Demineralized bone matrix and spinal arthrodesis

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.

Fusion rates based on type of bone graft substitute using minimally invasive scoliosis surgery for adolescent idiopathic scoliosis

BACKGROUND

Minimally invasive scoliosis surgery (MISS) is currently introduced on novel technique for surgical treatment of adolescent idiopathic scoliosis (AIS). This study is aimed to evaluate the efficacy of facet fusion in MISS compared to posterior fusion in conventional open scoliosis surgery (COSS) and compare facet fusion rates based on three bone graft substitutes in MISS for adolescent idiopathic scoliosis (AIS).

METHODS

Eighty six AIS patients who underwent scoliosis surgery were divided into two groups: the COSS group and the MISS group. COSS was performed through posterior fusion with allograft. MISS was applied via facet fusion with three bone graft substitutes. The MISS group was further divided into three subgroups based on graft substitute: Group A (allograft), Group B (demineralized bone matrix [DBM]), and group C (demineralized cancellous bone chips). Fusion rate was measured using conventional radiographs to visualize loss of correction > 10°, presence of lysis around implants, breaks in fusion mass, and abnormal mobility of the fused segment.

RESULTS

The fusion rates showed no significant difference in COSS and MISS groups (p = 0.070). In the MISS group, the fusion rates were 85, 100, and 100% in groups A, B, and C, respectively, with no significant difference (p = 0.221). There were no statistical differences between groups A, B, and C in terms of correction rate, fusion rate, and SRS-22 scores (p > 0.05).

CONCLUSIONS

The facet fusion in MISS showed comparable to posterior fusion in COSS with regard to radiological and clinical outcomes. Furthermore, the type of graft substitute among allograft, DBM, and demineralized cancellous bone chips did not affect facet fusion rate or clinical outcomes in MISS. Therefore, MISS showed comparable fusion rate (with no influences on the type of graft substitute) and clinical outcomes to those of COSS in the surgical treatment of AIS.

Use of demineralized cortical fibers is associated with reduced risk of pseudarthrosis after pedicle subtraction osteotomy for adult spinal deformity

PURPOSE

To assess the effect of demineralized cortical fibers (DCF) on postoperative pseudarthrosis requiring revision surgery in patients undergoing pedicle subtraction osteotomy (PSO) for adult spinal deformity (ASD).

METHODS

The use of DCF was introduced across all procedures in 2017 and subsequent patients undergoing PSO surgery were prospectively and consecutively registered. Following sample-size estimation, a retrospective cohort was also registered undergoing the same procedure immediately prior to the implementation of DCF. The non-DCF group underwent surgery with ABG. Minimum follow-up was 2 years in both groups. The main outcome was postoperative pseudarthrosis, either CT-verified or verified intraoperatively during revision surgery due to rod breakage and assessed using Kaplan-Meier survival analyses.

RESULTS

A total of 48 patients were included in the DCF group and 76 in the non-DCF group. The DCF group had more frequently undergone previous spine surgery (60% vs 36%) and had shorter follow-up (32 ± 2 vs 40 ± 7 months). Pseudarthrosis occurred in 7 (15%) patients in the DCF group and 31 (41%) in the non-DCF group, corresponding to a relative risk increase of 2.6 (95%CI 1.3-2.4, P < 0.01). 1-KM survival analyses, taking time to event into account and thus the difference in follow-up, also showed increased pseudarthrosis in the non-DCF group (log-rank P = 0.022). Similarly, multivariate logistic regression adjusted for age, instrumented levels and sacral fusion was also with significantly increased odds of pseudarthrosis in the non-DCF group (OR: 4.3, 95%CI: 1.7-11.3, P < 0.01).

CONCLUSION

We found considerable and significant reductions in pseudarthrosis following PSO surgery with DCF compared to non-DCF.

LEVEL OF EVIDENCE

III.

Novel Approaches Guiding the Future of Spinal Biologics for Bone Regeneration

Purpose of Review

Despite the continued growth of spine fusion procedures, the ideal material for bone regeneration remains unclear. Current bone graft substitutes and extenders in use such as exogenous BMP-2 or demineralized bone matrix and hydroxyapatite either have serious complications associated with use or lead to clinically significant rates of non-union. The introduction of nanotechnology and 3D printing to regenerative medicine facilitates the development of safer and more efficacious bone regenerative scaffolds that present solutions to these problems. Many researchers in orthopedics recognize the importance of lowering the dose of recombinant growth factors like BMP-2 to avoid the complications associated with its normal required supraphysiologic dosing to achieve high rates of fusion in spine surgery.

Recent Findings

Recent iterations of bioactive scaffolds have moved towards peptide amphiphiles that bind endogenous osteoinductive growth factor sources at the site of implantation. These molecules have been shown to provide a highly fluid, natural mimetic of natural extracellular matrix to achieve 100% fusion rates at 10–100 times lower doses of BMP-2 relative to controls in pre-clinical animal posterolateral fusion models. Alternative approaches to bone regeneration include the combination of existing natural growth factor sources like human bone combined with bioactive, biocompatible components like hydroxyapatite using 3D-printing technologies. Their elastomeric, 3D-printed scaffolds demonstrate an optimal safety profile and high rates of fusion (~92%) in the rat posterolateral fusion model.

Summary

Bioactive peptide amphiphiles and developments in 3D printing offer the promising future of a recombinant growth factor- free bone graft substitute with similar efficacy but improved safety profiles compared to existing bone graft substitutes.

Comparison of demineralized bone matrix and hydroxyapatite as carriers of Escherichia coli recombinant human BMP-2

Background

Autograft has been widely used in various orthopedic and dental surgery for its superior osteogenicity, osteoinductivity and osteoconductivity. But the available volume of the autograft is limited and the efficacy of it is highly affected by the condition of the patients. Therefore, growth factors such as Escherichia coli bone morphogenetic protein-2 (ErhBMP-2) has been widely used in some countries and regions with various carriers that could affect the effects of the growth factors. Demineralized bone matrix (DBM) has been widely used as a bone graft substitute and growth factor carrier, but its effect as a carrier of ErhBMP-2 was less investigated.

Materials and methods

Rat calvaria defect model was used in this study. We implanted ErhBMP-2 with DBM or hydroxyapatite (HA) as a carrier in 8 mm calvaria defect and compared their bone regeneration effect in 4th week and 8th week after implantation with micro-CT and histology. The data was analyzed with one-way ANOVA method with Bonferroni post-hoc analysis.

Result

The group with DBM as the carrier showed significantly higher bone volume and bone thickness than the groups with HA as the carrier in both weeks. And the histology sections showed less adipose tissue formed in the groups with DBM as the carrier.

Conclusion

DBM could be a better carrier for ErhBMP-2 than HA.

Osteoformation potential of an allogenic partially demineralized bone matrix in critical-size defects in the rat calvarium

Allogenic demineralized bone matrix has been developed as a reliable alternative to the autologous bone graft. In the present study, we assessed the osteoformation potential of a partially demineralized bone matrix (PDBM) in a paste form obtained without an added carrier. This formulation included the preparation of cancelous bone from femoral heads after decellularision, delipidation, demineralization in HCl and autoclaving at 121 °C. Structural and biochemical characteristics of PDBM were determined using FTIR (Fourier transform infrared spectroscopy), hydroxyproline, DNA content assays, and optical ellipsometry. The osteoformation potential was evaluated in 8-, 6-, and 4-mm-diameter rat-calvarial bone defects by in vivo micro-CT analysis, performed immediately after surgery on days 0, 15, 30, 45, and 60. Moreover, histological and histomorphometric analyses were done on day 60. PDBM was compared to cancelous bone powder (BP) before its partial demineralization. The expression levels of selected inflammation-, angiogenesis-, and bone-related genes were also investigated by RT-PCR, 3, 7, and 14 days after surgery. Compared to the control group, the PDBM group exhibited a significant increase (p < 0.05) in radiopacity in 8-mm- and 6-mm-diameter defects at all time points tested. On day 60, the amount of newly-formed bone was greater (16 and 1.6 folds; p < 0.001; respectively) compared to that in control defects. No bone formation was observed in defects filled with BP regardeless of the size. In 8-mm-diameter defect, PDBM was effective enough to induce the upregulation of genes pertinent to inflammation (i.e., TNFα, IL-6, and IL-8), angiogenesis (i.e., VEGF, VWF), and osteogenesis (ALP, RUNX2, BGLAP, SP7) by day 3 after surgery. This study showed that the tested PDBM deeply influences the early critical events involved in bone regeneration and exhibits efficient osteoformation capacity, making it an attractive graft option for treating defects in periodontal and maxillofacial areas.

Understanding the Future Prospects of Synergizing Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery with Ceramics and Regenerative Cellular Therapies

Transforaminal lumber interbody fusion (TLIF) is the last resort to address the lumber degenerative disorders such as spondylolisthesis, causing lower back pain. The current surgical intervention for these abnormalities includes open TLIF. However, in recent years, minimally invasive TLIF (MIS-TLIF) has gained a high momentum, as it could minimize the risk of infection, blood loss, and post-operative complications pertaining to fusion surgery. Further advancement in visualizing and guiding techniques along with grafting cage and materials are continuously improving the safety and efficacy of MIS-TLIF. These assistive techniques are also playing a crucial role to increase and improve the learning curve of surgeons. However, achieving an appropriate output through TLIF still remains a challenge, which might be synergized through 3D-printing and tissue engineering-based regenerative therapy. Owing to their differentiation potential, biomaterials such as stem/progenitor cells may contribute to restructuring lost or damaged tissues during MIS-TLIF, and this therapeutic efficacy could be further supplemented by platelet-derived biomaterials, leading to improved clinical outcomes. Thus, based on the above-mentioned strategies, we have comprehensively summarized recent developments in MIS-TLIF and its possible combinatorial regenerative therapies for rapid and long-term relief.

In-vivo Performance of Seven Commercially Available Demineralized Bone Matrix Fiber and Putty Products in a Rat Posterolateral Fusion Model

Introduction: Demineralized bone matrix (DBM) is a widely used bone graft in spinal fusion. Most commercial DBMs are composed of demineralized bone particles (~125–800 microns) suspended in a carrier that provides improved handling but dilutes the osteoinductive component. DBM fibers (DBF) provide improved osteoconductivity and do not require a carrier. It has been suggested that 100% DBF may offer improved performance over particulate-based DBMs with carrier.

Study Design: Seven commercially available DBM products were tested in an athymic rat posterolateral fusion model. There were four 100% DBFs, two DBFs containing a carrier, and one particulate-based DBM containing carrier.

Objective: The study objectives were to evaluate the in vivo performance: (1) compare fusion rate and fusion maturity of six commercially available DBFs and one particulate-based DBM, and (2) assess the effect of carrier on fusion outcomes for DBFs in a posterolateral fusion model.

Methods: The DBF/DBM products evaluated were: Strand^TM Family, Propel® DBM Fibers, Vesuvius® Demineralized Fibers, Optium® DBM Putty, Grafton® DBF, Grafton Flex, and DBX® Putty. Single-level posterolateral fusion was performed in 69 athymic rats. Fusion was assessed bilaterally after 4 weeks by manual palpation, radiograph and CT for bridging bone. Fusion mass maturity was assessed with a CT maturity grading scale and by histology. Statistical analysis was performed using Fishers Exact Test for categorical data and Kruskal-Wallis Test for non-parametric data.

Results: Strand Family achieved 100% fusion (18/18) by manual palpation, radiographic and CT evaluation, significantly higher than Propel Fibers, Vesuvius Fibers, Optium Putty, and DBX Putty, and not statistically higher than Grafton DBF and Grafton Flex. Strand Family provided the highest fusion maturity, with CT maturity grade of 2.3/3.0 and 89% mature fusion rate. Fusion results suggest a detrimental effect of carrier on fusion performance.

Conclusions: There were large variations in fusion performance for seven commercially available DBM products in an established preclinical fusion model. There were even significant differences between different 100% DBF products, suggesting that composition alone does not guarantee in vivo performance. In the absence of definitive clinical evidence, surgeons should carefully consider available data in valid animal models when selecting demineralized allograft options.

Effect of Trabecular Microstructure of Spinous Process on Spinal Fusion and Clinical Outcomes After Posterior Lumbar Interbody Fusion: Bone Surface/Total Volume as Independent Favorable Indicator for Fusion Success

OBJECTIVE

We assessed the trabecular microarchitecture of the spinous process as an autograft and investigated its correlations with fusion success and clinical outcomes for patients undergoing posterior lumbar interbody fusion.

METHODS

Micro-computed tomography reconstruction techniques were used to scan cancellous bone specimens from spinous processes. We then measured the microarchitectural parameters for 105 subjects.

RESULTS

The patient cohort included 44 older men and 61 postmenopausal women with a minimum of 2-year follow-up data available. The complete fusion rate was 87.6% (92 of 105) at the last follow-up. When stratified by fusion status, the union group had significantly greater bone surface/total volume (BS/TV) and trabecular number but significantly lower trabecular separation than the nonunion group. No statistically significant differences were observed between the 2 groups in the clinical variables, except for the bone mineral density at the femoral neck (P = 0.028). On binomial logistic regression analysis, BS/TV was identified as an independent predictor for fusion success (odds ratio, 8.532; P = 0.032). The receiver operating characteristic curve showed that BS/TV had excellent performance in predicting successful fusion (area under the curve, 0.807). Using a cutoff value for BS/TV of 3.145, a greater BS/TV was significantly associated with visual analog scale scores for lower back pain 6 months postoperatively and lower Oswestry disability index scores at 12 and 24 months postoperatively but not with visual analog scale scores for leg pain.

CONCLUSIONS

Our data suggest that microstructural deterioration of the spinal process as an autograft has detrimental effects on spinal fusion and clinical outcomes for patients undergoing instrumented posterior lumbar interbody fusion. Specifically, the microstructural parameter BS/TV has good potential for assessing lumbar bone quality and predicting fusion success.

An evaluation of biomaterials and osteobiologics for arthrodesis achievement in spine surgery

An increasing variety of orthobiologic materials, including autologous and allogeneic bone graft, bone marrow aspirate, demineralized bone matrix, ceramics, and growth factors are available to the spine surgeon. Although autologous bone graft remains the gold standard material, concerns for failure in achieving fusion have prompted evaluation of current and new biologic materials. As such, this review attempts to summarize the available biologic materials with their pertinent characteristics, advantages, disadvantages, and primary uses.

Orthobiologics in minimally invasive lumbar fusion

Minimally invasive (MI) spine surgery continues to gain popularity with patients and surgeons for its potential to decrease operative time and avoid complications commonly associated with open surgery. In the face of a changing surgical landscape, selecting the appropriate implant material to be used in MI lumbar fusion procedures will remain critically important. Various orthobiologic materials are available for use, including autologous and allogeneic bone graft, bone marrow aspirate (BMA), demineralized bone matrix (DBM), ceramics, and growth factors. The purpose of this review is to summarize the use and efficacy of currently available products, as well as highlight the development of novel therapeutic options.

