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PubMed2001

Combined implantation of particulate dentine, plaster of Paris, and a bone xenograft (Bio-Oss) for bone regeneration in rats.

UNLABELLED: The purpose of this study is to assess the combination of particulate dentine and plaster as bone substitute material in calvarial bone defects in rats, and to compare it with a bone xenograft (Bio-Oss). MATERIAL AND METHODS: Forty rats were assigned randomly to five groups and each group was further divided into two subgroups, 8 and 16 weeks after implantation. The defect was filled with different graft materials in each group: Group 1, defects were filled with particulate dentine and plaster using a 2:1 ratio; Group 2, defects were filled with particulate dentine; plaster, and Bio-Oss using a 2:1:1 ratio; Group 3, defects were filled with plaster and Bio-Oss using a 1:1 ratio; Group 4, defects were filled with Bio-Oss only; and Group 5, untreated control defects. Histological sections and histomorphometric analysis of defects were obtained at 8 and 16 weeks postoperatively. RESULTS: New bone formation was highest in Group 4, followed by Group 3, than Group 2, Group 1, and finally the control group. CONCLUSION: The combination of particulate dentine and plaster is an alternative bone substitute, although it is less effective than Bio-Oss.

Analysis of Variance↗
PubMed2006

Filling a cervical spine cage with local autograft: change of bone density and assessment of bony fusion.

To date, it remains debatable whether cervical spine fusion cages should be filled with any kind of bone or bone substitute. Using a bone substitute would produce additional costs, using an autologous bone graft from the iliac crest would make the use of the cage at least questionable. As an alternative, cortical and subcortical bone from the anterior osteophytes of the segment in which the disc has been removed could be used to fill the cage: higher costs and complications at the iliac crest could both be avoided and the cage could be filled. However, the fate of these bone chips made from the anterior osteophytes is unclear as well as whether fusion will occur using this technique. The objective of the current study was to investigate possible changes in the bone density of this local autograft in the cage within the first 12 months after surgery by means of computed tomography. A second objective was to assess segmental bony fusion using this technique. 21 patients, suffering from degenerative disc disease of the cervical spine, were included into this prospective study. They all underwent anterior decompression, cage insertion and plate stabilisation. The cage (Rabea, Signus Medizintechnik, Alzenau, Germany), was filled with bone chips made from the anterior osteophytes of the segment that underwent discectomy. On the third day after surgery as well as three, six and 12 months after surgery, an axial computed tomography scan through the cage was taken and density within the apertures of the cage was measured in a standardised manner. Flexion-extension lateral radiographs were taken to investigate segmental fusion. Statistical significance was assumed to be at a 95 % level of significance. 23 cages were implanted. The mean value of the bone density obtained by computed tomography was 505 (+/- 119) HU on day three, 635 (+/- 156) HU after three months, 769 (+/- 162) HU after six months, and 814 (+/- 198) after 12 months. There was a significant difference when the values after 12 months were compared to those obtained after three days (p < 0.001) and after three months (p = 0.004). Bony fusion was seen in 21 out of 23 segments (91.3 %) after 12 months. It may be concluded that this technique could be an alternative to the current treatment options.

Bone Density↗
PubMed2001

The use of a surgical grade calcium sulfate as a bone graft substitute: results of a multicenter trial.

In a prospective, nonrandomized, multicenter study, 109 patients with bone defects were treated with a surgical grade calcium sulfate preparation as a bone graft substitute. The calcium sulfate pellets were used in place of morselized cancellous bone graft for the treatment of patients with bone defects who usually would require grafting secondary to trauma, periprosthetic bone loss, tumor, or fusion. The calcium sulfate was used alone or mixed with other materials such as bone marrow aspirate, demineralized bone matrix, or autograft. The defects that were treated were contained and were not necessary for the stability of the bony structure. Radiographic and clinical data were collected at predetermined intervals for 12 months. At 6 months postoperatively, radiographic results for all patients showed that 99% of the calcium sulfate had been resorbed and 88% of the defect was filled with trabeculated bone. There were 13 complications; however, only four (3.6%) were attributable to the product. The results of a subgroup of 46 patients with benign bone lesions treated in the same manner are identical to the results of the overall study population. Surgical grade calcium sulfate pellets are considered a convenient, safe, and readily available bone graft substitute that yield consistent successful results.

Absorbable Implants↗
PubMed1999

Coralline bone graft substitutes.

Coralline porous ceramics are biocompatible and osteoconductive implants. They have proven to be effective as bone graft substitutes in large animal models and in humans. Bone and supporting soft tissue grow into and throughout their porosity if the implant is placed in direct apposition to viable bone and the interfaces are stabilized. The bone within the implant remodels in response to Wolff's law. Both the implant properties (chemistry and porosity) and the biologic environment modulate the rate of implant resorption. Composite technology with resorbable polymers can improve the mechanical properties of these ceramics.

Absorbable Implants↗
PubMed2003

Enhanced bioactivity of a poly(propylene fumarate) bone graft substitute by augmentation with nano-hydroxyapatite.

The bioactivity of a nano-hydroxyapatite-augmented, bioresorbable bone graft substitute made from the unsaturated polyester, poly(propylene fumarate), was analyzed by evaluating biocompatibility and osteointegration of implants placed into a rat tibial defect. Three groups of eight animals each were evaluated by grouting bone graft substitutes into 3-mm holes that were made into the anteromedial tibial metaphysis of rats. Thus, a total of 24 animals was included in this study. Two different formulations varying as to the type of hydroxyapatite were used: Group 1 - nano-hydroxyapatite, Group 2 - micron-hydroxyapatite, with a Group 3 control defect remaining unfilled. Animals of each of the three groups were sacrificed in groups of eight at postoperative week three. Histologic analysis revealed best superior biocompatibility and osteointegration of bone graft substitutes when nanohydroxyapatite was employed. At three weeks, there was more reactive new bone formation in this group when compared to the micron-hydroxyapatite group. The control group showed incomplete closure of the defect. This study suggested that nano-hydroxyapatite may improve upon the bioactivity of bone implant and repair materials. The model scaffold used in this study, poly(propylene fumarate), appeared to provide an osteoconductive pathway by which bone will grow in faster. Clinical implications of the use potential advantages of nano-hydroxyapatite on bone repair and orthopaedic implant design are discussed.

Absorbable Implants↗
PubMedDate not supplied

Evaluation of processed bovine cancellous bone matrix seeded with syngenic osteoblasts in a critical size calvarial defect rat model.

INTRODUCTION: Biologic bone substitutes may offer alternatives to bone grafting procedures. The aim of this study was to evaluate a preformed bone substitute based on processed bovine cancellous bone (PBCB) with or without osteogenic cells in a critical size calvarial defect rat model. METHODS: Discs of PBCB (Tutobone) were seeded with second passage fibrin gel-immobilized syngenic osteoblasts (group A, n = 40). Cell-free matrices (group B, n = 28) and untreated defects (group C; n=28) served as controls. Specimens were explanted between day 0 and 4 months after implantation and were subjected to histological and morphometric evaluation. RESULTS: At 1 month, bone formation was limited to small peripheral areas. At 2 and 4 months, significant bone formation, matrix resorption as well as integration of the implants was evident in groups A and B. In group C no significant regeneration of the defects was observed. Morphometric analysis did not disclose differences in bone formation in matrices from groups A and B. Carboxyfluorescine-Diacetate-Succinimidylester (CFDA) labeling demonstrated low survival rates of transplanted cells. DISCUSSION: Osteoblasts seeded into PBCB matrix display a differentiated phenotype following a 14 days cell culture period. Lack of initial vascularization may explain the absence of added osteogenicity in constructs from group A in comparison to group B. PBCB is well integrated and represents even without osteogenic cells a promising biomaterial for reconstruction of critical size calvarial bone defects.

Animals↗
PubMed2000

Bioresorbable bone graft substitutes of different osteoconductivities: a histologic evaluation of osteointegration of poly(propylene glycol-co-fumaric acid)-based cement implants in rats.

