Demineralized Bone Matrix Group Research Articles

In vitro and in vivo investigations on bone regeneration potential of laminated hydroxyapatite/gelatin nanocomposite scaffold along with DBM

Bone regeneration ability of a scaffold strongly depends on its structure and the size of its components. In this study, a nanostructured scaffold was designed for bone repair using nano hydroxyapatite (nHA) (8–16 nm × 50–80 nm) and gelatin (GEL) as main components. In vitro investigations of calcium matrix deposition and gene expression of the seeded cells for this scaffold, demineralized bone matrix (DBM), scaffold plus DBM, and the control group were carried out. Bone regeneration in rat calvarium with critical defect size after 1, 4, and 8 weeks post implantation was investigated. The calcium matrix depositions by the osteoblast and RUNX2, ALP, osteonectin, and osteocalcin gene expression in scaffold were more significant than in other groups. Histomorphometry analysis confirmed in vitro results. In vitro and in vivo bone regeneration were least in scaffold plus DBM group. Enhanced effects in scaffold could be attributed to the shape and size of nHA particles and good architecture of the scaffold. Reduction of bone regeneration might be due to tight bonding of BMPs and nHA particles in the third group. Results obtained from this study confirmed that nano-scale size of the main components and the scaffold architecture (pore diameter, interconnectivity pores, etc.) have significant effects on bone regeneration ability of the scaffold and are important parameters in designing a temporary bone substitute.

Effects of Demineralized Bone Matrix on Tendon-Bone Healing in an Intra-articular Rodent Model

Background: Techniques to improve and accelerate tendon-bone healing could be advantageous in anterior cruciate ligament (ACL) reconstruction. Effects of demineralized bone matrix (DBM) on intra-articular tendon-bone healing have not been examined. Hypothesis: Demineralized bone matrix has the potential to convey osteoinductive growth proteins to the site of healing at the tendon-bone interface. We hypothesized that the presence of DBM will result in more bone formation and hasten tendon-bone healing. Study Design: Controlled laboratory study. Methods: Fifty-six female athymic rnu/rnu (nude) rats were used. Rats were randomly allocated into 2 groups (control or treatment). The control group underwent an ACL reconstruction, while the treatment group had human DBM implanted in the tendon graft and bone tunnel before reconstruction. Rats were sacrificed at 2 (n = 8), 4 (n = 24), and 6 (n = 24) weeks for histological, and immunohistochemical (t = 2, 4, and 6 weeks), and biomechanical testing and micro–computed tomography (t = 4 and 6 weeks) end points. Results: Our findings suggest that in the presence of DBM, tendon-bone healing is augmented by increased woven bone formation and enhanced bone remodeling as indicated by histology and micro–computed tomography. This ultimately resulted in a statistically significant increase in peak load to failure of the tendon-bone interface at 4 weeks (DBM group: 5.96 ± 1.36 N; control group: 2.86 ± 0.7 N) and 6 weeks (DBM group: 9.13 ± 0.97 N; control group: 5.81 ± 1.1 N). Conclusion: Demineralized bone matrix at the tendon-bone interface promotes healing between the tendon and bone in a rodent ACL model. Clinical Relevance: Introduction of osteoinductive DBM at the tendon-bone interface during ACL reconstructive surgery may improve short-term outcomes.

Adjuncts in posterior lumbar spine fusion: comparison of complications and efficacy