Escherichia coli BMP-2 showed comparable osteoinductivity with Chinese hamster ovary derived BMP-2 with demineralized bone matrix as carrier

Escherichia coli bone morphogenetic protein-2 (ErhBMP-2) had a larger yield but less osteoinductivity than Chinese hamster ovary cell bone morphogenetic protein-2 (CrhBMP-2). Since the release profile of rhBMP-2 affects its osteoinductivity, an appropriate carrier could improve the effect of ErhBMP-2. Demineralized bone matrix (DBM) was one of the most widely used bone substitutes, but few studies evaluated the osteoinductivity of ErhBMP-2 while it was carried by DBM. Therefore, we compared the osteoinductivity of ErhBMP-2 with CrhBMP-2 with DBM as the carrier of each. In vitro results showed ErhBMP-2 had slightly less osteoinductivity than CrhBMP-2. However, with DBM as the carrier, ErhBMP-2 induced significantly more bone regeneration in rat calvaria defects. Therefore, ErhBMP-2 might have comparable osteoinductivity with CrhBMP-2 while carried by DBM.

[Demineralized cancellous bone seeded with allogeneic chondrocytes for repairing articular osteochondral defects in rabbits]

OBJECTIVE

To evaluate the effect of demineralized cancellous bone (DCB) seeded with allogeneic chondrocytes for repairing articular osteochondral defects in rabbits.

METHODS

Articular chondrocytes were isolated from a 1-month-old male New Zealand rabbit for primary culture. The passage 1 chondrocytes were seeded onto prepared rabbit DCB scaffold to construct tissue-engineered cartilage and cultured in vitro for 2 weeks. Full-thickness articular osteochondral defects (3 mm both in diameter and depth) were created on both sides of the femoral medial condyles in 30 New Zealand white rabbits (age 4- 5 months). In 20 of the rabbits, the defects were filled with the tissue-engineered cartilage on the right side (group A) and with DCB only on the left side (group B); the remaining 10 rabbits did not receive any implantation in the defects to serve as the control (group C). At 1, 3, and 6 months after the implantation, tissue samples were collected from the defects for macroscopic observation and histological examination with Toluidine blue (TB) and collagen type Ⅱ staining. The effect of defect repair using the tissue-engineered cartilage was assessed at 6 months based on the histological scores.

RESULTS

The prepared DCB had a spongy 3D structure with open and interconnected micropores of various sizes and showed good plasticity and mechanical strength. DCB began to degrade within 1 month after implantation and was totally absorbed at 3 months. At 6 months after implantation, the defects filled with the chondrocyte-seeded DCB were repaired mainly by hyaline-like cartilage tissues, which were well integrated to the adjacent cartilage without clear boundaries and difficult to recognize. The chondrocytes were located in the lacunate and arranged in vertical columns in the deep repaired tissue, where matrix proteoglycans and collagen type Ⅱ were distributed homogeneously close to the normal cartilage. The subchondral bone plate was reconstructed completely. The defects implanted with DCB only were filled with fibrocartilage tissue, as compared with fibrous tissue in the control defects. The histological scores in group A were significantly superior to those in group B and C (P < 0.05), but the scores for subchondral bone plate reconstruction were comparable between groups A and B at 6 months.

CONCLUSIONS

DCB is a good scaffold material for preparing tissue-engineered cartilage, and chondrocyte- seeded DCB can repair articular osteochondral defects by inducing the generation of hayline-like cartilage.

Histological Evaluation of the Healing Process of Various Bone Graft Materials after Engraftment into the Human Body

The purpose of this study was to measure the level of new bone formation induced by various bone graft materials to provide clinicians with more choices. The samples were divided into three groups: group 1 (n = 9: allograft + xenograft, DBX^®, San Francisco, CA, USA + Bio-Oss^®, Princeton, NJ, USA), group 2 (n = 10: xenograft, Bio-Oss^®), and group 3 (n = 8: autogenous tooth bone graft, AutoBT^®, Korea Tooth Bank, Seoul, Korea). The average duration of evaluation was 9.56, 2.50, and 3.38 months, respectively. A tissue sample was taken from 27 patients during the second implant surgery. New bone formation was measured via histomorphometry, using a charge-coupled device camera, adaptor, and image analysis software. Total bone area, total area, and ((total bone area/total area) × 100) was measured to determine the extent of new bone formation. The mean value of the total bone area was 152,232.63 μm²; the mean value of the total area was 1,153,696.46 μm²; and the mean total bone area/total area ratio was 13.50%. In each comparison, there was no significant difference among the groups; no inflammation or complications were found in any of the groups. AutoBT^®, an autogenous tooth bone graft, resulted in a level of bone formation similar to that using allografts and xenografts.

The Poor Osteoinductive Capability of Human Acellular Bone Matrix

Demineralized bone matrix (DBM) has extensive clinical use for bone regeneration because of its osteoinductive and osteoconductive aptitude. It is suggested that the demineralization process in bone matrix preparation is influential in maintaining osteoinductivity; however, relevant investigations, especially into the osteoinductivity of acellular bone matrix, are not often performed. This study addressed the osteoinductive capability of human acellular cancellous bone matrix (ACBM) after subcutaneous implantation in a rat model. The growth and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBM-MSCs) seeded in this material were also studied. Without the demineralization process, the ACBM we obtained had an interconnected porous network and the micropores in the surface were clearly exposed. After the ACBM was subcutaneously implanted for 4 months, new osteoid formation was noted but not typical mature bone formation. rBM-MSCs grew well in the ACBM and kept a steady morphology after continuous culture for 28 days. However, no mineralized nodule formation was detected and the expression levels of genes encoding osteogenic markers were significantly decreased. These results demonstrated that human ACBM possess the structural features of native bone and poor osteoinductivity; nonetheless this material helped to preserve the undifferentiated phenotype of rBM-MSCs. Such insights may further broaden our understanding of the application of ACBM for bone regeneration and the creation of stem cell niches.

Biomimetic matrix fabricated by LMP-1 gene-transduced MC3T3-E1 cells for bone regeneration

Bone healing is regulated by multiple microenvironmental signals provided by the extracellular matrix (ECM). This study aimed to mimic the native osteoinductive microenvironment by developing an ECM using gene-transduced cells. The LIM mineralization protein-1 (LMP-1) gene was transferred to murine pre-osteoblast cells (MC3T3-E1) using lentiviral vectors. Western blotting assay indicated that the MC3T3-E1 cells expressed an increased level of bone morphologic protein-2, -4 and -7 (BMP-2, -4 and -7) after LMP-1 gene transduction. The transduced cells were then seeded into calcined bovine bone scaffolds and cultured for 7, 14, and 21 days to construct ECMs on the scaffolds. The ECM-scaffold composites were then decellularized using the freeze-drying method. Scaffolds without ECM deposition were used as controls. The composites and controls were implanted into critical-sized bone defects created in the distal femurs of New Zealand rabbits. Twelve weeks after the surgery, both microcomputed tomography and histologic results indicated that the 7-day-cell-modified ECM-scaffold composites induced bone regeneration with significantly larger volume, trabecular thickness and connectivity than the controls. However, the 14- and 21-day-cell-modified ECM-scaffold composites triggered sustained inflammation response even at 12 weeks after the surgery and showed less bone ingrowth and integration than their 7-day-cell-modified counterparts. In conclusion, these results highlight the viable gene transfer techniques for manipulating cells in a constructed microenvironment of ECM for bone regeneration. However, the unresolved inflammation relating to the duration of ECM modification needs to be considered.

