In this study, we aimed to investigate tibiofemoral and allograft loading parameters after OCA transplantation using tibial plateau shell grafts to characterize the clinically relevant biomechanics that may influence joint kinematics and OCA osseointegration after transplantation. The study was designed to test the hypothesis that there are significant changes in joint loading after tibial plateau OCA transplantation that may require unique post-operative rehabilitation regimens in patients to restore balance in the knee joint. Fresh-frozen cadaveric knees (n=6) were thawed and mounted onto a 6 DOF KUKA robot. Specimens were size matched to +2 mm for the medial-to-lateral width of the medial tibial hemiplateaus. Three specimens served as allograft recipient knees and three served as donor knees. Recipient knees were first tested in their native state and then tested with size-matched medial tibial hemiplateau shell grafts (n=3) prepared from the donor knees using custom-cut tab-in-slot and subchondral drilling techniques. Tekscan sensors were placed in the joint spaces to evaluate the loading conditions under 90N biaxial loading at full extension of the knee before and after graft placement. The I-Scan system used in conjunction analyzed the total force, pressure distribution, peak pressure, and center of force within the joint space. Data demonstrated significant difference (p<0.05) in joint space loading after graft implantation compared to controls in both lateral and medial tibial plateaus. The I-Scan pressure mapping system displayed changes in femoral condylar contact points as well. The results demonstrated that joint space loading was significantly different (p<0.05) between all preoperative and postoperative cadaveric specimens. Despite the best efforts to size match grafts, slight differences in the host's joint geometry resulted in shifts of contact areas between the tibial plateau and femoral condyle therefore causing either an increase or decrease in pressure measured by the sensor. This concludes that accuracy in graft size matching is extremely important to restoring close to normal loading across the joint and this can be further ensured through postoperative care customized to the patient after OCA surgery

Screw fixation is an established method for anterior cruciate ligament (ACL) reconstruction, although with a high rate of implant-related complications. An allograft system for implant fixation in ACL reconstruction, the Shark Screw ACL (surgebright GmbH) could overcome some of the shortcomings of bioabsorbable screws, such as foreign body reaction, need for implant removal and imaging artefacts. However, it needs to provide sufficient mechanical stability. Therefore, the aim of this study was to investigate the biomechanical stability, especially graft slippage, of the novel allograft system versus a conventional bioabsorbable interference screw (BioComposite Interference Screw; Arthrex Inc.) for tibial implant fixation in ACL reconstruction. Twenty-four paired human proximal tibiae (3 female, 9 male, 72.7 ± 5.6 years) underwent ACL reconstruction. The quadrupled semitendinosus and gracilis tendon graft were fixed in one specimen of each pair using the allograft fixation system Shak Screw ACL and the contralateral one using an interference screw. All specimens were cyclically loaded at 1 Hz with peak load levels monotonically increased from 50 N at a rate of 0.1 N/cycle until catastrophic failure. Relative movements of the graft versus the tibia were captured with a stereographic optical motion tracking system (Aramis SRX; GOM GmbH). The two fixation methods did not demonstrate any statistical difference in ultimate load at graft slippage (p = 0.24) or estimated survival at slippage (p = 0.06). Both, the ultimate load and estimated survival until failure were higher in the interference screw (p = 0.04, and p = 0.018, respectively). Graft displacement at ultimate load reached values of up to 7.2 mm (interference screw) and 11.3 mm (Shark Screw ACL). The allograft screw for implant fixation in ACL reconstruction showed similar behavior in terms of graft slippage compared to the conventional metal interference screw but underperformed in terms of ultimate load. However, the ultimate load may not be considered a direct indicator of clinical failure

Many factors have been reported to affect the functional survival of OCA transplants, including chondrocyte viability at time of transplantation, rate and extent of allograft bone integration, transplantation techniques, and postoperative rehabilitation protocols and adherence. The objective of this study was to determine the optimal subchondral bone drilling technique by evaluating the effects of hole diameter on the material properties of OCAs while also considering total surface area for potential biologic benefits for cell and vascular ingrowth. Using allograft tissues that would be otherwise discarded in combination with deidentified diagnostic imaging (MRI and CT), a model of a large shell osteochondral allograft was recreated using LS-PrePost and FEBio based on clinically relevant elastic material properties for cortical bone, trabecular bone, cartilage, and hole ingrowth tissue. The 0.8 mesh size model consisted of 4 mm trabecular bone, 4 mm cortical bone, and 3 mm cartilage sections that summed to a cross-sectional area of 1600 mm2 (40 mm x 40 mm). Holes were modeled to be 4mm deep in relation to clinical practice where holes are drilled from the deep margin of subchondral trabecular bone to the cortical subchondral bone plate. To test the biomechanic variations between drill hole sizes, models with hole sizes pertinent to standard-of-care commercially available orthopaedic drill sizes of 1.1mm, 2.4 mm, or 4.0 mm holes were loaded across the top surface over a one second duration and evaluated for effective stress, effective strain, 1st principal strain, and 3rd principal strain in compressive conditions. Results measured effective stress and strain and 1st and 3rd principal strain increased with hole depth. The results of the present FEA modeling study indicate that the larger 4.0 mm diameter holes were associated with greater stresses and strains within OCA shell graft, which may render the allograft at higher risk for mechanical failure. Based on these initial results, the smaller diameter 2.4 mm and 1.1 mm holes will be further investigated to determine optimal number, configuration, and depth of subchondral drilling for OCA preparation for transplantation

