Demineralized bone matrix for repair and regeneration of maxillofacial defects: A narrative review.

OBJECTIVES: Demineralized bone matrix (DBM) is a well-established bone graft material widely accepted by dentists and the public for its favorable osteoconductivity and osteoinductive potential. This article aimed to provide a narrative review of the current therapeutic applications and limitations of DBM in maxillofacial bone defects. STUDY SELECTION, DATA, AND SOURCES: Randomized controlled trials, prospective or retrospective clinical studies, case series and reports, and systematic reviews. MEDLINE, PubMed, and Google Scholar were searched using keywords. CONCLUSIONS: Some evidence supported the therapeutic application of DBM in periodontal intrabony defects, maxillary sinus lifts, ridge preservation, ridge augmentation, alveolar cleft repair, orthognathic surgery, and other regional maxillofacial bone defects. However, the limitations of DBM should be considered when using it, including potential low immunogenicity, instability of osteoinductive potential, handling of the graft material, and patient acceptance. CLINICAL SIGNIFICANCE: With the increasing demand for the treatment of maxillofacial bone defects, DBM is likely to play a greater role as a promising bone graft material. Safe and effective combination treatment strategies and how to maintain a stable osteoinductive potential will be the future challenges of DBM research.

Recombinant bone matrix maintains the graft space, induces vascularized bone regeneration and preserves canine tooth extraction socket structure.

AIM: Recombinant bone matrix (RBM) is a newly conceived and engineered porous bone graft granule of average size 600 µm composed of purified recombinant collagen peptide. We sought to examine the behaviour with time of RBM that was grafted in the canine tooth extraction socket. MATERIALS AND METHODS: The canine tooth extraction socket of the hemisectioned mandibular third premolar distal root was grafted with RBM granules, whereas the opposite side extraction socket served as non-grafted control. The mandibular samples were harvested at 1, 3 and 6 months of healing and subjected to micro-CT imaging and decalcified paraffin-embedded histology. Separately, the effect of RBM was compared with that of deproteinized cancellous bovine bone (DCBB) and bovine atelocollagen plug (BACP) in the canine tooth extraction model at 3 months of healing. RESULTS: RBM maintained the grafted space in the socket and the gingival connective tissue until new bone was formed within its porous space. The regenerated bone was highly vascularized and continued to mature, while RBM was completely bioresorbed by 6 months. The buccal and lingual alveolar ridge heights of the RBM-grafted extraction socket was better preserved than those of non-grafted control sockets. The degree of socket preservation by RBM was equivalent to that by DCBB, although their healing mechanisms were different. CONCLUSIONS: This study demonstrated that RBM induced controlled active bone regeneration and preserved the extraction socket structure in a canine model. Bioresorbable RBM engineered without animal or human source materials presents a novel bone graft category with robust bone regenerative property.

Subcutaneously Engineered Decalcified Bone Matrix Xenografts Promote Bone Repair by Regulating the Immune Microenvironment, Prevascularization, and Stem Cell Homing.

Immunoregulatory and vascularized microenvironments play an important role in bone regeneration; however, the precise regulation for vascularization and inflammatory reactions remains elusive during bone repair. In this study, by means of subcutaneous preimplantation, we successfully constructed demineralized bone matrix (DBM) grafts with immunoregulatory and vascularized microenvironments. According to the current results, at the early time points (days 1 and 3), subcutaneously implanted DBM grafts recruited a large number of pro-inflammatory M1 macrophages with positive expression of CD68 and iNOS, while at the later time points (days 7 and 14), these inflammatory cells gradually subsided, accompanying increased presence of anti-inflammatory M2 macrophages with positive expression of CD206 and Arg-1, indicating a gradually enhanced anti-inflammatory microenvironment. At the same time, the gradually increased angiogenesis was observed in the DBM grafts with implantation time. In addition, the positive cells of CD105, CD73, and CD90 were observed in the inner region of the DBM grafts, implying the homing of mesenchymal stem cells. The repair results of cranial bone defects in a rat model further confirmed that the subcutaneous DBM xenografts at 7 days significantly improved bone regeneration. In summary, we developed a simple and novel strategy for bone regeneration mediated by anti-inflammatory microenvironment, prevascularization, and endogenous stem cell homing.