The purpose of this study was to define the efficacy of recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) and Demineralized Bone Matrix (DBM) compared to autograft in posterior lumbar spine fusion by comparing complication rates. During a 7-year period (2003-2009), all patients undergoing posterior lumbar fusion were retrospectively evaluated within a large orthopedic surgery private practice. Patient demographics, comorbidities, number of levels, type of surgery, and types of bone void filler and osteobiologics were analyzed. Complications were defined as reoperation secondary to failed symptomatic fusion, hyper-reaction with fluid collections, bone overgrowth, and infections. 1,398 patients were evaluated with 41.1% males and 58.9% females. Mean age was 60years and BMI 30.6kg/m². Patients were subdivided in treatment groups: rhBMP-2, 947 (67.7%), DBM 306 (21.9%), and autograft 145 (10.4%). The overall infection rate was 2.1%. No significant differences were found between the three groups. The incidence of seroma formation was higher in the BMP group (3.2%) than in the DBM or autograft group (2.0 and 1.4%, respectively) but this was not significant (p=0.286 and p=0.245, respectively). 103 patients (7.4%) underwent redo surgery for clinically significant nonunion. We found significantly fewer nonunions (4.3%) in the rhBMP-2 group (p<0.001) compared to the DBM or autograft group (13.1 and 15.2%, respectively). ICBG is the gold standard. DBM leads to comparable fusion rates and does not increase infection or seroma formation. rhBMP-2 supplementation instead of ICBG or bone marrow aspirate results in higher fusion rates compared to autograft alone or autograft plus DBM.

Grafton and Local Bone Have Comparable Outcomes to Iliac Crest Bone in Instrumented Single-Level Lumbar Fusions

Prospective multicenter randomized clinical trail. The goal of our 2-year prospective study was to perform a randomized clinical trial comparing the outcomes of Grafton demineralized bone matrix (DBM) Matrix with local bone with that of iliac crest bone graft (ICBG) in a single-level instrumented posterior lumbar fusion. There has been extensive research and development in identifying a suitable substitute to replace autologous ICBG that is associated with known morbidities. DBMs are a class of commercially available grafting agents that are prepared from allograft bone. Many such products have been commercially available for clinical use; however, their efficacy for spine fusion has been mostly based on anecdotal evidence rather than randomized controlled clinical trials. Forty-six patients were randomly assigned (2:1) to receive Grafton DBM Matrix with local bone (30 patients) or autologous ICBG (16 patients). The mean age was 64 (females [F] = 21, males [M] = 9) in the DBM group and 65 (F = 9, M = 5) in the ICBG group. An independent radiologist evaluated plain radiographs and computed tomographic scans at 6-month, 1-year, and 2-year time points. Clinical outcomes were measured using Oswestry Disability Index (ODI) and Medical Outcomes Study 36-Item Short Form Health Survey. Forty-one patients (DBM = 28 and ICBG = 13) completed the 2-year follow-up. Final fusion rates were 86% (Grafton Matrix) versus 92% (ICBG) (P = 1.0 not significant). The Grafton group showed slightly better improvement in ODI score than the ICBG group at the final 2-year follow-up (Grafton [16.2] and ICBG [22.7]); however, the difference was not statistically significant (P = 0.2346 at 24 mo). Grafton showed consistently higher physical function scores at 24 months; however, differences were not statistically significant (P = 0.0823). Similar improvements in the physical component summary scores were seen in both the Grafton and ICBG groups. There was a statistically significant greater mean intraoperative blood loss in the ICBG group than in the Grafton group (P < 0.0031). At 2-year follow-up, subjects who were randomized to Grafton Matrix and local bone achieved an 86% overall fusion rate and improvements in clinical outcomes that were comparable with those in the ICBG group.

Effects of demineralized bone matrix on tendon-bone healing: an in vivo, experimental study on rabbits

