A radiographical and biomechanical study of demineralized bone matrix implanted into a bone defect of rat femurs with and without bone marrow

Repair of large bone defects represents a challenge to orthopedic surgery since autogenous graft is not available in large amounts. Demineralized bone matrix (DBM) which contains bone morphogenic protein, a potent osteoinductive glycoprotein, and collagen, an osteoconductive matrix, may be an effective substitute for these graft materials. Bone marrow which contains osteoprogenitor cells could potentiate the osteoinductive and osteoconductive properties of demineralized bone matrix. This study tested the ability of demineralized bone matrix with and without bone marrow to bridge large segmental defects, and evaluated the results both radiographically and biomechanically as compared to autogenous (isogeneic) cancellous bone graft. Demineralized bone-matrix segments implanted into a plated femoral segmental defect in rats resulted in firm union in most animals. Bone marrow significantly enhanced bone formation of demineralized bone-matrix implants at an early stage but with time, differences between bone marrow-augmented and bone marrow-deprived demineralized bone implants were no longer demonstrable radiographically and biomechanically. Newly formed bone had about 50% of the strength of the contralateral control bones. Femurs implanted with cancellous bone isografts had similar evidence of absolute union rate, radiographic and mechanical properties as DBM-implanted femurs.     

Bone matrix and marrow versus cancellous bone in rabbit radial defects

Implants of demineralized bone matrix induce new bone formation. In order to estimate the possible clinical usefulness of this phenomenon, autologous cancellous bone grafts were compared with composite grafts of bone matrix and marrow. Cancellous bone from the tuber ischii of the rabbit was transplanted to a preformed radial defect in the same animal. On the opposite side, a similar defect was filled with a mixture of either allogenous or autogenous bone-matrix particles and autogenous bone marrow. After 25 days, calcium 45 was injected intravenously. Three days later the animals were killed. Standardized segments of the rabbit's forearms, containing the middle of the defect, were cut out, ashed, and analyzed for 45Ca activity. No side difference in 45Ca deposition was found. The callus ash weight of the allogenous matrix-transplanted side was approximately 60% of that of the cancellous bone side. This side difference of ash weights corresponds to the estimated initial mineral content of the cancellous graft. Nontransplanted defects had very low ash weight and 45Ca activity. Thus, in the rabbit, composite grafts of bone matrix and marrow produce a bone yield comparable to that of cancellous bone.     

Tissue-engineered bone formation in vivo using a novel sintered polymeric microsphere matrix

We have evaluated in vivo a novel, polymer-based, matrix for tissue engineering of bone. A segmental defect of 15 mm was created in the ulna of New Zealand white rabbits to determine the regenerative properties of a porous polylactide-co-glycolide matrix alone and in combination with autogenous marrow and/or the osteoinductive protein, BMP-7. In this study four implant groups were used: 1) matrix alone; 2) matrix with autogenous marrow; 3) matrix with 20 microg of BMP-7; and 4) matrix with 20 microg of BMP-7 and autogenous marrow. The results showed that the degree of bone formation was dependent on the properties of the graft material. The osteoconductive sintered matrix structure showed significant formation of bone at the implant-bone interface. The addition of autogenous marrow increased the penetration of new bone further into the central area of the matrix and also increased the degree of revascularisation. The osteoinductive growth factor BMP-7 induced penetration of new bone throughout the entire structure of the implant. The most effective treatment was with the combination of marrow cells and osteoinductive BMP-7.     

Bone matrix and marrow versus cancellous bone in rabbit radial defects

Summary Implants of demineralized bone matrix induce new bone formation. In order to estimate the possible clinical usefulness of this phenomenon, autologous cancellous bone grafts were compared with composite grafts of bone matrix and marrow. Cancellous bone from the tuber ischii of the rabbit was transplanted to a preformed radial defect in the same animal. On the opposite side, a similar defect was filled with a mixture of either allogenous or autogenous bone-matrix particles and autogenous bone marrow. After 25 days, calcium 45 was injected intravenously. Three days later the animals were killed. Standardized segments of the rabbit's forearms, containing the middle of the defect, were cut out, ashed, and analyzed for ⁴⁵Ca activity. No side difference in ⁴⁵Ca deposition was found. The callus ash weight of the allogenous matrix-transplanted side was approximately 60% of that of the cancellous bone side. This side difference of ash weights corresponds to the estimated initial mineral content of the cancellous graft. Nontransplanted defects had very low ash weight and ⁴⁵Ca activity. Thus, in the rabbit, composite grafts of bone matrix and marrow produce a bone yield comparable to that of cancellous bone.     

Tendon reattachment to a metallic implant using an allogenic bone plate augmented with rhOP-1 vs. autogenous cancellous bone and marrow in a canine model.

Functionality of endoprosthetic reconstruction may be improved through secure and lasting soft tissue reattachment directly to the metallic implant surface. Tendon reattachment to the metallic surface of a titanium implant (enhanced tendon anchor, ETA) using autogenous bone plate as an interpositional structure between the tendon and metal, augmented with autogenous bone chips and marrow, provided successful mechanical and functional outcome. However, preparation of the autogenous bone plate is not practical in a clinical setting, but application of an allogenic bone plate could be an alternative. The autogenous cancellous bone and marrow may also be substituted by bone growth factors so that no autogenous bone graft is required. We hypothesized that the reconstitution of the direct tendon-bone insertion morphology in tendon reattachment to metallic implant could be achieved using allogenic cancellous bone plate augmented with autogenous cancellous bone and marrow, and that the autogenous bone grafts could be replaced by recombinant human osteogenic protein-1 (rhOP-1). In two canine groups the supraspinatus tendon was reattached unilaterally to a modified ETA implant with a highly porous metallic surface known as Tritanium Dimensionalized Metal. Allogenic bone plates saturated with rhOP-1-collagen putty were used in the OP-1 (OP) group, while plates saturated with autogenous cancellous bone and marrow were used in the bone marrow (BM) group. Functional, radiographical, mechanical and histomorphological analysis results were compared between both groups. At 15 weeks, gait analysis showed 78% and 81% recovery of preoperative weight-bearing in OP and BM groups, respectively. The calcified area around the tendon in OP group was 5.2 times larger than that in BM group (p<0.001). The ultimate tensile strength of the reattachment was 24% and 38% of the intact contralateral side in OP and BM groups, respectively, without significant difference between them. There was evidence of tendon-bone insertion transitional zones, tissue ingrowth and adhesion to the metallic surface in both groups. In conclusion, the use of the allograft combined with rhOP-1 had a similar effect as combined with autogenous cancellous bone and marrow in the tendon reattachment to the metallic surface.     

The effect of osteogenic protein-1 in instrumented and noninstrumented posterolateral fusion in rabbits.

BACKGROUND CONTEXT: The use of rigid instrumentation combined with bone graft makes intuitive sense given the requirements for vascular ingrowth, bone formation and a stable environment for the cellular events of healing to develop. However, with the advances of potent osteoinductive growth factors, the role of internal fixation may come into question. Whether bone morphogenic proteins (BMPs) would benefit from a more "stable" spinal segment for bone production and modeling remains unknown. In addition, it is unknown whether BMP and rigid fixation may have an additive effect on fusion healing. PURPOSE: This study is proposed to test the hypothesis that rigid fixation in the lumbar spine would be advantageous to achieve fusion for autogenous bone grafting, but fusion would occur regardless of fixation with the use of osteogenic protein (OP)-1. STUDY DESIGN/SETTING: A histologic and radiographic analysis of BMP in a rabbit lumbar fusion model. METHODS: Thirty-two rabbits were randomized into four groups: 1) control animals: in situ posterolateral L5-L6 arthrodesis using autogenous iliac crest bone graft; 2) fixation group: posterolateral arthrodesis L5-L6 with autogenous bone graft and interspinous fixation; 3) OP-1 group: in situ posterolateral L5-L6 arthrodesis using OP-1 and 4) combined OP-1 and fixation group. Radiographic fusion analysis was performed with computed tomography scans at 3 and 12 weeks after surgery. Decalcified histology was performed to assess tissue morphology and cellularity. RESULTS: Minimal evidence of fusion was noted at 3 weeks with autograft or OP-1. By 12 weeks, all OP-1-treated animals had solid fusion, whereas no fusion was noted in autograft animals. The addition of fixation slightly increased radiographic fusion at 3 weeks in autograft and OP-1 groups but did not affect OP-1 animals at 12 weeks where all were fused. Decalcified histologic results confirmed the proliferative bone formation noted with OP-1 and the variable cellular response with autograft. CONCLUSIONS: The results of the present study suggest that the osteoinductive effect of OP-1 may be only minimally enhanced early in the bone healing process but does not appear to be affected in the long term by spinal fixation in the rabbit intertransverse fusion model. Fixation appeared to enhance early fusion in the autograft group.     