Comparative Osteogenesis of Three Clinical Bone Graft Materials: An In Vivo Study.

PURPOSE: To investigate bone regeneration among three different bone graft materials in a rat calvarum model. MATERIALS AND METHODS: A total of 24 rats had two 5-mm defects placed per calvarial. Rats were divided into four groups: bovine xenograft (XG), demineralized bone matrix (DBM), mineralized bone graft (MBG), and collagen membrane control (CC). Within each group, samples were collected at two time points: 4 weeks (T4) and 8 weeks (T8). Bone regeneration was assessed by microcomputed tomography (micro-CT) imaging and was analyzed using MATLAB software. Additionally, the fixed samples were subsequently demineralized for immunohistochemistry and histomorphometry. Slides were mounted and stained with hematoxylin and eosin (H&E) stain as well as bone morphogenetic protein 2 (BMP-2) and runt-related transcription factor 2 (RUNX2) markers. The numbers of positive cells/area were calculated for each group and analyzed. RESULTS: At 4 weeks, DBM showed low mineral density (7.7%) compared to the control (25.2%), but increased dramatically at 8 weeks (DBM, T8 = 27.6%; CC, T8 = 27.2%). Xenograft material showed an increase in mineral desnity between T4 and T8 (XG, T4 = 25.0%; XG, T8 = 32.3%). MBG remained consistent over the 8-week trial period (MBG, T4 = 30.4%; MBG, T8 = 30.4%). BMP-2 expression was present in cells adherent to all graft materials. RUNX2 expression was also observed in cells adherent to all graft materials, indicating that during the 4- to 8-week healing period, all materials supported osteogenesis. CONCLUSIONS: Compared to other materials, the DBM had high osteoinductive properties during the 4- to 8-week time period based on increased mineral content. All materials were associated with immunohistologic evidence of osteogenesis in the rat calvarial defect model.

Comparison of demineralized bone matrix with different cycling crushing times in posterolateral fusion model of athymic rats.

Decalcified bone matrix (DBM) is a widely used alternative material for bone transplantation. In the DBM production process, an effective particle size and the highest utilization rate of raw materials can be achieved only through multiple high-speed circulating comminution. The rat posterolateral lumbar fusion model (PLF) is the most mature small animal model for the initial evaluation of the efficacy of graft materials for bone regeneration and spinal fusion. To evaluate the differences in the in vivo osteogenic effects of DBM pulverization through 1, 5, 9, and 14 high-speed cycles, sixty athymic rats were divided into six groups: single cycling crushing (CC1), 5 cycles of crushing (CC5), 9 cycles of crushing (CC9), 13 cycles of crushing (CC13), autogenous bone graft (ABG) and negative control (NC). Posterolateral lumbar fusion was performed. Six weeks after surgery, the bilateral lumbar fusion of athymic rats was evaluated through manual palpation, X-ray, micro-CT and histological sections. Rank data were tested by the rank-sum test, and nonparametric data were tested by the Kruskal‒Wallis H test. The manual palpation and X-ray results showed that the fusion rate did not significantly differ between the CC1, CC5, CC9, CC13 and ABG groups. However, cavities appeared in CC9 and CC13 on the micro-CT image. The bone mass (BV/TV) of CC1, CC5, CC9 and CC13 was better than that of the ABG group, while almost no osteogenesis was observed in the NC group. Histologically, there was no obvious difference between the four groups except that the CC9 group and CC13 group had more fibrous tissues in the new bone. In conclusion, DMB with different cycling crushing times has no obvious difference in fusion rate of PLF, but it is slightly better than the ABG group.

12-Month clinical and radiographic outcomes of ViBone viable bone matrix in patients undergoing cervical and lumbar spinal fusion surgery.

BACKGROUND: To investigate the clinical safety and efficacy of ViBone® Viable Bone Matrix (VBM), a next generation cellular bone matrix allograft that comprises all three essential bone-forming components: osteogenic, osteoinductive, and osteoconductive factors, and is optimized to enhance cell viability and bone formation. METHODS: This was a multi-center, prospective, post-market study evaluating the safety and efficacy of ViBone VBM in patients undergoing 1-3 level anterior cervical discectomy and fusion or lumbar interbody fusion surgery. Patients were evaluated at baseline, 6-month, and 12-month follow-up clinically and radiographically. Clinical assessment included Visual Analog Scale for pain (VAS-pain), the Neck Disability Index (NDI) for patients with cervical pathologies, and the Oswestry Disability Index (ODI) for patients with lumbar pathologies. Fusion success defined by an independent radiologist was determined radiographically by plain films. RESULTS: Clinical outcomes evaluated with VAS-pain, NDI, and ODI scales were improved significantly at 6 and 12 months compared to baseline. All patients reached clinically significant improvements at 12 months. There were no adverse events or infections attributed to ViBone VBM. At 12 months, the fusion rate per patient was 88.1% in cervical and 97.6% in lumbar patients, while per-level fusion was 98.5% for cervical and 100% for lumbar segments. CONCLUSIONS: Patients undergoing cervical and lumbar spinal fusion implanted with ViBone VBM demonstrated favorable outcomes at 6 months and 12 months as measured by subjective clinical measures and radiographic fusion rates. Trial registration This study was registered as NCT03425682 on 1/29/2018.

Relative influence on cell behaviors of osteoblasts seeded onto demineralized bone matrix with diverse particle size.

Demineralized bone matrix (DBM) is a natural and collagen-based allogeneic bone graft material with good bioactivity and biocompatibility. However, there are conflicting reports on the efficiency of this product owning to the relevant factors, especially, the particle size of DBM. In the current study, osteoblasts were seeded onto DBM with diverse particle sizes of 0.6-1.0 mm, 2.2-2.6 mm, 3.8-4.2 mm and 5.4-5.8 mm, and then the cell adhesion, proliferation, differentiation and apoptosis were analyzed to evaluate the effects of particle sizes on bioactivity and biocompatibility of DBM. It could be identified that particle size had a significant influence on the surface roughness and the collagen structure of DBM. In-vitro cytological assays had confirmed that DBM with all particle sizes had good cytocompatibility, which was beneficial for cell survival. What's more, DBM with a smaller particle size had a better biological activity and could promote cell proliferation and differentiation. We hope that researchers could choose to apply DBM with particle size of 0.6-1.0 mm for further intensive study, from which researchers will acquire more comparable and reliable conclusions for different study purposes.

Use of biphasic calcium phosphate versus demineralized bone matrix: retrospective clinical and CT analysis of posterolateral fusion results.

PURPOSE: Bone graft extenders have been developed to prevent donor site morbidity associated with iliac crest bone graft, but few studies compared the efficacy of various substitutes. Our purpose was to determine fusion rate and clinical outcome in patients undergoing lumbar arthrodesis using demineralized bone matrix (DBM) and biphasic calcium phosphate (BCP). METHODS: Patients with degenerative spondylolisthesis undergoing one-level or two-level arthrodesis of lumbar spine were retrospectively reviewed. Two treatment groups placed either BCP or DBM, in addition to local autograft in lumbar posterolateral space. Three-dimensional CT exam and dynamic flexion-extension radiographs at postoperative 2-year were assessed for posterolateral fusion status and pain scale and Oswestry Disability Index (ODI) for clinical outcome. RESULTS: Of the 148 patients reviewed (including 23 in one- and 58 patients in two-level in BCP group, and 47 in one- and 20 patients in two-level in DBM group), no significant differences were found in terms of age, sex, BMI, smoking, diabetes, steroids, number of level fused, non-union rate or revision surgery between BCP and DBM groups. Significantly improved pain scale of back and leg and ODI were found in both groups postoperatively without group difference. We found a comparable fusion rate in one-level surgery (100% versus 93.6%) and a superior fusion rate of BCP group in two-level surgery (98.3% versus 80.0%, p = 0.01). CONCLUSION: Being a bone graft extender without osteoinductive property, with local autograft, BCP is comparable to DBM for one- and superior for two-level fusion. No significant difference was found in clinical outcomes.