The aim of this study was to investigate the effects of demineralized bone matrix (DBM) on tendon-bone healing. The extensor digitorum longus tendon was fixed with pegged suture technique in a tunnel at the proximal tibia in both legs of 12 New Zealand rabbits. Rabbit DBM was applied in the tunnel on the right limbs before fixation (study group), while the fixation was performed without DBM in the left legs (control group). Randomly, four rabbits were sacrificed at the 3rd, four rabbits at the 6th and the remaining four rabbits at the 9th week with an intravenous high dose (200 mg/kg) pentothal and both legs were collected for histological analysis. Each specimen was blindly and independently examined to assess fibrocartilage formation, new bone formation, tendon graft bonding to adjacent tissue and Sharpey's fiber formation. A scoring system was used for quantification of histopathological analysis. The DBM group showed higher number of Sharpey's fibers, slightly increased fibrocartilage formation and new bone formation scores than the control group in the 3rd week. All histological scores were similar in both groups in the 6th and 9th weeks (p>0.05). DBM increased new bone formation and the number of Sharpey's fibers in a bone tunnel animal model within the first three weeks of tendon-bone healing process.

Bone Tissue Engineering in Oral Surgery: A New Method of Bone Development in Periodontal Surgery

This article describes the development of a new surgical approach to periodontal treatment. Twenty patients who suffered from bone defects without existing bony walls due to adult periodontitis were treated in three different groups using methods of bone tissue engineering. At that time no surgical technique existed that could be applied to those patients to generate new bone. The periodontal surgeries were performed between 2004 and 2008. All patients received follow-up examinations at 6, 12, and 24 months after surgical procedure. Measured parameters were compared to baseline. The surgical approach and the augmentation material have been improved based on the results of the previous group. This strategy was applied because of the ethical fact that a medical treatment of patients has to be carried out with the knowledge and experience of previous settings. All groups received recombinant human bone morphogenetic protein 2 and platelet-rich plasma. The above-mentioned procedure had been approved in other indications in the field of oral and maxillofacial surgery. The first group underwent conventional muco-periosteal flap technique and obtained an augmentation with absorbable collagen sponge (ACS). The second and third groups were treated using endoscopically assisted microsurgery due to wound healing disturbances that appeared in the first group. The augmentation was carried out with demineralized bone matrix (DBM) instead of ACS (group 2) or tricalciumphosphate as a further development instead of DBM (group 3). The radiological control 12 months (group 1), 18 months (group 2), and 2 years (group 3) after surgery proved the following results-first group: 1.7 mm (average) vertical bone development (VBD); second group: 2.5 mm (average) VBD; third group: 3.2 mm (average) VBD. These results of single patient treatment open new ways into periodontal surgery. They have to be confirmed by prospective case series and multicenter studies.

Grafting Using Injectable Calcium Sulfate in Bone Tumor Surgery: Comparison with Demineralized Bone Matrix-based Grafting

BackgroundInjectable calcium sulfate is a clinically proven osteoconductive biomaterial, and it is an injectable, resorbable and semi-structural bone graft material. The purpose of this study was to validate the clinical outcomes of injectable calcium sulfate (ICS) grafts as compared with those of a demineralized bone matrix (DBM)-based graft for filling in contained bony defects created by tumor surgery.MethodsFifty-six patients (41 males and 15 females) with various bone tumors and who were surgically treated between September 2003 and October 2007 were included for this study. The patients were randomly allocated into two groups, and either an ICS graft (28 patients) or a DBM-based graft (28 patients) was implanted into each contained defect that was developed by the surgery. The radiographic outcomes were compared between the two groups and various clinical factors were included for the statistical analysis.ResultsWhen one case with early postoperative pathologic fracture in the DBM group was excluded, the overall success rates of the ICS and DBM grafting were 85.7% (24/28) and 88.9% (24/27) (p > 0.05), respectively. The average time to complete healing was 17.3 weeks in the ICS group and 14.9 weeks in the DBM group (p > 0.05). Additionally, the ICS was completely resorbed within 3 months, except for one case.ConclusionsAlthough the rate of resorption of ICS is a concern, the injectable calcium sulfate appears to be a comparable bone graft substitute for a DBM-based graft, with a lower cost, for the treatment of the bone defects created during surgery for various bone tumors.