Bone formation following OP-1 implantation is improved by addition of autogenous bone marrow cells in a canine femur defect model.

Osteogenic Protein-1 (OP-1, BMP-7) acts locally on connective tissue progenitors (CTPs) to induce bone formation. The response to OP-1 and similar agents is potentially limited by the number of local CTPs. This study tested the hypothesis that supplementing local CTPs using autogenous bone marrow will enhance bone formation at an OP-1 implant. Four 1.0-cm diameter unicortical cylindrical defects in the left proximal femur were grafted in each of seven dogs. Radial ingrowth of new bone formation was assessed at 4 weeks using micro CT. The OP-1 (3.5 mg rhOP-1 in 1 g bovine collagen I matrix) was implanted in each site combined with either clotted blood or aspirated bone marrow (BM). Bone formation was increased in the group augmented with transplanted marrow. These data suggest that increasing the local population of cells and CTPs using aspirated bone marrow can enhance the performance of OP-1, but may not eliminate the effects of site variation on the response to OP-1 and similar agents. The canine multiple femoral defect model defined in this study is well suited to quantitatively evaluate strategies for augmenting bone repair using local cell targeting and cell transplantation strategies.     

Rapid quantitative bioassay of osteoinduction.

We developed a reproducible, relatively rapid bioassay that quantitatively correlates with the osteoinductive capacity of demineralized bone matrix obtained from human long bones. We have found that Saos human osteosarcoma cells proliferate in response to incubation with demineralized bone matrix and that an index of this proliferative activity correlates with demineralized bone matrix-induced osteogenesis in vivo. The bioassay (Saos cell proliferation) had an interassay coefficient of variation of 23 +/- 2% and an intra-assay coefficient of 11 +/- 1%. Cell proliferation was normalized to a standard sample of demineralized bone matrix with a clinically high osteoinductive capacity, which was assigned a value of one. The Saos cell proliferation for each sample was related to the standard and assigned a value placing it into the low (0.00-0.39), intermediate (0.40-0.69), or high (0.70-1.49) osteoinductive index group. Osteoinduction of human demineralized bone matrix was quantitated by expressing new bone formation as a function of the total bone volume (new bone plus the demineralized bone powder). The demineralized bone matrix was placed in pouches formed in the rectus abdominis muscles of athymic rats, and endochondral bone formation was assessed at 35 days following implantation, when marrow spaces in the ossicles were formed by new bone bridging the spaces between demineralized bone matrix particles. The proliferative index correlated with the area of new bone formation in histological sections of the newly formed ossicles. When the proliferative index (the osteoinductive index) was divided into low, intermediate, and high groups, the correlation between it and new bone formation (osteoinduction) was 0.850 (p < 0.0005) in 25 samples of demineralized bone matrix. There was no overlap in the osteoinduction stimulated between the samples with low and high osteoinductive indices. We conclude that the proliferation assay is useful for the routine screening of bone allograft donors for osteoinductive potential. Furthermore, the two-dimensional area of new bone formation, as it relates to total new bone area, is a quantitative measure of osteoinduction.     

In vitro and in vivo optimization of impaction allografting by demineralization and addition of rh-OP-1.