Histopathological and radiographical evaluation of caprine demineralized bone matrix in a critical ulnar defect in a rabbit model.

BACKGROUND: Caprine species satisfy the conditions of an ideal donor animal when compared to bovine species that has been extensively studied and commercialized for bone xenograft. Histopathological and radiological evaluations of caprine demineralized bone matrix (CDBM) were therefore carried out for fracture healing properties for its possible use in bone grafting procedures. MATERIALS AND METHODS: Twenty-four rabbits were used for this study and were divided randomly into three groups of eight (n = 8) rabbits each. Critical bone defect was created on the ulnar diaphysis under xylazine-ketamine anaesthesia for autogenous bone graft (ABG) group, CDBM group and the last group was left unfilled as negative control (NC). Immediate post-grafting radiograph was taken and repeated on days 14, 28, 42 and 56 to monitor the evidence of radiographic healing. The animals were euthanized on day 56 and defect sites were harvested for histopathology. RESULTS: There was a progressive evidence of radiographic healing and bone formation in all the groups with significance difference (P = 0.0064). When compared with ABG, NC differ significantly (P < 0.0001) whereas the CDBM did not differ significantly (P = 0.6765). The histopathology sections of ABG and CDBM showed normal bone tissue while the NC section was predominated by fibrous connective tissue. There was therefore an overall significant difference (P = 0.0001) in which CDBM did not differ from ABG (P = 0.2946) while NC did (P = 0.0005). CONCLUSION: The ABG and CDBM groups showed a similar healing effect in the critical bone defect. Therefore, CDBM could be used as an effective alternative to ABG in orthopaedics to circumvent the limitations and complications associated with it. LEVEL OF EVIDENCE: Not applicable.

The Multilayer GBR Technique: An Alternative Approach for One-Stage Transmucosal Implant Placement in the Presence of Horizontal Defects. A Case Series.

This study presents a one-stage technique for horizontal guided bone regeneration and transmucosal implant placement in the presence of hard and soft tissue defects. The proposed technique uses autologous bone particles, deproteinized bovine bone matrix, collagen membranes, and concentrated growth factor membranes to create a multilayer barrier and enhance tissue regeneration. Four patients were treated with a total of seven implants. Digital analyses of intraoral scan data taken at baseline and at 6 months postsurgery showed a mean increase in tissue volume of 157.4 mm3. The patient satisfaction was high, and no complications were observed.

Bone Graft Options in Spinal Fusion: A Review of Current Options and the Use of Mesenchymal Cellular Bone Matrices.

BACKGROUND: Spinal fusion is the mainstay treatment for various spinal conditions ranging from lumbar and cervical stenosis to degenerative spondylolisthesis as well as extensive deformity corrections. A new emerging category of allograft is cellular bone matrices (CBMs), which take allogeneic mesenchymal stem cells and incorporate them into an osteoconductive and osteoinductive matrix. This study reviewed the current spinal fusion options and new emerging treatment options. METHODS: Articles were searched using PubMed. The search included English publications since January 1, 2014, using the search terms "cellular bone matrix," "mesenchymal stem cells spinal fusion," "spinal arthrodesis AND mesenchymal stem cells," and "spine fusion AND cellular bone matrix." RESULTS: Spinal fusion is accomplished through the use of allografts, autografts, and bone graft substitutes in combination or alone. An emerging category of allograft is CBMs, in which an osteoconductive and osteoinductive matrix is filled with mesenchymal stem cells. Studies demonstrate that CBMs have achieved equivalent or better fusion rates compared with traditional options for anterior cervical discectomy and fusions and posterolateral lumbar fusions; however, the studies have been retrospective and lacking control groups and therefore not ideal. CONCLUSIONS: Many treatment options have been successfully used in spinal fusion. Newer allografts such as CBMs have shown promising results in both animal and clinical studies. Further research is needed to determine the therapeutic dose of mesenchymal stem cells delivered within CBMs.