Osteoinductive activity of demineralized bone matrix and deprotenized bone derived from human avascular necrotic femoral head

To observe the osteoinductive activity of demineralized bone matrix (DBM) and deproteinized bone (DPB) made from human avascular necrotic femoral head. The femoral head was cut into pieces with the size of 3 mm x 3 mm x 5 mm, which were made into DBM and DPB. These two kinds of biomaterials were cocultured with human bone mesenchymal stem cells (hBMSCs). Monolayer cells without biomaterials were cultured as control. Proliferative activity of hBMSCs was evaluated on days 1, 3, 5, 7 and 14. The concentration of alkaline phosphatase (ALP), osteocalcin (OC), and Ca(2+) were detected on days 1, 7, 14 and 21. Cells cultured in DBM showed higher proliferative activity than did in DPB and monolayer cells (F =39.773, P <0.01). DBM and DPB also had osteoinductive activity. The concentrations of ALP (F=93.162, P <0.01), OC (F =236.852, P < 0.01), Ca(2+)(F =80.711, P <0.01) of DBM group were significantly higher than that of DPB and control groups. In vitro, DBM and DPB made from avascular necrotic femoral head have osteoinductive activity when cocultured with hBMSCs, and the former is stronger than the latter.

Experimental bone defect healing with xenogenic demineralized bone matrix and bovine fetal growth plate as a new xenograft: radiological, histopathological and biomechanical evaluation

The following study was designed to evaluate xenogenic bovine demineralized bone matrix (DBM) and new xenograft (Bovine fetal growth plate) effects on bone healing process. Twenty male White New Zealand rabbits were used in this study. In group I (n = 10) the defect was filled by xenogenic DBM and in group II (n = 10) the defect was filled by a segment of bovine fetal growth plate and was fixed by cercelage wire. Radiological, histopathological, and biomechanical evaluations were performed blindly and results scored and analyzed statistically. Statistical tests did not support significant differences between two groups radiographically (P > 0.05). There was a significant difference for union at the 28th postoperative radiologically (P < 0.05). Xenograft was superior to DBM group at the 28th postoperative day for radiological union (P < 0.03). Histopathological and biomechanical evaluation revealed no significant differences between two groups. In conclusion, the results of this study indicate that satisfactory healing occurred in rabbit radius defect filled with xenogenic bovine DBM and xenogenic bovine fetal growth plate. Complications were not identified and healing was faster in two grafting groups.

Evaluation of Partially Demineralized Osteoporotic Cancellous Bone Matrix Combined with Human Bone Marrow Stromal Cells for Tissue Engineering: An In Vitro and In Vivo Study

Allogenous demineralized bone matrix (DBM) represents a potential scaffold for bone tissue engineering due to its close relation in structure and function with autologous bone, but its supply is often restricted by donor availability. Thus, an expanded source of human bone is needed. The aim of this study was to evaluate the capacity of partially DBM scaffolds derived from allogenous cancellous bone of osteoporotic femurs to support osteogenesis of human bone marrow stromal cells (BMSCs) in vitro and in vivo in order to assess their potential use in bone tissue-engineering strategies. Human BMSCs of passage 2 were seeded either on osteoporotic bone-derived DBM scaffolds or on normal bone-derived scaffolds and cultured in osteogenic medium for 14 days. To assess the in vitro proliferation potential and osteogenic differentiation of BMSCs on scaffolds, scanning electronic microscopy observation, DNA content assays, and measurements of alkaline phosphatase activity and osteocalcin content were applied; the results displayed no significant differences between the osteoporotic DBM group and the normal DBM group. After 2 weeks of subculture in vitro, the BMSC/DBM composites were subcutaneously implanted into athymic mice for 8 weeks to evaluate their in vivo bone-forming ability. Histological examination showed tissue-engineered bone formation in the DBM pores in both groups, and no significant differences were observed in either the extent or frequency of new bone formation between these two groups. Based on these results, it can be concluded that osteoporotic bone-derived DBM may serve as a promising scaffold for bone tissue engineering.