Bioresorbable bone graft substitutes may significantly reduce the disadvantages associated with autografts, allografts and other synthetic materials currently used in bone graft procedures. We investigated the biocompatibility and osteointegration of a bioresorbable bone graft substitute made from the unsaturated polyester poly(propylene-glycol-co-fumaric acid), or simply poly(propylene fumarate), PPF, which is crosslinked in the presence of soluble and insoluble calcium filler salts. Four sets of animals each having three groups of 8 were evaluated by grouting bone graft substitutes of varying compositions into 3-mm holes that were made into the anteromedial tibial metaphysis of rats. Four different formulations varying as to the type of soluble salt filler employed were used: set 1--calcium acetate, set 2--calcium gluconate, set 3--calcium propionate, and set 4--control with hydroxapatite, HA, only. Animals of each of the three sets were sacrificed in groups of 8 at postoperative week 1, 3, and 7. Histologic analysis revealed that in vivo biocompatibility and osteointegration of bone graft substitutes was optimal when calcium acetate was employed as a soluble salt filler. Other formulations demonstrated implant surface erosion and disintegration which was ultimately accompanied by an inflammatory response. This study suggested that PPF-based bone graft substitutes can be designed to provide an osteoconductive pathway by which bone will grow in faster because of its capacity to develop controlled porosities in vivo. Immediate applicability of this bone graft substitute, the porosity of which can be tailored for the reconstruction of defects of varying size and quality of the recipient bed, is to defects caused by surgical debridement of infections, previous surgery, tumor removal, trauma, implant revisions and joint fusion. Clinical implications of the relation between developing porosity, resulting osteoconduction, and bone repair in vivo are discussed.

Animals↗
PubMed2005

Histomorphometric and densitometric evaluation of the effects of platelet-rich plasma on the remodeling of beta-tricalcium phosphate in beagle dogs.

Countless possibilities are available in maxillofacial surgery for the filling of bone defects. The best bone substitute known at present is osteogenic autogenous bone, but its use is accompanied by numerous disadvantages. The question has arisen of whether results attained with osteoconductive bone substitutes approach those achieved by the transplantation of autogenous bone. The aims of the investigation were to measure the effects in animal experiments of the growth factors to be found in the platelets on the rate of remodeling of beta-tricalcium phosphate, and on the quality of the new bone formed. Defects formed in the mandibles of 10 Beagle dogs were filled with beta-tricalcium phosphate or with a mixture of beta-tricalcium phosphate and platelet-rich plasma obtained from autogenous blood. The quality of the hard tissue formed and the effect of the platelet-rich plasma were examined by statistical analysis of the densitometric results obtained after 6 weeks and the histological and histomorphometric results obtained after 12 weeks. The densitometric study revealed that the bone formation was significantly more effective when platelet-rich plasma was used; at this stage, histomorphometric evaluation did not indicate a significant difference. After 12 weeks, however, the histomorphometric study demonstrated a significant difference in favor of the bone substitute used together with platelet-rich plasma. The results strongly suggest that use of the platelet-rich plasma suspension accelerates the remodeling of beta-tricalcium phosphate and leads to the formation of hard tissue with a quality similar to that of the autogenous bone.

Absorptiometry, Photon↗
PubMed1984

A coralline hydroxyapatite bone graft substitute. Preliminary report.

Experimental histologic and biomechanical studies were performed in 52 dogs by use of a bone substitute composed of hydroxyapatite converted from sea coral calcite. The results demonstrate some potentially useful practical applications. The material was totally incorporated in bone. Although initially too weak to tolerate physiologic stresses, once incorporated it becomes almost as strong as the native bone. Clinical experience with internal fixation of fractures with hydroxyapatite in 18 patients is encouraging.

Adult↗
PubMed2000

Bovine calcined bone for the repair of radial defect in a rabbit model.

In order to investigate the bovine calcined bone's ability of repairing segmental bone defect and seek a new artificial bone substitute material, the bovine calcined bone (450 degrees C, 32 h) was implanted into the 10-mm middle radial defect of rabbits with tricalcium phosphate ceramics as the control. By using the methods of histology, radiology and biomechanics their osteogenic ability were measured. It was found that the bovine calcined bone's ability of repairing bone defect was better than that of tricalcium phosphate ceramics. The histological Nilsson's scores at 3rd, 5th, 9th week after operation were significantly increased (P < 0.01). At 12th week after operation the bending strength of radius in experimental group was much higher than that of control group and turned normal. It was suggested that bovine calcined bone is an ideal artificial bone substitute material with good ability of repairing segmental bone defect and some degree of mechanical strength.