Comparative Assessment of Autogenous Cancellous Bone Graft and Bovine-Derived Demineralized Bone Matrix for Secondary Alveolar Bone Grafting in Patients With Unilateral Cleft Lip and Palate.

OBJECTIVE: Comparison between bovine-derived demineralized bone matrix (DMBM) and iliac crest graft over long term for secondary alveolar bone grafting (SABG) in patients with unilateral cleft lip and palate (UCLP) in terms of radiological and clinical outcomes. DESIGN: Prospective, randomized, parallel groups, double-blind, controlled trial. SETTING: Unit of Oral and Maxillofacial Surgery, Oral Health Science Centre, Postgraduate Institute of Medical Education & Research, Chandigarh. PARTICIPANTS: Twenty patients with UCLP. INTERVENTIONS: Patients were allocated into group I (Iliac crest bone graft) and group II (DMBM) for SABG. Outcomes were assessed at 2 weeks, 6 months, and then after mean follow-up period of 63 months. OUTCOMES MEASURES: Volumetric analysis of the grafted bone in the alveolar cleft site was done through cone beam computed tomography using Cavalieri principle and modified assessment tool. Clinical assessment was performed in terms of pain, swelling, duration of hospital stay, cost of surgery, alar base symmetry, and donor site morbidity associated with iliac crest harvesting. RESULTS: Volumetric analysis through Cavalieri principle revealed comparable bone uptake at follow-up of 6 months between group I (70%) and group II (69%). Modified assessment tool showed no significant difference between horizontal and vertical bone scores over short- and long-term follow-up. In group II, there was higher cost of surgery, but no donor site morbidity unlike group I. CONCLUSIONS: Demineralized bone matrix proved analogous to iliac crest bone graft as per volumetric analysis over shorter period. However, although statistically insignificant, net bone volume achieved was lower than the iliac crest graft at longer follow-up.

Treatment of En Coup de Sabre Deformity with Fat Grafting and Demineralized Bone Matrix: A Case Series.

En coup de sabre deformity (ECDS) is a form of localized scleroderma in the frontoparietal region caused by progressive subcutaneous tissue atrophy and bony defect. Although ECDS involves two layers, skin/subcutaneous tissue and bone, the existing literature mainly focuses only on treating the skin/subcutaneous tissue layer. In this case series, we aimed to propose a novel approach that includes the combined use of fat grafting and demineralized bone matrix (DBM). Four patients with ECDS deformity, operated between February 2016 and October 2018, were retrospectively evaluated. All the patients were treated with the novel approach. Patients were evaluated with localized scleroderma scale and computed tomography (CT) scan in the preoperative period and at the annual follow-up. We observed remarkable improvement in the localized scleroderma scale including appearance, palpation, and size scores in all patients at the annual follow-up. CT scans at the annual follow-up revealed new callus formation at the bony defect area in all patients. Reinforcing fat grafting with DBM could promote healing of the bony and skin/subcutaneous tissue defects associated with ECDS.

Fibrous Demineralized Bone Matrix (DBM) Improves Bone Marrow Mononuclear Cell (BMC)-Supported Bone Healing in Large Femoral Bone Defects in Rats.

Regeneration of large bone defects is a major objective in trauma surgery. Bone marrow mononuclear cell (BMC)-supported bone healing was shown to be efficient after immobilization on a scaffold. We hypothesized that fibrous demineralized bone matrix (DBM) in various forms with BMCs is superior to granular DBM. A total of 65 male SD rats were assigned to five treatment groups: syngenic cancellous bone (SCB), fibrous demineralized bone matrix (f-DBM), fibrous demineralized bone matrix densely packed (f-DBM 120%), DBM granules (GDBM) and DBM granules 5% calcium phosphate (GDBM5%Ca2+). BMCs from donor rats were combined with different scaffolds and placed into 5 mm femoral bone defects. After 8 weeks, bone mineral density (BMD), biomechanical stability and histology were assessed. Similar biomechanical properties of f-DBM and SCB defects were observed. Similar bone and cartilage formation was found in all groups, but a significantly bigger residual defect size was found in GDBM. High bone healing scores were found in f-DBM (25) and SCB (25). The application of DBM in fiber form combined with the application of BMCs shows promising results comparable to the gold standard, syngenic cancellous bone. Denser packing of fibers or higher amount of calcium phosphate has no positive effect.