Impaction allografting is a bone tissue engineering technique currently used in lower limb reconstruction orthopedic surgery. Our hypothesis was that biological optimization can be achieved by demineralization and addition of osteogenic protein-1 (OP-1) to the allograft. The objective of our in vitro study was to evaluate human mesenchymal stem cell (MSC) proliferation (Alamar Blue assay, titrated thymidine assay, total DNA Hoechst 33258, and scanning electron microscopy) and osteogenic differentiation (alkaline phosphatase assay) in two types of impacted carrier, namely, demineralized bone matrix (DBM) and insoluble collagenous bone matrix (ICBM), with or without OP-1. The objective in vivo was to compare the osteogenic potential of impacted DBM with or without OP-1, with that of impacted fresh frozen allograft (FFA), again with or without OP-1. DBM + OP-1 optimized osteoinduction and significantly improved (p < 0.05) proliferation and differentiation in comparison to the majority of all other graft preparation in vitro. In addition, DBM + OP-1 was significantly superior, with regard to osteogenesis, compared to the impacted FFA alone (p < 0.001), FFA + OP-1 (p = 0.01) and DBM alone (p = 0.02) in vivo. We propose that partial demineralization and addition of OP-1 provides a good method for improving the osteoinductive properties of fresh allograft currently used in the impaction grafting technique.     

Cranioplasty using allogeneic perforated demineralized bone matrix with autogenous bone paste

The efficacy of allogeneic perforated demineralized bone matrix with autogenous bone paste in the treatment of full-thickness cranial defects was evaluated in 10 consecutive patients between June 1998 and December 1998. The skull defects resulted from trauma in 9 patients and removal of a cranial tumor in 1 patient. The size of the skull defects ranged from 8 x 6 cm to 11 x 12.5 cm. Follow-up averaged 33 months for all patients. Postimplantation evaluations included serial photographs, repeated physical examination, and three-dimensional computed tomography for all patients. Visual inspection of the implanted biomaterial 6 months later was possible in 1 patient. The contour of the reconstructed skull was acceptable aesthetically without any secondary depression noted during the follow-up period. Three-dimensional computed tomographic scans taken 2 years after implantation indicated that the allogeneic perforated demineralized bone matrix provided a matrix for new bone formation with remarkable osteoinductive potential for new bone formation. The autogenous bone paste was able to caulk the demineralized bone matrix and fill the contour irregularities and gaps of the reconstructed cranium. The results from this clinical study indicated that allogeneic perforated demineralized bone matrix with autogenous bone paste is a promising alternative to an autogenous bone graft and or alloplastic material for cranioplasty.     

Decalcified and undecalcified cancellous bone block implants do not heal diaphyseal defects in dogs

Summary In a previous study it has been shown that granulae of decalcified bone matrix do not induce bony healing of 8-week-old mid-diaphyseal defects in dogs. The aim of this study was to test whether osteoinduction combined with the osteoconductive mechanisms provided by the natural structure of cancellous bone blocks would yield better results. A 30-mm-long diaphyseal defect of the left ulna was created in eight adult mongrel dogs and the bone was stabilized with a plate. A Silastic spacer was inserted in the defect for 8 weeks, followed by implantation of frozen undecalcified or decalcified allogeneic cancellous bone blocks for 16 weeks. Healing was analyzed using morphologic methods. At 16 weeks after implantation all grafts had been resorbed. In the decalcified group one defect healed, while none in the other group did so. The implant material was bioassayed in nude rats for osteoinductivity, which was found to be low in decalcified matrix and not detectable in undecalcified bone. Conclusion: Allogeneic cancellous bone blocks, demineralized or not, have no osteoinductive capacity and no osteoconductive function that promotes healing of mid-diaphyseal bone defects in dogs.     