The purpose of this study is to enhance massive bone allografts osseointegration used to reconstruct large bone defects. These allografts show >50% complication rate requiring surgical revision in 20% cases. A new protocol for total bone decellularisation exploiting the vasculature can offer a reduction of postoperative complication by annihilating immune response and improving cellular colonization/ osseointegration. The nutrient artery of 18 porcine bones - humerus/femur/radius/ulna - was cannulated. The decellularization process involved immersion and sequential perfusion with specific solvents over a course of one week. Perfusion was realized by a peristaltic pump (mean flow rate: 6ml/min). The benefit of arterial perfusion was compared to a control group kept in immersion baths without perfusion. Bone samples were processed for histology (HE, Masson's trichrome and DAPI for cell detection), immunohistochemistry (IHC : Collagen IV/elastin for intraosseous vascular system evaluation, Swine Leukocyte Antigen – SLA for immunogenicity in addition to cellular clearance) and DNA quantification. Sterility and solvent residues in the graft were also evaluated with thioglycolate test and pH test respectively. Compared to native bones, no cells could be detected and residual DNA was <50ng/mg dry weight. Intramedullary spaces were completely cleaned. IHC showed the preservation of intracortical vasculature with channels bounded by Collagen IV and elastin within Haversian systems. IHC also showed a significant decrease in SLA signaling. All grafts were sterile at the last decellularization step and showed no solvent residue. The control group kept in immersion baths, paired with 6 perfused radii/ulnae, showed that the perfusion is mandatory to ensure complete decellularisation. Our results prove the effectiveness of a new concept of total bone decellularisation by perfusion. These promising results could lead to a new technique of Vascularized Composite Allograft transposable to pre-clinical and clinical models

Bone infections due to fractures or implants are a big medical problem. In experimental medicine, many experimental models have been created on different animal species to simulate the disease condition and to do experience treatments. The aim of this paper was to present an antibacterial efficacy of using a bone allograft developed according to the Marburg system of bone bank on a model of chronic osteomyelitis induced in rabbits. In research was used 54 rabbits. Osteomyelitis was induced in rabbits by a human strain of St. aureus ATCC 43300, in the rabbit femur. There have been created 3 groups of animals. In 1. st. group used antibiotic impregnated biodegradable material “PerOssal”. In 2. nd. group used antibiotic impregnated whole bone allograft. In 3. rd. group used antibiotic impregnated perforated bone allograft. Evaluation of installation and evolution of the disease was done by microbiological. A separate study of microbiological data is presented here. This study showed, in the 1. st. and 3. rd. groups there is a persistent decrease in CFU by 14 knocks to 120.4 in the 1. st. group and to 3.5 in the 3. rd. group, and in the 2. nd. group, on the contrary, there is an increase in CFU to 237.33. This shows the lack of effectiveness of using a whole bone allograft. The results showed, after 7 days there was no statistically significant difference between the groups. After 14 days the perforated bone allograft impregnated with antibiotic was better than the biodegradable material “PerOssal”

Introduction. Cancellous and cortical bone used as a delivery vehicle for antibiotics. Recent studies with cancellous bone as an antibiotic carrier in vitro and in vivo showed high initial peak concentrations of antibiotics in the surrounding medium. However, high concentrations of antibiotics can substantially reduce osteoblast replication and even cause cell death. Objectives. To determine whether impregnation with gentamycine impair the incorporation of bone allografts, as compared to allografts without antibiotic. Materials and method. Seventy two healthy rabbits (24 rabbits in each group) were used for this study. Bone defects (3-mm diameter, 10-mm depth) were created in the femur. Human femoral head prepared according to the Marburg bone bank system was used as bone allograft. In the experimental groups, in 1 group - the defects were filled with bone allografts, in 2 group – Perforated Gentamycin-impregnated bone allografts. The control group did not receive any filling. The animals were killed after 14, 30 and 60 days. Evaluations consisted of X-ray plain radiography, histology at 14-, 30- and 60-days post-surgery. