scaffold of hydroxyapatite blocks within the maxillary sinus to treat patients with large orbital floor fractures and secondary vertical globe dystopia. METHODS: Case series of five patients. Hydroxyapatite blocks were stacked within the maxillary antrum to support the reconstructed orbital floor. RESULTS: All patients had good results, though mild residual enophthalmos persisted in three patients. The orbital floor implants and globe positions remained stable during follow-up intervals ranging from 46 to 65 months. No adverse postoperative complications, such as sinusitis, developed. CONCLUSIONS: Hydroxyapatite block scaffolding is a useful alternative to metallic floor implants and autologous bone grafts in the reconstruction of large traumatic orbital floor defects associated with vertical globe dystopia.

Adult↗
PubMed2001

Effects of hyperbaric oxygen therapy on hydroxyapatite orbital implant vascularization in rabbits.

PURPOSE: To deterrmine if hyperbaric oxygen therapy affects the rate of hydroxyapatite orbital implant vascularization in normal rabbit orbits. METHODS: We performed a randomized comparative experimental pilot study involving 6 rabbits. All rabbits were enucleated and implanted with hydroxyapatite orbital spheres. The animals were randomized for enucleation of the right or left eye and for treatment or nontreatment (control) with hyperbaric oxygen. The implants were removed after 3 weeks of treatment and histologically examined for fibrovascular ingrowth, inflammation, and multinucleated giant cells. Each parameter was graded on a numeric scale and analyzed. RESULTS: Hyperbaric oxygen therapy did not increase implant vascularization compared with nontreatment implants. Although treated implants had less central fibrovascular maturity compared with control implants, the difference was not statistically significant (p < 0.055). There was no significant difference in inflammation or the number of multinucleated giant cells between treated and control implants. CONCLUSIONS: In this pilot study, hyperbaric oxygen therapy did not increase hydroxyapatite vascular ingrowth and possibly delayed fibrovascular maturation in normal sockets. Further studies with more subject numbers are needed to confirm these conclusions. The effect of hyperbaric oxygen therapy in vascularly compromised sockets also needs to be determined.

Animals↗
PubMed2001

Natural progress of a bone scan after cementless hydroxyapatite-coated total hip arthroplasty.

To establish the natural progress pattern of postoperative bone uptake, a periprosthetic quantitative technetium-99m methylene diphosphonate scintiscan was done on 80 asymptomatic hips (62 patients) with uncomplicated cementless hydroxyapatite-coated total hip arthroplasties and 20 healthy control hips (10 subjects) without previous surgery. The patients were studied in eight groups at scheduled intervals of 1 to 48 months. There were 10 hips in each group. The measurement of bone uptake in the healthy untreated control group indicated that the uptake ratio in the proximal femur was physiologically higher in the metaphyseal area than in the diaphyseal area and the uptake ratio in the acetabulum appeared to be much higher than that of the proximal femur. In the patient group, the uptake ratio around the femoral stem area and the acetabular cup area showed a statistically significant decrease between 1 and 3 months after surgery and changed little after 3 months. Comparing the result of the patient group with that of the healthy untreated control group, the uptake ratio decreased much faster in the hydroxyapatite-coated metaphyseal zone than in the noncoated diaphyseal zone of the femoral stem area. In the acetabular cup area, the uptake ratio decreased fast, as in the hydroxyapatite-coated metaphyseal zone of the femoral stem area. Based on these clinical results, a quantitative bone scan may be a helpful diagnostic procedure for evaluating postoperative progress when used in conjunction with clinical symptoms and radiologic examinations.

Adult↗
PubMed1999

Use of hydroxyapatite bone cement to prevent cerebrospinal fluid leakage through the frontal sinus: technical report.

OBJECTIVE: To test the efficacy of a simple technique of frontal sinus obliteration during low frontal craniotomy using hydroxyapatite cement instead of more traditional methods, such as pericranial flaps, free muscle or adipose grafts, lumbar drainage, or fibrin glue. METHODS: Eight patients undergoing low frontal craniotomy for intradural surgery had the frontal sinus obliterated by careful removal of mucosa followed by filling of the sinus with hydroxyapatite bone cement. No other adjuncts for preventing cerebrospinal fluid leakage through the sinus were used. RESULTS: At an average follow-up of 9 months, there were no cerebrospinal fluid leaks, infections, instances of resorption, or cosmetic deformities. CONCLUSION: Hydroxyapatite bone cement seems to be a simple and effective method for frontal sinus obliteration and prevention of cerebrospinal fluid leakage.

Aged↗