Demineralized Bone Matrix (DBM) as a Bone Void Filler in Lumbar Interbody Fusion: A Prospective Pilot Study of Simultaneous DBM and Autologous Bone Grafts

Objective

Solid bone fusion is an essential process in spinal stabilization surgery. Recently, as several minimally invasive spinal surgeries have developed, a need of artificial bone substitutes such as demineralized bone matrix (DBM), has arisen. We investigated the in vivo bone growth rate of DBM as a bone void filler compared to a local autologous bone grafts.

Methods

From April 2014 to August 2015, 20 patients with a one or two-level spinal stenosis were included. A posterior lumbar interbody fusion using two cages and pedicle screw fixation was performed for every patient, and each cage was packed with autologous local bone and DBM. Clinical outcomes were assessed using the Numeric Rating Scale (NRS) of leg pain and back pain and the Korean Oswestry Disability Index (K-ODI). Clinical outcome parameters and range of motion (ROM) of the operated level were collected preoperatively and at 3 months, 6 months, and 1 year postoperatively. Computed tomography was performed 1 year after fusion surgery and bone growth of the autologous bone grafts and DBM were analyzed by ImageJ software.

Results

Eighteen patients completed 1 year of follow-up, including 10 men and 8 women, and the mean age was 56.4 (32–71). The operated level ranged from L3/4 to L5/S1. Eleven patients had single level and 7 patients had two-level repairs. The mean back pain NRS improved from 4.61 to 2.78 (p=0.003) and the leg pain NRS improved from 6.89 to 2.39 (p<0.001). The mean K-ODI score also improved from 27.33 to 13.83 (p<0.001). The ROM decreased below 2.0 degrees at the 3-month assessment, and remained less than 2 degrees through the 1 year postoperative assessment. Every local autologous bone graft and DBM packed cage showed bone bridge formation. On the quantitative analysis of bone growth, the autologous bone grafts showed significantly higher bone growth compared to DBM on both coronal and sagittal images (p<0.001 and p=0.028, respectively). Osteoporotic patients showed less bone growth on sagittal images.

Conclusion

Though DBM alone can induce favorable bone bridging in lumbar interbody fusion, it is still inferior to autologous bone grafts. Therefore, DBM is recommended as a bone graft extender rather than bone void filler, particularly in patients with osteoporosis.

Bone Union Rate Following Instrumented Posterolateral Lumbar Fusion: Comparison between Demineralized Bone Matrix versus Hydroxyapatite

Study Design

Retrospective study.

Purpose

To compare the union rate of posterolateral lumbar fusion (PLF) using demineralized bone matrix (DBM) versus hydroxyapatite (HA) as bone graft extender.

Overview of Literature

To our knowledge, there has been no clinical trial to compare the outcomes of DBM versus HA as a graft material for PLF.

Methods

We analyzed prospectively collected data from consecutive 79 patients who underwent instrumented PLF. Patients who received DBM were assigned to group B (n=38), and patients who received HA were assigned into group C (n=41). The primary study outcome was fusion rate assessed with radiographs. The secondary outcomes included pain intensity using a visual analogue scale, functional outcome using Oswestry disability index score, laboratory tests of inflammatory profiles and infection rate.

Results

One year postoperatively, bone fusion was achieved in 73% in group B and 58% in group C without significant difference between the groups (p=0.15). There were no differences between the groups with respect to secondary outcomes.

Conclusions

DBM would provide noninferior outcomes compared to the HA as a fusion material for PLF, and could be a notable alternative.

Treatment of osteonecrosis of the femoral head with free vascularized fibular grafting: Results of 7.6-year follow-up

Objectives

The aim of this study was to determine long term follow up of the patients who had femoral head osteonecrosis and had been treated with free vascularized fibular grafting.

Patients and methods

We retrospectively reviewed 28 hips of 21 patients who had undergone free vascularized fibular grafting for the treatment of osteonecrosis of femoral head. There were 16 male and 5 female patients. The mean age of the patients at the time of surgery was 30.7 years (between 15 and 53 years). The mean follow-up time was 7.6 years (between 5 years and 9.2 years).

Results

During follow-up, one patient died because of leukemia, and one patient was lost. The remaining 26 hips of 19 patients were evaluated. According to the Ficat classification, at the time of surgery, 17 hips were in grade 2 and 9 hips were in grade 3. The post-operative Harris hip scores in grade II disease were excellent in 12 patients, good in 3 patients, and fair in 1 patient. In grade III disease, 1 patient was excellent, 5 patients were good, and 1 patient was fair. There was a significant increase in HHS scores (61 ± 9.7 vs 84 ± 17.8, p < 0.001).

Conclusion

Free vascularized fibular grafting yields extremely good results, particularly in pre-collapse stages of disease in young patients. The operation time does not mark increased if the surgical team is “familiar” with the procedure, and the residual fibular defect of the donor site does not impair the functions of daily living.

Level of Evidence

Level IV, Therapeutic study.

Matched Comparison of Fusion Rates between Hydroxyapatite Demineralized Bone Matrix and Autograft in Lumbar Interbody Fusion

Objective

To compare the fusion rate of a hydroxyapatite demineralized bone matrix (DBM) with post-laminectomy acquired autograft in lumbar interbody fusion surgery and to evaluate the correlation between fusion rate and clinical outcome.

Methods

From January 2013 to April 2014, 98 patients underwent lumbar interbody fusion surgery with hydroxyapatite DBM (HA-DBM group) in our institute. Of those patients, 65 received complete CT scans for 12 months postoperatively in order to evaluate fusion status. For comparison with autograft, we selected another 65 patients who underwent lumbar interbody fusion surgery with post-laminectomy acquired autograft (Autograft group) during the same period. Both fusion material groups were matched in terms of age, sex, body mass index (BMI), and bone mineral density (BMD). To evaluate the clinical outcomes, we analyzed the results of visual analogue scale (VAS), Oswestry Disability Index (ODI), and Short Form Health Survey (SF-36).

Results

We reviewed the CT scans of 149 fusion levels in 130 patients (HA-DBM group, 75 levels/65 patients; Autograft group, 74 levels/65 patients). Age, sex, BMI, and BMD were not significantly different between the groups (p=0.528, p=0.848, p=0.527, and p=0.610, respectively). The HA-DBM group showed 39 of 75 fused levels (52%), and the Autograft group showed 46 of 74 fused levels (62.2%). This difference was not statistically significant (p=0.21). In the HA-DBM group, older age and low BMD were significantly associated with non-fusion (61.24 vs. 66.68, p=0.027; -1.63 vs. -2.29, p=0.015, respectively). VAS and ODI showed significant improvement after surgery when fusion was successfully achieved in both groups (p=0.004, p=0.002, HA-DBM group; p=0.012, p=0.03, Autograft group).

Conclusion

The fusion rates of the hydroxyapatite DBM and Autograft groups were not significantly different. In addition, clinical outcomes were similar between the groups. However, older age and low BMD are risk factors that might induce non-union after surgery with hydroxyapatite DBM.

Comparison of the osteogenic potential of OsteoSelect demineralized bone matrix putty to NovaBone calcium-phosphosilicate synthetic putty in a cranial defect model

The purpose of this study was to compare the osteogenic potential of a synthetic and a demineralized bone matrix (DBM) putty using a cranial defect model in New Zealand white rabbits. Paired, bilateral critical-size defects (10 mm) were prepared in the frontal bones of 12 rabbits and filled with either OsteoSelect DBM Putty or NovaBone calcium-phosphosilicate putty. At days 43 and 91, 6 rabbits were killed and examined via semiquantitative histology and quantitative histomorphometry. Defects filled with the DBM putty were histologically associated with less inflammation and fibrous tissue in the defect and more new bone than the synthetic counterpart at both time points. Histomorphometric analysis revealed that the defects filled with DBM putty were associated with significantly more bone formation at day 43 (70.7% vs 40.7%, P = 0.043) and at day 91 (70.4% vs 39.9%, P = 0.0044). The amount of residual implant was similar for both test groups at each time point.

Remineralization of demineralized bone matrix in critical size cranial defects in rats: A 6-month follow-up study

The key drawback of using demineralized bone matrix (DBM) is its low initial mechanical stability due to the severe depletion of mineral content. In the present study, we investigated the long-term regeneration of DBM in a critical size bone defect model and investigated the remineralization after 6 months. Bone defects were created in the cranium of male Wistar rats which were filled with DBM or left empty as negative control. In vivo bone formation was monitored with computed tomography after 11, 19, and 26 weeks postoperatively. After 6 months, parietal bones were subjected to micro-CT. Mineral content was determined with spectrophotometric analysis. After 11 weeks the DBM-filled bone defects were completely closed, while empty defects were still open. Density of the DBM-treated group increased significantly while the controls remained unchanged. Quantitative analysis by micro-CT confirmed the in vivo results, bone volume/tissue volume was significantly lower in the controls than in the DBM group. The demineralization procedure depleted the key minerals of the bone to a very low level. Six months after implantation Ca, P, Na, Mg, Zn, and Cr contents were completely restored to the normal level, while K, Sr, and Mn were only partially restored. The remineralization process of DBM is largely complete by the 6th month after implantation in terms of bone density, structure, and key mineral levels. Although DBM does not provide sufficient sources for any of these minerals, it induces a faster and more complete regeneration process. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1336-1342, 2016.

Is DBM beneficial for the enhancement of bony consolidation in distraction osteogenesis? A randomized controlled trial

The aim of the present study was to compare the radiographic and clinical outcomes of DBM injection and conventional treatment during tibial lengthening over an intramedullary nail in adult patients with short stature. Twenty-nine patients were randomized to receive DBM injection (n = 14) or conventional treatment without any injection (n = 15) and evaluated. The outcome was measured on the basis of the pixel value ratio (PVR) in the digital radiographs during the consolidation period; healing index; clinical assessment; and the rate of complications. In the DBM group, the mean PVR of 1 (mineral density of the callus is comparable to the adjacent bone) was reached by 40 weeks in anterior and medial cortices which was significantly different than that in the control group (P = 0.03 for anterior cortex; P = 0.04 for medial cortex). The average healing index in the DBM group was 39.8 ± 5.3 days/cm compared to 44.3 ± 5.8 days/cm in the control group (P = 0.05). There were no significant differences in clinical outcomes (P = 0.23) and functional status (P = 0.47) including complications (P = 0.72) between two groups. In this randomized clinical trial, injection of DBM at the time of initial operation enhanced consolidation of regenerate callus without interfering with clinical outcomes compared to that with conventional treatment.

A Prospective Randomized Clinical Trial Comparing Bone Union Rate Following Anterior Cervical Discectomy and Fusion Using a Polyetheretherketone Cage: Hydroxyapatite/B-Tricalcium Phosphate Mixture versus Hydroxyapatite/Demineralized Bone Matrix Mixture

STUDY DESIGN

Prospective randomized noninferiority trial.

PURPOSE

To evaluate whether the union rate of anterior cervical discectomy and fusion (ACDF) using a polyetheretherketone (PEEK) cage filled with a mixture of hydroxyapatite (HA) and demineralized bone matrix (DBM) is inferior to that of a mixture of β-tricalcium phosphate (β-TCP) and HA.

OVERVIEW OF LITERATURE

There have been no clinical trials investigating the outcomes of a mixture of HA and DBM in a PEEK cage in ACDF.

METHODS

Eighty-five eligible patients were randomly assigned to group B (n=43), in which a PEEK cage with a mixture of HA and DBM was used, or group C (n=42), in which a PEEK cage with a mixture of HA and β-TCP was used. The primary study endpoint was the fusion rate, which was assessed with dynamic radiographs and computed tomography (CT) scans. Secondary endpoints included pain intensity using a visual analogue scale, functional outcome using a neck disability index score, laboratory tests of inflammatory profiles, and the infection rate.

RESULTS

Seventy-seven patients (38 in group B and 39 in group C) were included in the final analysis. One year postoperatively, bone fusion was achieved in 87% of group B patients and 87% of group C patients on dynamic radiographs, and 87% of group B patients and 72% of group C patients on CT scans (p=1.00 and 0.16, respectively). There were also no between-groups differences with respect to the secondary endpoints.

CONCLUSIONS

A HA/DBM mixture inside a PEEK cage can provide noninferior outcomes compared to a HA/TCP mixture in ACDF.

A prospective randomized comparison of PEEK cage containing calcium sulphate or demineralized bone matrix with autograft in anterior cervical interbody fusion

PURPOSE

A variety of bone substitutes have been successfully used to fill PEEK cages in cervical interbody fusion in order to avoid the complications related to bone harvesting from the donor site. However, no controlled study has previously been conducted to compare the effectiveness of PEEK interbody cages containing calcium sulphate/ demineralized bone matrix (CS/DBM) with autogenous cancellous bone for the treatment of cervical spondylosis. The objective of this prospective, randomized clinical study was to evaluate the effectiveness of implanting PEEK cages containing CS/DBM for the treatment of cervical radiculopathy and/or myelopathy.

METHODS

Sixty-eight patients with cervical radiculopathy and/or myelopathy were randomly assigned to receive one- or two-level discectomy and fusion with PEEK interbody cages containing CS/DBM or autogenous iliac cancellous bone (AIB). The patients were followed up for two years postoperatively. The radiological and clinical outcomes were assessed during a two-year follow-up.

RESULTS

The mean blood loss was 75 ± 18.5 ml in the CS/DBM group and 100 ± 19.6 ml (P < 0.01) in the AIB group. The fusion rate was 94.3 % in the CS/DBM group and 100 % in the AIB group at 12-month follow-up. The fusion rate was 100 % at final follow-up in both groups. No significant difference (P > 0.05) was found regarding improvement of JOA score and segmental lordosis as well as neck and arm pain at all time intervals between the two groups. The total complication rate was significantly higher (P < 0.05) in the AIB group than in the CS/DBM group, but there was no significant difference between the two groups (P > 0.05) when comparing the complications in the neck.

CONCLUSIONS

In conclusion, the PEEK interbody fusion cage containing CS/DBM or AIB following one- or two-level discectomy had a similar outcome for cervical spondylotic radiculopathy and/or myelopathy. The rate of fusion and the recovery rate of JOA score between the two groups were the same. The filling of CS/DBM in the PEEK cage instead of AIB has the advantage of less operative blood loss and fewer complications at the donor site.

Evaluation of a new formulation of demineralized bone matrix putty in a rabbit posterolateral spinal fusion model

BACKGROUND CONTEXT

Alternatives to autologous bone graft (ABG) with osteoconductive, osteoinductive, and osteogenic potential continue to prove elusive. Demineralized bone matrix (DBM) however, with its osteoconductive and osteoinductive potential remains a viable option to ABG in posterolateral spine fusion.

PURPOSE

To compare the efficacy of a new formulation of DBM putty with that of ABG in a rabbit posterolateral spinal fusion model.

STUDY DESIGN

Efficacy of a new formulation of DBM was studied in an experimental animal posterolateral spinal fusion model.

METHODS

Twenty-four male New Zealand White rabbits underwent bilateral posterolateral spine arthrodesis of the L5-L6 intertransverse processes, using either ABG (control group, n=12) or DBM (DBM made from rabbit bone) putty (test group, n=12). The animals were killed 12 weeks after surgery and the lumbar spines were excised. Fusion success was evaluated by manual palpation, high resolution X-rays, microcomputed tomography imaging, biomechanical four-point bending tests, and histology.

RESULTS

Two animals were lost because of anesthetic related issues. Manual palpation to assess fusion success in the explanted lumbar spines showed no statistical significant difference in successful fusion in 81.8% (9/11) of DBM group and 72.7% (8/11) of ABG group (p=.99). Reliability of these assessments was measured between three independent observers and found near perfect agreement (intraclass correlation cofficient: 0.92 and 0.94, respectively). Fusion using high resolution X-rays was solid in 10 of the DBM group and 9 of the ABG group (p=.59). Biomechanical testing showed no significant difference in stiffness between the control and test groups on flexion, extension, and left lateral and right lateral bends, with p values accounting for .79, .42, .75, and .52, respectively. The bone volume/total volume was greater than 85% in the DBM treated fusion masses. Histologic evaluation revealed endochondral ossification in both groups, but the fusion masses were more mature in the DBM group.

CONCLUSIONS

The DBM putty achieved comparable fusion rates to ABG in the rabbit posterolateral spinal fusion model.

Demineralized bone matrix, as a graft enhancer of auto-local bone in posterior lumbar interbody fusion

Study Design

A case controlled study with prospective data collection.

Purpose

To evaluate the early influence and the final consequence of demineralized bone matrix (DBM) on auto-local bone as a graft enhancer in posterior lumbar interbody fusion (PLIF).

Overview of Literature

DBM is known as an osteoinductive material; however, it has not been clearly recognized to enhance auto-local bone with a small amount.

Methods

Patients who had a PLIF were allocated into two groups. Group I (70 cases) used auto-local bone chips and group II (44 cases) used DBM as an additive to auto-local bone, 1 mL per a segment. Group selection was alternated. Early assessment was performed by computed tomography at 6 months and final assessment was done by simple radiography after 24 months at least. The degree of bone formation was assessed by 4 grade scale.

Results

The subjects of both groups were homogenous and had similar Oswestry Disability Index at final assessment. The ratio of auto-local bone chips and DBM was 6:1. The degree of bone formation at 6 months after surgery was superior in group II. However, there was no significant difference between the two groups at the final assessment.

Conclusions

DBM was not recognized to enhance auto-local bone with small amount.

Decellularized tissue and cell-derived extracellular matrices as scaffolds for orthopaedic tissue engineering

The reconstruction of musculoskeletal defects is a constant challenge for orthopaedic surgeons. Musculoskeletal injuries such as fractures, chondral lesions, infections and tumor debulking can often lead to large tissue voids requiring reconstruction with tissue grafts. Autografts are currently the gold standard in orthopaedic tissue reconstruction; however, there is a limit to the amount of tissue that can be harvested before compromising the donor site. Tissue engineering strategies using allogeneic or xenogeneic decellularized bone, cartilage, skeletal muscle, tendon and ligament have emerged as promising potential alternative treatment. The extracellular matrix provides a natural scaffold for cell attachment, proliferation and differentiation. Decellularization of in vitro cell-derived matrices can also enable the generation of autologous constructs from tissue specific cells or progenitor cells. Although decellularized bone tissue is widely used clinically in orthopaedic applications, the exciting potential of decellularized cartilage, skeletal muscle, tendon and ligament cell-derived matrices has only recently begun to be explored for ultimate translation to the orthopaedic clinic.

Two-stage distraction lengthening of the forearm

Single-stage lengthening of the forearm using callus distraction is well described; however, forearm lengthening using a 2-stage technique of distraction followed by bone grafting has received less attention. A 2-staged technique can be a better alternative in cases where the surgeon desires extensive lengthening. A retrospective review was undertaken of eleven 2-stage forearm lengthening procedures performed by 1 surgeon over a 15-year period. Indications were radial longitudinal deficiency (8 patients), neonatal ischemic contractures (2 patients), and septic growth arrest (1 patient). Average follow-up was 2.8 years. Distraction was performed on patients an average of 82 mm over an average duration of 24 weeks. Average time to union from the time of distractor removal and grafting was 87 days. Average healing index was 32.1 d/cm. Distraction problems were common and related to the length of time that the distractor was in place; they included pain, pin-related infections, and multiple mechanical device difficulties. Three patients had nonunion, and another had delayed union; however, additional procedures resulted in ultimate bony union in all patients. Demineralized bone matrix and autologous corticocancellous bone grafts yielded predictable healing and good functional results in short-distance distractions. For longer distractions, free vascularized fibula transfer produced the best outcomes. Intercalary cortical allografts did not heal well. Patients with neonatal Volkmann contractures had the most difficulty with distraction and healing, ultimately obtaining little to no lengthening and poor functional outcomes.

Histological remodelling of demineralised bone matrix allograft in posterolateral fusion of the spine--an ex vivo study

Background

Demineralised bone matrix (DBM) has shown to be effective in enhancing posterior fusion of the spine. Several animal studies and clinical investigations in humans showed its successful remodelling. The use of allogenic matrix may decrease the need of autologous bone graft and therefore helps prevent corresponding donor site morbidity. Since DBM products are very expensive, the question arises, whether it is completely remodelled into new bone, and therefore truly is comparable to autologous cancellous bone graft. To our knowledge there is no report of a consecutive series of patients where ex vivo histological analysis after postero-lateral fusion of the spine was performed.

Methods

Osseous biopsies of nine consecutive patients who underwent postero-lateral fusion of the spine for trauma were obtained at the time of elective removal of the hardware. Histological samples were then analyzed on ground and thin sections stained with toluidine blue and von Kossa stainings.

Results

Time span between index operation and removal of the metal ranged between 6 and 18 month. Histological analysis showed good incorporation and overall remodelling of DBM into new bone in all patients. No foreign body reaction was visible and new bone formation progressed time dependently with DBM in situ. Four out of nine patients showed more than 50% new bone formation after one year.

Conclusion

DBM shows good overall remodelling properties in histological analysis and therefore seems to be an effective adjunct in postero-lateral fusion of the spine. Furthermore, DBM substitution increases over time.

Tissue engineering strategies in spinal arthrodesis: the clinical imperative and challenges to clinical translation

Skeletal disorders requiring the regeneration or de novo production of bone present considerable reconstructive challenges and are one of the main driving forces for the development of skeletal tissue engineering strategies. The skeletal or mesenchymal stem cell is a fundamental requirement for osteogenesis and plays a pivotal role in the design and application of these strategies. Research activity has focused on incorporating the biological role of the mesenchymal stem cell with the developing fields of material science and gene therapy in order to create a construct that is not only capable of inducing host osteoblasts to produce bone, but is also osteogenic in its own right. This review explores the clinical need for reparative approaches in spinal arthrodesis, identifying recent tissue engineering strategies employed to promote spinal fusion, and considers the ongoing challenges to successful clinical translation.