Improved osteogenesis in rat femur segmental defects treated with human allograft and zinc adjuvants.

Bone allograft is widely used to treat large bone defects or complex fractures. However, processing methods can significantly compromise allograft osteogenic activity. Adjuvants that can restore the osteogenic activity of processed allograft should improve clinical outcomes. In this study, zinc was tested as an adjuvant to increase the osteogenic activity of human allograft in a Rag2 null rat femoral defect model. Femoral defects were treated with human demineralized bone matrix (DBM) mixed with carboxy methyl cellulose containing ZnCl2 (0, 75, 150, 300 µg) or Zn stearate (347 µg). Rat femur defects treated with DBM-ZnCl2 (75 µg) and DBM-Zn stearate (347 µg) showed increased calcified tissue in the defect site compared to DBM alone. Radiograph scoring and µCT (microcomputed tomography) analysis showed an increased amount of bone formation at the defects treated with DBM-Zn stearate. Use of zinc as an adjuvant was also tested using human cancellous bone chips. The bone chips were soaked in ZnCl2 solutions before being added to defect sites. Zn adsorbed onto the chips in a time- and concentration-dependent manner. Rat femur defects treated with Zn-bound bone chips had more new bone in the defects based on µCT and histomorphometric analyses. The results indicate that zinc supplementation of human bone allograft improves allograft osteogenic activity in the rat femur defect model.

A partially demineralized allogeneic bone graft: in vitro osteogenic potential and preclinical evaluation in two different intramembranous bone healing models.

In skeletal surgical procedures, bone regeneration in irregular and hard-to-reach areas may present clinical challenges. In order to overcome the limitations of traditional autologous bone grafts and bone substitutes, an extrudable and easy-to-handle innovative partially demineralized allogenic bone graft in the form of a paste has been developed. In this study, the regenerative potential of this paste was assessed and compared to its clinically used precursor form allogenic bone particles. Compared to the particular bone graft, the bone paste allowed better attachment of human mesenchymal stromal cells and their commitment towards the osteoblastic lineage, and it induced a pro-regenerative phenotype of human monocytes/macrophages. The bone paste also supported bone healing in vivo in a guide bone regeneration model and, more interestingly, exhibited a substantial bone-forming ability when implanted in a critical-size defect model in rat calvaria. Thus, these findings indicate that this novel partially demineralized allogeneic bone paste that combines substantial bone healing properties and rapid and ease-of-use may be a promising alternative to allogeneic bone grafts for bone regeneration in several clinical contexts of oral and maxillofacial bone grafting.

Is percutaneous injection of bone marrow concentrate, demineralized bone matrix and PRF an alternative to curettage and bone grafting for treating aneurysmal bone cyst?

To determine the efficacy and safety of a single injection with autologous bone marrow concentrate (BMC) combined with demineralized bone matrix (DBM) and platelet-rich fibrin (PRF) compared to curettage and bone grafting for treating aneurysmal bone cysts (ABC). Two hundred thirty-nine patients were treated with curettage and bone grafting (Curettage Group), and 21 with percutaneous injection of DBM associated with autologous BMC and PRF (DBM + BMC + PRF Group). All patients attended the outpatient clinic to assess ABC healing and clinical results at the first 3, 6, 9 and 18 months after surgery and then annually in the absence of symptoms. The mean follow-up was 42 months for the Curettage Group (range 6-180 months) and 28 months for the DBM + BMC + PRF Group (range, 6-85 months). Out of the 21 patients who had injection with BMC, DBM, and PRF, 17 (80%) require no additional treatment and they were considered healed. Of the 239 patients treated with curettage and bone grafting after core needle or open biopsy, 177 (74%) were considered healed after the first treatment. Injection in comparison with curettage presented the same risk for local recurrence. The overall rate of local recurrence for all patients was 25%. Univariate and multivariate analyses showed a significant difference in local recurrence rates in patients younger than 15 years, and for the cyst located in the long bones of the lower limbs than the cyst located in the long bones of the upper limbs.