Tendon bone healing can be enhanced by demineralized bone matrix: A functional and histological study

Rotator cuff repair surgery has high failure rates, with tendon reattachment to bone remaining a challenging clinical problem. Increasing the integrity of the healing tendon-bone interface has been attempted by adopting a number of different augmentation strategies. Because of chondrogenic and osteogenic properties we hypothesise that demineralized bone matrix (DBM) augmentation of a healing tendon-bone interface will result in improved function, and a morphology that more closely resembles that of a normal enthesis, compared with nonaugmented controls in an ovine patellar tendon model. The right patellar tendon was detached from its insertion and reattached to an osteotomized bone bed using suture anchors. Two groups were analyzed, the control group (without augmentation) and the DBM group (DBM interposed between the tendon and bone). Animals were sacrificed at 12 weeks. Force plate, mechanical, and histomorphometric analyses were performed. Tendon repairs failed at a rate of 33 and 0% for the control and DBM groups, respectively. DBM augmentation resulted in significantly improved functional weight bearing and increased amounts of fibrocartilage and mineralized fibrocartilage. This study shows that DBM enhances tendon-bone healing and may reduce the high failure rates associated with rotator cuff repair clinically.

The Use of Demineralized Bone Matrix for Grafting During Le Fort I and Chin Osteotomies: Techniques and Complications

To examine the use of demineralized bone matrix (DBM) in maxillary and chin orthognathic surgery. The use of DBM in orthognathic surgery has not been reported in the literature. A retrospective review of the orthognathic surgeries performed in 1 university was conducted. Medical records were assessed to determine the materials used, complications, and details of re-operations required. There were 113 suitable patients identified. The DBM group (88 patients) consisted of 61 Le Fort I osteotomies and 46 genioplasties; the non-DBM group (25 patients) consisted of 25 Le Fort I osteotomies and 4 genioplasties. The mean follow-up period was 5.9 months for the DBM group and 6 months for the non-DBM group. There was only 1 technique of applying DBM to genioplasties, but a variety of different graft material combinations was used in the Le Fort I osteotomies. The only significant Le Fort I complication was maxillary sinusitis; its incidence was 3.3% (2 out of 61) for the DBM group, versus 8% (2 out of 25) in the non-DBM group. All the genioplasties had no complications. There were 4 cases of Le Fort I osteotomies which were re-entered (2 cases for suspected infection and 2 cases for re-osteotomies due to occlusal malalignment) and they showed good bony healing. The use of DBM does not significantly increase complications and is suitable to be used in both the maxilla and chin during orthognathic surgery.

Autograft versus allograft with or without demineralized bone matrix in posterolateral lumbar fusion in rabbits

Posterolateral spinal fusions are performed to treat different spinal disorders. Autograft continues to be the gold standard; it is, however, associated with donor site morbidity and limited sources. Allograft has been used, but has been reported to result in lower fusion rates. Demineralized bone matrix (DBM) has also been used and reportedly increases the fusion rate in a variety of critical defect models. Different forms of DBM are available, not all have been independently studied. To evaluate the effect of a xenogenic DBM added to allograft on the fusion rate of posterolateral lumbar spine arthrodesis the authors designed an experimental study comparing posterolateral fusion rate using autograft, allograft, and allograft plus a xenogenic DBM in a validated animal model. A bilateral, 1-level (L4-5) intertransverse process fusion was performed in 45 male New Zealand rabbits. Iliac crest bone graft was harvested bilaterally from each rabbit. The rabbits were randomly assigned to 3 groups: Group I, Autograft, 15 rabbits; Group II, Allograft, 15 rabbits; and Group III, Allograft plus DBM in a paste form (Dynagraft). The animals were killed 8 weeks after surgery. Fusion was assessed radiographically and by manual palpation by 2 independent observers. The results were analyzed using the Fisher exact test and chi-square test. The fusion rate was 46.6% (7 of 15 rabbits) in the autograft group, 33.3% (5 of 15 rabbits) in the allograft group, and 33.3% (5 of 15 rabbits) in the allograft plus DBM group (p > 0.05). Autograft produced a higher fusion rate than allograft in this spinal fusion rabbit model, but the difference was not statistically significant. Allograft plus xenogenic DBM showed the same fusion rate as allograft alone.