Animals↗
PubMed2004

Mediation of bone ingrowth in porous hydroxyapatite bone graft substitutes.

Previous investigations have shown that both the early biological response and the mechanical properties of a porous hydroxyapatite bone graft substitute are highly sensitive to its pore structure. The objective of this study was to evaluate whether the pore structure continued to influence bone integration in the medium to long term. Two screened batches of porous hydroxyapatite (PHA) designated as batch A and batch B, with porosities of approximately 60 and 80%, respectively, were selected for this study and implanted for periods of 5, 13, and 26 weeks into the lower femur of New Zealand White rabbits. Histomorphometric analysis of the absolute volume of bone ingrowth within batch A and B implants from 5 to 26 weeks showed that the absolute volume of bone ingrowth was consistently lower in batch A (10-21%), compared to batch B implants (24-31%). However, when the volume of bone ingrowth was normalised for the available pore space, this difference was reduced (23-47% and 32-42% for batches A and B, respectively). These observations suggest that differences in the volume of bone ingrowth initially depended on pore interconnectivity rather than pore size, whereas the volume or morphology of the PHA influenced the volume and morphology of bone ingrowth at later time points. Compression testing showed that bone ingrowth had a strong reinforcing effect on PHA bone graft substitutes, and a strong correlation was identified between mechanical properties and the absolute volume of ingrowth for both batches A and B. Furthermore, at 13 and 26 weeks, there was no significant variation in the ultimate compressive strength of integrated batch A and B implants. This similarity in ultimate mechanical properties indicated that the absolute volume of ingrowth may be mediated by the PHA structure through its impact on the dynamics of the local biomechanical environment. The results of push-out testing showed that fixation of PHA bone graft substitutes was independent of density within the range studied, with no significant difference in the interfacial shear stress between batches A and B at each time point throughout the study.

Animals↗
PubMed1996

[Defect fractures of the tibia--various forms of bone replacement].

Different bone substitutes exist for reconstruction of segmental tibial bone defects. The choice of bone substitute is limited by the quality of the surrounding tissue and the size of the bone defect. Especially in large bone defects, the freely or microvascularly transferred autogenic graft should be preferred. Allogenic transplants or artificial bone substitutes, such as spongy calcium phosphate materials, are suitable only for implantation in smaller, well-vascularized bone defects or as an additional procedure in large bone defects. In infected cases, allogenic and artificial, especially slowly resorbable implants, have to be avoided. The prerequisite for defect reconstruction is stable internal fixation.

Bone Substitutes↗
PubMed2006

Bone healing and graft resorption of autograft, anorganic bovine bone and beta-tricalcium phosphate. A histologic and histomorphometric study in the mandibles of minipigs.

OBJECTIVE: The purpose was to qualitatively and quantitatively compare the bone formation and graft resorption of two different bone substitutes used in both orthopedic and oral surgery, with autogenous bone as a positive control. MATERIALS AND METHODS: Three standardized bone defects were prepared in both mandibular angles of 12 adult minipigs. The defects were grafted with either autograft, anorganic bovine bone (ABB), or synthetic beta-tricalcium phosphate (beta-TCP). Sacrifice was performed after 1, 2, 4, and 8 weeks for histologic and histomorphometric analysis. RESULTS: At 2 weeks, more new bone formation was seen in defects filled with autograft than with ABB (P approximately 0.0005) and beta-TCP (P approximately 0.002). After 4 weeks, there was no significant difference between beta-TCP and the two other materials. Defects grafted with ABB still exhibited less bone formation as compared with autograft (P approximately 0.004). At 8 weeks, more bone formation was observed in defects grafted with autograft (P approximately 0.003) and beta-TCP (P approximately 0.00004) than with ABB. No difference could be demonstrated between beta-TCP and autograft. beta-TCP resorbed almost completely over 8 weeks, whereas ABB remained stable. CONCLUSION: Both bone substitutes seemed to decelerate bone regeneration in the early healing phase as compared with autograft. All defects ultimately regenerated with newly formed bone and a developing bone marrow. The grafting materials showed complete osseous integration. Both bone substitutes may have a place in reconstructive surgery where different clinical indications require differences in biodegradability.

Animals↗
PubMed2006

Instrumented fusion of thoracolumbar fracture with type I mineralized collagen matrix combined with autogenous bone marrow as a bone graft substitute: a four-case report.