Short Term Culture of Human Mesenchymal Stem Cells with Commercial Osteoconductive Carriers Provides Unique Insights into Biocompatibility

For spinal fusions and the treatment of non-union fractures, biological substrates, scaffolds, or carriers often are applied as a graft to support regeneration of bone. The selection of an appropriate material critically influences cellular function and, ultimately, patient outcomes. Human bone marrow mesenchymal stem cells (BMSCs) are regarded as a critical component of bone healing. However, the interactions of BMSCs and commercial bone matrices are poorly reported. BMSCs were cultured with several commercially available bone substrates (allograft, demineralized bone matrix (DBM), collagen, and various forms of calcium phosphates) for 48 h to understand their response to graft materials during surgical preparation and the first days following implantation (cell retention, gene expression, pH). At 30 and 60 min, bone chips and inorganic substrates supported significantly more cell retention than other materials, while collagen-containing materials became soluble and lost their structure. At 48 h, cells bound to β-tricalcium phosphate-hydroxyapatite (βTCP-HA) and porous hydroxyapatite (HA) granules exhibited osteogenic gene expression statistically similar to bone chips. Through 24 h, the DBM strip and βTCP-collagen became mildly acidic (pH 7.1–7.3), while the DBM poloxamer-putties demonstrated acidity (pH < 5) and the bioglass-containing carrier became basic (pH > 10). The dissolution of DBM and collagen led to a loss of cells, while excessive pH changes potentially diminish cell viability and metabolism. Extracts from DBM-poloxamers induced osteogenic gene expression at 48 h. This study highlights the role that biochemical and structural properties of biomaterials play in cellular function, potentially enhancing or diminishing the efficacy of the overall therapy.

Substitutes of structural and non-structural autologous bone grafts in hindfoot arthrodeses and osteotomies: a systematic review

Background

Structural and non-structural substitutes of autologous bone grafts are frequently used in hindfoot arthrodeses and osteotomies. However, their efficacy is unclear.

The primary goal of this systematic review was to compare autologous bone grafts with structural and non-structural substitutes regarding the odds of union in hindfoot arthrodeses and osteotomies.

Methods

The Medline and EMBASE and Cochrane databases were searched for relevant randomized and non-randomized prospective studies as well as retrospective comparative chart reviews.

Results

10 studies which comprised 928 hindfoot arthrodeses and osteotomies met the inclusion criteria for this systematic review. The quality of the retrieved studies was low due to small samples sizes and confounding variables. The pooled random effect odds for union were 12.8 (95% CI 12.7 to 12.9) for structural allografts, 5.7 (95% CI 5.5 to 6.0) for cortical autologous grafts, 7.3 (95% CI 6.0 to 8.6) for cancellous allografts and 6.0 (95% CI 5.7 to 6.4) for cancellous autologous grafts. In individual studies, the odds of union in hindfoot arthrodeses achieved with cancellous autologous grafts was similar to those achieved with demineralised bone matrix or platelet derived growth factor augmented ceramic granules.

Conclusion

Our results suggest an equivalent incorporation of structural allografts as compared to autologous grafts in hindfoot arthrodeses and osteotomies. There is a need for prospective randomized trials to further clarify the role of substitutes of autologous bone grafts in hindfoot surgery.

Improving the clinical evidence of bone graft substitute technology in lumbar spine surgery

Bone graft substitutes have been used routinely for spine fusion for decades, yet clinical evidence establishing comparative data remains sparse. With recent scrutiny paid to the outcomes, complications, and costs associated with osteobiologics, a need to improve available data guiding efficacious use exists. We review the currently available clinical literature, studying the outcomes of various biologics in posterolateral lumbar spine fusion, and establish the need for a multicenter, independent osteobiologics registry.

EFFECT OF PURIFIED ALGINATE MICROCAPSULES ON THE REGENERATION OF CHONDROCYTES

Adult articular cartilage tissue has poor capability of self-repair. Therefore, a variety of tissue engineering approaches are motivated by the clinical need for articular repair. Alginate has been used as a biomaterial for cartilage regeneration. The alginate is a natural polymer that is extracted from seaweeds and purification. However, the main drawback is the immune rejection in vivo. To overcome this problem, we have developed the biocompability of alginate using modified Korbutt method. After alginate was purified, purified alginate microcapsules were used in cartilage regeneration. Chondrocytes were seeded in purified and nonpurified alginate microcapsules, and then cell viability, proliferation and phenotype were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. Reverse transcriptase-polymerase chain reaction (RT-PCR) was conducted to confirm mRNA expression on collagen type I and collagen type II for chondrocytes phenotype. Hematoxylin and eosin (H&E) and Safranin-O histological staining showed tissue growth at the interface during the first 10 days. In this study, chondrocytes in purified alginate microcapsules had higher cell viability, proliferation and more phenotype expression than those in nonpurified alginate microcapsules. The results suggest that the purified alginate microcapsule is useful for cartilage regeneration.

Demineralized bone matrix in bone repair: history and use

Demineralized bone matrix (DBM) is an osteoconductive and osteoinductive commercial biomaterial and approved medical device used in bone defects with a long track record of clinical use in diverse forms. True to its name and as an acid-extracted organic matrix from human bone sources, DBM retains much of the proteinaceous components native to bone, with small amounts of calcium-based solids, inorganic phosphates and some trace cell debris. Many of DBM's proteinaceous components (e.g., growth factors) are known to be potent osteogenic agents. Commercially sourced as putty, paste, sheets and flexible pieces, DBM provides a degradable matrix facilitating endogenous release of these compounds to the bone wound sites where it is surgically placed to fill bone defects, inducing new bone formation and accelerating healing. Given DBM's long clinical track record and commercial accessibility in standard forms and sources, opportunities to further develop and validate DBM as a versatile bone biomaterial in orthopedic repair and regenerative medicine contexts are attractive.

Nanostructured biomaterials for tissue engineered bone tissue reconstruction

Bone tissue engineering strategies are emerging as attractive alternatives to autografts and allografts in bone tissue reconstruction, in particular thanks to their association with nanotechnologies. Nanostructured biomaterials, indeed, mimic the extracellular matrix (ECM) of the natural bone, creating an artificial microenvironment that promotes cell adhesion, proliferation and differentiation. At the same time, the possibility to easily isolate mesenchymal stem cells (MSCs) from different adult tissues together with their multi-lineage differentiation potential makes them an interesting tool in the field of bone tissue engineering. This review gives an overview of the most promising nanostructured biomaterials, used alone or in combination with MSCs, which could in future be employed as bone substitutes. Recent works indicate that composite scaffolds made of ceramics/metals or ceramics/polymers are undoubtedly more effective than the single counterparts in terms of osteoconductivity, osteogenicity and osteoinductivity. A better understanding of the interactions between MSCs and nanostructured biomaterials will surely contribute to the progress of bone tissue engineering.