Fusion Rates After Thoracoscopic Release and Bone Graft Substitutes in Idiopathic Scoliosis

A retrospective assessment of fusion rates using either morselized allograft bone or demineralized bone matrix (DBM) following video-assisted thoracoscopic surgery (VATS) in idiopathic scoliosis. To compare fusion rates between allograft bone and demineralized bone matrix (Grafton DBM Flex) following VATS using on standard standing lateral spine radiographs. Both VATS and bone graft substitutes are accepted surgical techniques. However, their concomitant use in spinal deformity surgery has not been previously reported. Bone graft substitute has the advantage of decreasing operative time, blood loss, and donor site morbidity associated with autografts. Anterior thoracic discectomies were performed using VATS. Forty patients with 1 year or more follow-up were evaluated-12 with morselized allograft bone (Allograft group) and 28 with folded Grafton DBM Flex (DBM group). Factors analyzed included age, number of anterior levels fused, operative time, anterior perioperative blood loss, curve correction, and fusion rates. Clinical and radiographic evaluations were performed before surgery and at month, 1 year, and at most recent follow-up. Interbody fusion was assessed on standing lateral radiographs using the Newton et al 4-level grading scale. There were no significant differences in age at surgery, number of anterior vertebral levels fused, anterior operative time per level, anterior intraoperative blood loss, chest tube drainage and duration, or total perioperative anterior blood loss between the 2 groups. Percent curve correction from before surgery to the most recent follow-up were very similar in both Allograft (68%) and DBM groups (67%). At most recent assessment, 60 of 73 disc spaces (82%) in the Allograft group and 100 of 109 disc spaces (92%) in the DBM group were rated as radiographically fused (Newton et al Grade I and II). There was no significant difference between the 2 groups (P = 0.088). No patients were observed to have crankshaft, pseudoarthrosis or hardware failure. There were no complications related to the bone graft material used. Demineralized bone matrix (Grafton DBM Flex) seem to be an effective bone graft substitute in thoracoscopic surgery for idiopathic scoliosis.

Molded Vascularized Neo-ossicle Formation in Silicone Chambers

Vascularized bone grafts generally achieve their aims but are not used frequently owing to donor site morbidity and limited supply. To bioengineer an alternate vascularized bone graft, we developed a novel silicone bone reactor capable of producing vascularized neo-ossicles when appropriate osteoprecursor elements are included in the implanted chambers. Requirements for ossicle production were assessed in the model, including osteoprogenitor cells (donor bone marrow), osteoinductive signals (rhBMP2 or demineralized bone matrix), and osteoconductive matrix (Collagraft). Ossicle production required patency of the vascular pedicle, and for samples not containing cancellous isograft, donor marrow viability and an osteoinductive signal. Ossicles were produced without the need for an implanted osteoinductive matrix. Bone production and maturation time course were similar in chambers containing cancellous isograft, marrow/rhBMP2, and marrow/demineralized bone matrix. The demineralized bone matrix group had delayed early bone production, and the rhBMP2 group had lower final bone area. All groups had central osteolysis in the vascularized neo-ossicles. We believe the approach is promising for selected applications.