Evaluation of bovine-derived bone protein with a natural coral carrier as a bone-graft substitute in a canine segmental defect model

The efficacy of a bone-graft substitute (bovine-derived bone protein in a carrier of natural coral) in the healing of a segmental defect of a weight-bearing long bone was evaluated. Twenty dogs, divided into two groups, underwent bilateral radial osteotomies with creation of a 2.5 cm defect. On one side of each dog, the defect was filled with autogenous cancellous bone graft. Contralateral defects received, in a blinded randomized fashion, cylindrical implants consisting of natural coral (calcium carbonate) or calcium carbonate enhanced with a standard dose of bovine-derived bone protein (3.0 mg/implant; 0.68 mg bone protein/cm³). The limbs were stabilized with external fixators, and all animals underwent monthly radiographs. They were killed at 12 (group 1) or 24 (group 2) weeks, and regenerated bone was Studied by biomechanical testing and histology. Radiographic union developed in all 20 radii with autogenous cancellous bone grafts and in all 10 of the radii with the composite implants. None of the radii with implants of calcium carbonate alone showed radiographic evidence of union. This represented a statistically significant difference between implant types. In addition, calcium carbonate implants both with and without bone protein demonstrated radiographic evidence of near total resorption of the radiodense carrier by 12 weeks. This resorption facilitated radiographic evaluation of healing. Mean values for. biomechanical parameters of radii with the composite implants exceeded those for the contralateral controls at 12 and 24 weeks; the difference was statistically significant at 12 weeks. Histology revealed scant residual calcium carbonate carrier at either time in the defects with calcium carbonate implants; however, a moderate amount was present in defects with the composite implants. In these specimens, the residual carrier was completely surrounded by newly formed bone that may have insulated the calcium carbonate from further degradation. The present study used a carrier of granular calcium carbonate reconstituted with bovine type-I collagen to deliver an osteoinductive protein to the defect site. This carrier is of nonhuman origin (eliminating the risk of disease transmission or antigenicity) and resorbs rapidly. In this model, bovine-derived bone protein in a natural coral carrier performed consistently better than the gold standard autogenous cancellous bone graft in terms of the amount of bone formation and strength of the healed defect. This may have implications for removal of hardware or resumption of weight-bearing in certain clinical situations. These data also indicate that coralline calcium carbonate alone. represents a poor option as a bone-graft substitute in this critical-sized segmental defect model.     

A study of 23 unicameral bone cysts of the calcaneus: open chip allogeneic bone graft versus percutaneous injection of bone powder with autogenous bone marrow

BACKGROUND: The treatment of unicameral bone cyst varies from percutaneous needle biopsy, aspiration and local injection of steroid, autologous bone marrow, or demineralized bone matrix to curettage and open bone-grafting. The purpose of this study was to compare the results of open chip allogeneic bone graft versus percutaneous injection of demineralized bone powder with autogenous bone marrow in management of calcaneal cysts. MATERIALS AND METHODS: Twenty-three calcaneal unicameral cysts in 20 patients were treated. Lyophilized irradiated chip allogeneic bone (CAB) and autogenous bone marrow were used for treatment of 13 cysts in 11 patients, and 10 cysts in 9 patients were treated with percutaneous injection of irradiated allogeneic demineralized bone powder (DBP) and autogenous bone marrow. There were 11 males and 9 female patients with mean age of 17 years. RESULTS: The patients were followed for an average of 49.4 months. Complete healing was achieved in 9 cysts treated with chip allogeneic bone and in 5 cysts treated with powdered bone. Four cysts treated with CAB and 3 cysts treated with DBP healed with a defect. Two cysts treated with powdered bone and autogenous bone marrow were classified as persistent. No infections or pathological fractures were observed during the followup period. CONCLUSION: Percutaneous injection of a mixture of allogeneic bone powder with autogenous bone marrow is a minimal invasive method and could be an effective alternative in the treatment of unicameral calcaneal bone cysts. The postoperative morbidity was low, the hospital stay was brief, and patient's comfort for unrestricted activity was enhanced.     

Effects of lathyritic drugs and lathyritic demineralized bone matrix on induced and sustained osteogenesis