Feasibility of demineralized bone matrix for craniomaxillofacial contour restoration

Demineralized bone matrix (DBM) could be a good alternative for craniomaxillofacial contour restoration, especially in perialar, malar, temporal, and frontal regions. In this study, the histologic behavior of DBM was investigated in different tissue planes to determine its proper application plane for restoration of craniomaxillofacial contour deformities and defects.Forty Wistar rats were divided into 6 groups: (1) 0.3 mL of 0.9% saline was injected into the subperiosteal plane of the cranium, (2) 0.3 mL of DBM was implanted into the subperiosteal plane of the cranium, (3) 0.3 mL of 0.9% saline was injected into the subdermal plane on the left inguinal region, (4) 0.3 mL of DBM was implanted into the subdermal plane on the right inguinal region, (5) 0.3 mL of 0.9% saline was injected between the left external and internal oblique muscles, and (6) 0.3 mL of DBM was implanted between the right external and internal oblique muscles. At the 8th week half of the rats and at 16th week the remaining rats were killed in each group, and tissue samples were harvested. Histological and immunohistochemical evaluation revealed new bone tissue and bone marrow formation in all planes that DBM was given.Demineralized bone matrix can provide satisfactory results in craniomaxillofacial contour deformities including forehead, temporal, and malar augmentations, as well as mental and perialar augmentations and saddle nose corrections, with supraperiosteal or deep subcutaneous applications. However, superficial applications must be avoided because of the possibility of palpation, because it induces hard bone tissue formation in all tissue planes.

Open reduction and internal fixation of clavicular nonunions with allograft bone substitute

Background:

Biologic augmentation with allograft has shown equivalent healing rates to autograft in several nonunion models. No literature exists clearly demonstrating this in the clavicle. The purpose of this study was to evaluate the healing and complication rates of clavicle nonunions treated solely with open reduction and internal fixation (ORIF) and allograft.

Materials and Methods:

Nineteen clavicle nonunions treated with ORIF and allograft were evaluated retrospectively to assess healing rates and complications based on clinical symptoms and radiographic findings.

Results:

For the 19 patients included and treated with ORIF and allograft, clinical follow-up averaged 15 months. Seven patients were smokers. Although complete radiographic healing was achieved in only 68% of patients, clinical success occurred in 16 (84%) patients who demonstrated full range of motion and strength without pain. The three patients who did not demonstrate full radiographic healing were completely pain free. Five patients experienced complications (26%). Two underwent hardware removal due to persistent irritation after union. Three had a persistent painful nonunion. Each of these three patients was a smoker (P=0.08). Two proceeded to union after revision fixation. The other had hardware failure, which was removed, with a persistent nonunion and did not wish any further treatment.

Conclusion:

ORIF with allograft bone substitute is an acceptable treatment alternative to iliac crest bone graft for clavicle nonunions. However, we did not demonstrate equivalent healing rates to published results utilizing autograft. Smokers were identified to have a trend toward higher failure rates with ORIF augmented with allograft and therefore these patients may be better served by augmenting fixation with autograft.

Level of Evidence:

IV; retrospective comparative study.

Biomimetic Nanostructured Materials — Potential Regulators for Osteogenesis?

Nanostructured materials are gaining new impetus owing to the advancements in material fabrication techniques and their unique properties (their nanosize, high surface area-to-volume ratio, and high porosity). Such nanostructured materials mimic the subtleties of extracellular matrix (ECM) proteins, creating artificial microenvironments which resemble the native niches in the body. On the other hand, the isolation of mesenchymal stem cells (MSCs) from various tissue sources has resulted in the interest to study the multiple differentiation lineages for various therapeutic treatments. In this review, our focus is tailored towards the potential of biomimetic nanostructured materials as osteoinductive scaffolds for bone regeneration to differentiate MSCs towards osteoblastic cell types without the presence of soluble factors. In addition to mimicking the nanostructure of native bone, the supplement of collagen and hydroxyapatite which mimic the main components of the ECM also brings significant advantages to these materials. Key words: Biomaterials, Biomimetic, Bone, Hydroxyapatites, Nanomaterials, Stem cells, Tissue engineering

Mesenchymal stem cell responses to bone-mimetic electrospun matrices composed of polycaprolactone, collagen I and nanoparticulate hydroxyapatite

The performance of biomaterials designed for bone repair depends, in part, on the ability of the material to support the adhesion and survival of mesenchymal stem cells (MSCs). In this study, a nanofibrous bone-mimicking scaffold was electrospun from a mixture of polycaprolactone (PCL), collagen I, and hydroxyapatite (HA) nanoparticles with a dry weight ratio of 50/30/20 respectively (PCL/col/HA). The cytocompatibility of this tri-component scaffold was compared with three other scaffold formulations: 100% PCL (PCL), 100% collagen I (col), and a bi-component scaffold containing 80% PCL/20% HA (PCL/HA). Scanning electron microscopy, fluorescent live cell imaging, and MTS assays showed that MSCs adhered to the PCL, PCL/HA and PCL/col/HA scaffolds, however more rapid cell spreading and significantly greater cell proliferation was observed for MSCs on the tri-component bone-mimetic scaffolds. In contrast, the col scaffolds did not support cell spreading or survival, possibly due to the low tensile modulus of this material. PCL/col/HA scaffolds adsorbed a substantially greater quantity of the adhesive proteins, fibronectin and vitronectin, than PCL or PCL/HA following in vitro exposure to serum, or placement into rat tibiae, which may have contributed to the favorable cell responses to the tri-component substrates. In addition, cells seeded onto PCL/col/HA scaffolds showed markedly increased levels of phosphorylated FAK, a marker of integrin activation and a signaling molecule known to be important for directing cell survival and osteoblastic differentiation. Collectively these results suggest that electrospun bone-mimetic matrices serve as promising degradable substrates for bone regenerative applications.

Artrodese na coluna cervical utilizando SICAP como substituto de enxerto ósseo

OBJETIVO: Substitutos de enxerto ósseo autólogo foram desenvolvidos para evitar as complicações da retirada de enxerto ósseo autólogo. SiCaP (Actifuse, ApaTech EUA, Reino Unido) é um enxerto ósseo composto de cálcio-fosfato com um substituição de silicato na estrutura química, com uma estrutura tridimensional que parece osso natural. MÉTODOS: 19 pacientes foram submetidos à fusão óssea cervical e analisados retrospectivamente. A avaliação radiográfica e avaliação clínica foram realizadas utilizando o questionário Neck Disability Index e a escala análoga da dor (VAS) pré- e pós-operação. RESULTADOS: O período médio de acompanhamento pós-operatório foi de 14 meses ± 5 meses (7-30 meses). 11 pacientes foram submetidos à fusão via anterior; 5 pacientes via posterior e 3 pacientes via anterior e posterior. A revisão radiográfica mostrou 19/19 (100%) de fusão óssea, nenhum caso apresentou subsidência, quebra ou soltura de material de implante ou movimento nos níveis fusionados. Nenhum exemplo de ossificação heterotópica ou de crescimento ósseo intracanal foi observado. Clinicamente, os escores médios do Neck Disability decresceram 13,3 pontos (media pré-op. de 34,5, pós-op. de 21,2, melhora de 39%), a média da VAS para dor cervical decresceu 2 pontos (2,7 pré-op para 0,7 pós-op.; melhora de 74,1%). Não foram observadas complicações como infecção, osteólise ou edema excessivo das partes moles. CONCLUSÃO: Os resultados preliminares obtidos nesta série foram encorajadores com o uso do SICaP como enxerto ósseo, com sólida fusão óssea obtida em todos os casos e sem formação de ossificação heterotópica ou crescimento de osso intracanal. SIcaP demonstra ser um substituto confiável para o enxerto ósseo autólogo na coluna cervical.