Histological evaluation of an impacted bone graft substitute composed of a combination of mineralized and demineralized allograft in a sheep vertebral bone defect

Demineralized bone matrix (DBMs) preparations are a potential alternative or supplement to autogenous bone graft, but many DBMs have not been adequately tested in clinically relevant animal models. The aim of current study was to compare the efficacy of a new bone graft substitute composed of a combination of mineralized and demineralized allograft, along with hyaluronic acid (AFT Bone Void Filler) with several other bone graft materials in a sheep vertebral bone void model. A drilled defect in the sheep vertebral body was filled with either the new DBM preparation, calcium sulfate (OsteoSet), autologous bone graft, or left empty. The sheep were euthanized after 6 or 12 weeks, and the defects were examined by histology and quantitative histomorphometry. The morphometry data were analyzed by one-way analysis of variance with the post hoc Tukey-Kramer test or the Student's t-test. All of the bone defects in the AFT DBM preparation group showed good new bone formation with variable amounts of residual DBM and mineralized bone graft. The DBM preparation group at 12 weeks contained significantly more new bone than the defects treated with calcium sulfate or left empty (respectively, p < 0.05, p < 0.01). There was no significant difference between the DBM and autograft groups. No adverse inflammatory reactions were associated with any of the three graft materials. The AFT preparation of a mixture of mineralized and demineralized allograft appears to be an effective autograft substitute as tested in this sheep vertebral bone void model.

Effectiveness of Local Antibiotic Delivery with an Osteoinductive and Osteoconductive Bone-Graft Substitute

The morbidity associated with open fractures and open fracture treatment is well established. An osteoinductive and osteoconductive bone-graft substitute that prevents infection would decrease the number of procedures required to treat contaminated fractures by eliminating the need for surgical removal of cement beads and perhaps autograft harvest. We hypothesized that the combination of tobramycin-impregnated calcium sulfate pellets and demineralized bone matrix would prevent the establishment of infection in a contaminated fracture model. A unicortical 12-mm-diameter defect was created in the proximal tibial metaphysis of twenty-nine Spanish goats. After contaminating the wounds with an infective dose of Staphylococcus aureus, we divided the animals into four groups. The negative control group received no treatment, the positive control group received tobramycin-impregnated polymethylmethacrylate beads, the demineralized bone matrix group received 2.5 mL of demineralized bone matrix, and the experimental group received tobramycin-impregnated calcium sulfate pellets with 2.5 mL of demineralized bone matrix. Radiographs were made and intraosseous tissue cultures were performed on postoperative day 21. The cultures showed no evidence of intramedullary infection in the experimental or the positive control group, but they were positive for Staphylococcus aureus in six of the seven goats in the negative control group and seven of the eight goats in the demineralized bone matrix group. The combination of tobramycin-impregnated calcium sulfate pellets and demineralized bone matrix was effective in preventing intramedullary Staphylococcus aureus infection in a contaminated goat fracture model.

Osteogenesis by guided tissue regeneration and demineralized bone matrix.

To evaluate in a discriminating capsule model whether bone formation by guided tissue regeneration (GTR) may be influenced by concomitant implantation of demineralized bone matrix (DBM). Thirty 4-month-old male albino rats of the Wistar strain were used in the study. Following surgical exposure of the mandibular ramus, a hemispherical, Teflon capsule (5.0 mm in diameter), loosely packed with a standardized amount of DBM, was placed with its open part facing the lateral bone surface of the ramus. At the contralateral side, an empty capsule was placed, serving as control. After healing periods of 15, 30, and 120 days, groups of 10 animals were sacrificed and 40-70 microm thick undecalcified sections of the capsules were produced. In the sections, the cross-sectional areas of (1) the space created by the capsule, (2) newly formed bone, (3) DBM particles, (4) loose connective tissue as well as the (5) height of the capsules, and (6) that of the newly formed bone were measured. Increasing bone fill was observed in both test and control sites from 30 to 120 days. After 30 days of healing, the mean amount of bone was approx. 3% of the cross-sectional area of the capsules at the test sites while it was 8% in the control sites (p<0.05). However, no statistically significant differences were observed between the test (46%) and control (64%) sites after 120 days regarding any of the measured parameters (p>0.05). The newly formed bone in the DBM group at 120 days, on the other hand, appeared more dense than that in the control capsules. DBM used as an adjunct to GTR did not provide any added effect on bone formation but increased the density of the newly formed bone.