Demineralized bone matrix was implanted in normal and lathyritic rats. At 2 weeks, the bone that formed in the lathyritic animals had an elevated alkaline phosphatase activity and a reduced calcium content compared with the controls. Four weeks after implantation, these biochemical parameters were reversed, with a decrease in alkaline phosphatase activity and an increase in calcium content to control levels. the histology of the recovered implants revealed new bone formation. Lathyritic demineralized bone matrix was prepared from bones of rats fed β-aminopropionitrile for 2 weeks (2-week BAPN-DBM) or 4 weeks (4-week BAPN-DBN), and was implanted in normal rats. Two weeks after implantation, both preparations of lathyritic demineralized bone matrix demonstrated early bone formation, although alkaline phosphatase activity and calcium content were reduced. By 4 weeks after implantation, no biochemical or histological evidence of bone formation remained at the site of the 4-week BAPN-DBM implants; continued but reduced bone formation was observed at the site of the 2-week BAPN-DBM implants. Reconstitution of inactivated normal demineralized bone matrix with the guanidine-soluble extracts restored the osteoinductive capacity. However, reconsistution of inactivated lathyritic demineralized bone matrix (4-week BAPN-DBM) failed to restore the osteoinductive capacity. These results indicate that the degree of crosslinking of the collagen matrix that acts as a carrier for osteoinductive proteins plays a key role in inducing and sustaining osteogenesis.     

Incorporation of impacted morselized bone allografts in rabbits

Morselized bone allografts have been used for the treatment of bone stock loss in orthopedic revision surgery with encouraging results. However, several parameters can influence the graft incorporation including the processing treatments. This experimental work used a cavitary bone defect in 90 rabbits to evaluate the sequence of incorporation of three different kinds of morselized bone allografts: uncryopreserved cancellous bone, freeze-dried cancellous bone, and totally demineralized cortical bone each of which were prepared in accordance with our rigid protocol. Revascularization and remodeling of the transplanted bone grafts were evident upon histological evaluation. Bone apposition and bone resorption resulted in a mixture of graft and new bone. Mineralized cancellous grafts showed great osteoconductive capacity, whereas demineralized cortical grafts showed an intense osteoinductive capacity and a weak osteoconductive capacity. In a general evaluation, cryopreserved cancellous bone grafts showed superior biological efficacy for reconstruction of experimental bone defects, closely followed by freeze-dried cancellous bone grafts, and, finally, by demineralized cortical bone grafts. These results validate our protocol for the processing and preservation of these three kinds of bone grafts.     

Platelet-derived growth factor inhibits demineralized bone matrix-induced intramuscular cartilage and bone formation. A study of immunocompromised mice

BACKGROUND: Platelet-derived growth factor (PDGF) has been proposed as a therapeutic agent to promote bone-healing. The purpose of this study was to examine the effect of PDGF on the ability of human demineralized bone matrix to induce bone formation in a nude-mouse muscle-implantation model. We also examined whether platelet-rich plasma, which contains PDGF, also modulates osteoinduction in this model. METHODS: Human demineralized bone matrix, previously shown to be osteoinductive in the calf muscles of nude mice, was mixed with PDGF-BB (0, 0.1, 1, and 10 microg/10 mg of demineralized bone matrix) and was implanted bilaterally in the calf muscles of immunocompromised (nu/nu) mice (six mice in each group). Heat-inactivated demineralized bone matrix was used as a control. Tissue was harvested at fourteen, twenty-eight, and fifty-six days after implantation. Platelet-rich plasma was prepared from the blood of a healthy donor with use of the Harvest PRP preparation device, activated with thrombin, and mixed with active and inactive demineralized bone matrix. Fifty-six days post-implantation, tissues were harvested. Osteoinduction was assessed with use of a qualitative scoring system and with quantitative histomorphometry. RESULTS: Cartilage was present at fourteen days in all tissues that had received an implant, but the amount decreased as the PDGF concentration increased. PDGF reduced bone formation at twenty-eight days in a dose-dependent manner. This inhibitory effect was resolved by fifty-six days, except in tissues in which demineralized bone matrix and 10 microg of PDGF had been implanted. In sites treated with 10 microg of PDGF, the area of new bone was decreased and the area of bone marrow was reduced at twenty-eight and fifty-six days. PDGF also appeared to retard resorption of demineralized bone matrix in a dose-dependent manner. Platelet-rich plasma reduced osteoinduction by human demineralized bone matrix that had high osteoinductive activity and had no effect on osteoinduction by demineralized bone matrix with low activity. CONCLUSIONS: PDGF inhibits, in a dose-dependent manner, intramuscular osteoinduction and chondrogenesis by demineralized bone matrix in immunocompromised mice. Platelet-rich plasma also reduces the osteoinductivity of active demineralized bone matrix.     