In order to avoid the morbidity from autogenous bone harvesting, bone graft substitutes are being used more frequently in spinal surgery. There is indirect radiological evidence that bone graft substitutes are efficacious in humans. The purpose of this four-case study was to visually, manually, and histologically assess the quality of a fusion mass produced by a collagen hydroxyapatite scaffold impregnated with autologous bone marrow aspirate for posterolateral fusion. Four patients sustained an acute thoracolumbar fracture and were treated by short posterior segment fusion using the AO fixateur interne. Autologous bone marrow (iliac crest) impregnated hydroxyapatite-collagen scaffold was laid on the decorticated posterior elements. Routine implant removal was performed after a mean of 15.3 months (12-20). During this second surgery, fusion mass was assessed visually and manually. A bone biopsy was sent for histological analysis of all four cases. Fusion was confirmed in all four patients intraoperatively and sagittal stress testing confirmed mechanical adequacy of the fusion mass. Three out of the four (cases 2-4) had their implants removed between 12 and 15 months after the index surgery. All their histological cuts showed evidence of newly formed bone and presence of active membranous and/or enchondral ossification foci. The last patient (case 1) underwent implant removal at 20 months and his histological cuts showed mature bone, but no active ossification foci. This four-case report suggests that the fusion mass produced by a mineralized collagen matrix graft soaked in aspirated bone marrow is histologically and mechanically adequate in a thoracolumbar fracture model. A larger patient series and/or randomized controlled studies are warranted to confirm these initial results.

Adult↗
PubMed2004

Assessment of bone graft substitutes in autopsy implant retrievals of the acetabulum in total hip arthroplasty.

Two autopsy retrievals of acetabular reconstruction with different bone graft substitutes were analyzed. One patient underwent surgery with hydroxyapatite (HA) granules, and the other with demineralized bone chips. Incorporation occurred with the biomaterial bone-graft substitute HA primarily in the superior part of the acetabulum, where the HA was in contact with host cortical bone. No bony union occurred with the demineralized bone chips because of motion and migration of the acetabular cup. No bone incorporation of either bone-graft substitute was observed in the medial wall defects in both patients. There were two important findings: (1) the 3- to 8-mm depth and 70% to 75% surface of union of the HA bone graft substitute to host cortical bone was the same as seen with morselized, fresh-frozen bone graft; and (2) union of graft material to host bone was dependent on secure fixation of the acetabular construct.

Acetabulum↗
PubMed2003

A resorbable porous ceramic composite bone graft substitute in a rabbit metaphyseal defect model.

The success of converted corals as a bone graft substitute relies on a complex sequence of events of vascular ingrowth, differentiation of osteoprogenitor cells, bone remodeling and graft resorption occurring together with host bone ingrowth into and onto the porous coralline microstructure or voids left behind during resorption. This study examined the resorption rates and bone infiltration into a family of resorbable porous ceramic placed bilaterally in critical sized defects in the tibial metaphyseal-diaphyseal of rabbits. The ceramics are made resorbable by partially converting the calcium carbonate of corals to form a hydroxyapatite (HA) layer on all surfaces. Attempts have been made to control the resorption rate of the implant by varying the HA thickness. New bone was observed at the periosteal and endosteal cortices, which flowed into the centre of the defect supporting the osteoconductive nature of partially converted corals. The combination of an HA layer and calcium carbonate core provides a composite bone graft substitute for new tissue integration. The HA-calcium carbonate composite demonstrated an initial resorption of the inner calcium carbonate phase but the overall implant resorption and bone ingrowth behaviour did not differ with HA thickness.

Animals↗
PubMed1994

Morbidity after anterior cervical decompression and fusion. The influence of the donor site on recovery, and the results of a trial of surgibone compared to autologous bone.

The Cloward procedure is a routine approach to decompress and fuse the cervical spine. This paper looks at two aspects of the operation. Firstly the morbidity due to the hip wound is assessed, and alternatives to the use of autologous bone graft discussed. Secondly one Neurosurgical Unit's experience in the use of surgibone--an animal bone substitute harvested from steers and fashioned in dowels--is described. In this trial it was not found to be a satisfactory substitute to autologous bone.

Adult↗