Mechanical advantage of defects healed with demineralized bone matrix over autogenous bone graft

Purpose of study: The purpose of this investigation was to compare the mechanical stiffness and strength of healed, grafted defects using either the classical method of autogenous bone graft or demineralized bone matrix.Methods used: Critical 2-cm defects were created in the ulnas of 75 6-month-old male New Zealand White Rabbits (3.5 to 4.0 kg). Defects were treated with approximately 1 cc of graft material: demineralized bone matrix (DBM) plug, DBM + bone marrow (BM), devitalized DBM (dDBM), dDBM + BM, BM, empty or autogenous bone graft (ABG). Animals were radiographed at 0, 3, 6, 9 and at sacrifice at 12 weeks. Sixty-nine rabbits completed the study. The six deaths were the result of surgical complications. Only grafts that were graded as a union were mechanically tested. The radius transected and constructs were tested in torsion to failure. The torsional stiffness and maximum failure torque for each group were compared by analysis of variance with a pairwise comparison test using a Bonferroni adjustment.of findings: The radiographic findings at 12 weeks showed complete bridging of the defect in the DBM and DBM + BM groups. In contrast, healing was not as complete in the dDBM-treated defects. Defects treated with dDBM and bone marrow did considerably better. The BM group displayed complete bridging but without the uniform surface contour seen with the DBM groups. Defects treated with ABG were bridged, although difficult to analyze radiographically because of the endogenous mineral present within the graft. There was no statistical difference between the union rates except for the dDBM and empty groups. The torsional stiffness of the DBM + BM group was twice that of ABG (p<.01). There were no differences found in the maximum torque.Relationship between findings and existing knowledge: This study has shown that treatment of defects with a structural osteoinductive/osteoconductive scaffold, such as a DBM matrix plug in the presence of bone marrow, results in mechanically stronger bone at 12 weeks than defects treated with ABG alone. Although these results were obtained in a long bone model, they are consistent with Boden's results in a rabbit spine fusion model using structural DBM scaffolds and autograft, and suggest bone marrow would be useful adjunct in enhancing spine fusion.Overall significance of findings: In a clearly definable model, we were able to show superior material properties in comparison to the classical standard, ABG.Disclosures: No disclosures.Conflict of interest: Celeste Abjornson, grant research support; Joseph Lane, grant research support, Osteotech

Demineralized Bone Matrix as a Biological Scaffold for Bone Repair

Experimental models were created in rat fibula to represent impaired bone healing so that biological deficiencies that cause bone repair to fail or to be delayed may be investigated. These models consist of a 4-mm-long segmental defect, created in rat fibula by osteotomy, and fitted with a 7-mm-long tubular specimen of demineralized bone matrix (DBM) over the cut ends of the fibula. The experiments in this study involved various modifications of the DBM scaffold designed to reduce its osteoinductive activity: steam sterilization (sDBM), ethylene oxide sterilization (eoDBM), trypsin digestion (tDBM), and guanidine hydrochloride extraction (gDBM). Bone healing was evaluated by bending rigidity of the fibula and mineral content of the repair site at 7 weeks post-surgery. The sDBM scaffolds resorbed completely by 7 weeks and hence this model was a nonhealing negative control. Rigidities in the unmodified DBM and tDBM groups were comparable, whereas in the gDBM and eoDBM groups it was significantly reduced. Histologically, in the 4-mm defects repaired with unmodified DBM, direct and endochondral bone formation in the scaffold and the defect resulted in a neocortex consisting of woven and lamellar bone uniting the broken bone by 7 weeks post-surgery. We conclude that the eoDBM and gDBM groups represent failure or delay of the bone repair process when compared with the unmodified DBM group in which the process is analogous to normal bone healing.