The evaluation of a biphasic calcium phosphate ceramic for use in grafting long-bone diaphyseal defects

The effectiveness of a sintered hydroxyapatite-tricalcium phosphate (HA-TCP) ceramic in bridging large diaphyseal defects in the canine ulna was studied. One-hundred percent morselized HA-TCP, a 50:50 mixture of morselized HA-TCP, and autogenous cancellous bone, and 100% autogenous cancellous bone were used to bridge 2.5-cm defects in the left ulnae of three groups of six dogs each. At 24 weeks the ulnae were explanted and studied by radiography, microradiography, mechanical testing, and histology. Pure HA/TCP was not osteoinductive, and four of six ulnae in this group progressed to a fibrous nonunion. The HA/TCP-cancellous bone mixture and pure cancellous bone were approximately equal in effect, leading to good callus formation at 4 weeks and strong bony union by 24 weeks, with no evidence of bioincompatibility. Morselized HA/TCP promises to be useful as a graft extender when mixed with autogenous cancellous bone.     

自体骨髓促进引导性骨再生

目的　研究自体骨髓增强引导性骨再生 (GBR)修复骨缺损的能力。方法　 18只兔分为 5组 ,每组 3只 (第 5组 6只 ) ,造成双桡骨干 10 mm骨缺损 ,以硅胶管桥接骨断端 ,实验组于 0、2和 4周分别在硅胶管内注射自体骨髓 0 .3ml;对照组于相同时间点注射等量外周静脉血。在不同时间内作 X线片、大体、组织学观察及生化检测。结果　实验组成骨活跃 ,10周骨缺损完全修复 ,对照组各时间点均较实验组差 ,10周时仍无 1只兔骨性愈合。术后 2、4周实验组钙及碱性磷酸酶含量明显高于对照组。结论　自体骨髓可明显增强 GBR修复骨缺损的能力     

The use of demineralized bone matrix in the repair of segmental defects. Augmentation with extracted matrix proteins and a comparison with autologous grafts

A soluble protein component of bone, bone morphogenetic protein, and decalcified bone matrix have been shown to induce the formation of bone in extraosseous tissue. Clinical and animal studies investigating the use of these materials as bone grafts have shown radiographic and histological evidence of formation of bone, but the clinical usefulness of these grafts remains unknown. This study compared the healing processes when plasma-coated demineralized bone matrix and autologous cancellous bone were used to graft segmental defects of bone. A standard procedure was used to make a two-centimeter defect bilaterally in the ulna of forty-eight skeletally mature New Zealand White rabbits. In each rabbit, one ulnar defect was grafted with autologous citrated plasma-coated demineralized bone matrix while the other defect served as a control and was grafted with either autologous cancellous bone from the iliac crest, demineralized bone matrix, or demineralized bone matrix augmented with bone proteins that had been extracted with guanidinium hydrochloride. The ulnar defect was stabilized by the intact radius, and no supplemental device was necessary for fixation. To examine spontaneous healing in this model, one group of rabbits had a control defect that was not grafted. The grafts were periodically evaluated by radiographs, and twelve weeks after surgery the grafts were harvested and tested to failure in a standard torsion-test machine. The mechanical parameters were calculated, and histological examination of major fragments of the grafts was performed. The results of the radiographic and histological evaluation showed that all of the grafted ulnae healed, with fusion of the graft to the cut ends of the defect and reformation of approximately normal anatomy. No ungrafted ulnar defects healed. The results from the mechanical tests were evaluated by comparing the defect that was grafted with plasma-coated demineralized bone matrix with the control graft in each animal. These data showed that: twelve weeks after grafting, the normal ulnae were significantly stronger than the ulnae that had been grafted with plasma-coated demineralized bone matrix; the ulnae that had been grafted with plasma-coated demineralized bone matrix and those that had been grafted with autologous bone were equivalent in strength; and twelve weeks after grafting, grafts of demineralized bone matrix that were augmented with extracted bone proteins were significantly stronger than those that had not been so augmented.