Evaluation of Demineralized Bone Matrix Particles Delivered by Alginate Hydrogel for a Bone Graft Substitute: An Animal Experimental Study.

BACKGROUND Our objective was to explore a synthetic alginate hydrogel delivery system for the delivery of demineralized bone matrix (DBM) particles for bone graft substitutes. MATERIAL AND METHODS The physiochemical properties of surface morphology, porosity measurements, in vitro degradation, equilibrium swelling, and mechanical testing of combined DBM powder and alginate in amounts of 0 mg/1 mL, 25 mg/1 mL, 50 mg/1 mL, and 100 mg/1 mL were detected. In vitro cell culture and in vivo studies using Sprague-Dawley rats were performed to evaluate the biocompatibility and osteoinductivity of DBM-alginate (ADBM) composites. RESULTS DBM particles were uniformly scattered in all composites, and macro-scale pores were omnipresent. All composites showed a similar low degradation rate, with approximately 85% of weight remaining after 15 days. As the concentration of DBM particles in composites increased, degradation in collagenase and elastic modulus increased and the pore area and swelling ratio significantly decreased. No cytotoxicity of ADBM or alginate on mesenchymal stem cells (MSCs) was observed. Cell cultivation with ADBM showed greater osteogenic potential, evidenced by the upregulation of alkaline phosphatase and alizarin red staining activity and the mRNA expression level of marker genes RUNX2, OCN, OPN, and collagen I compared with the cells grown in alginate. Evaluation of ectopic bone formation revealed the osteoinductivity of the ADBM composites was significantly greater than that of DBM particles. Osteoinduction of the composites was demonstrated by a cranial defect model study. CONCLUSIONS The delivery of DBM particles using a synthetic alginate hydrogel carrier may be a promising approach in bone tissue engineering for bone defects.

Single Layer Biomaterial Repair of Frontal Sinus Encephalocele in a Pediatric Patient.

INTRODUCTION: Reconstruction of skull base defects are determined by size, location, and complexity of the defect. METHODS: Case report. CASE DISCUSSION: An 11-year old girl presented with a right frontoethmoidal encephalocele after an episode of meningitis. An endoscopic approach was performed with a Draf III to provide exposure. The skull base defect extended superolateral over the orbit, which limited the choice of reconstructive options. The defect was successfully repaired with a single layer onlay graft of bovine collagen matrix. CONCLUSIONS: Single layer repairs using commercial biomaterials should be considered where multilayer closure or vascularized flaps may not be possible. Laryngoscope, 131:E1750-E1752, 2021.

Early to medium term outcomes of osteochondral lesions of the talus treated by autologous matrix induced chondrogenesis (AMIC).

BACKGROUND: The primary aim of the study is to evaluate the functional outcome following AMIC procedure in patients with osteochondral injury of the talus. The secondary aim is to evaluate if size of the lesion and patient's age influence outcome. MATERIALS AND METHODS: This is a retrospective study of 25 patients who underwent AMIC procedure of the talus treated by a single surgeon. Functional outcomes were evaluated using pre and post operative AOFAS and VAS scores. RESULTS: The mean lesion size was 1.74 cms with 88% of lesions in the study more than 1.4 cms. There was a significant improvement in AOFAS score with mean improvement of 49.40 (p < 0.05) and VAS score of 5.36 (p < 0.05). We could not find any correlation between either age or lesion size with functional outcome for AMIC procedure. CONCLUSION: AMIC procedure seems to be a reliable treatment method for larger diameter osteochondral lesions of the talus up to 2.5 cms in diameter.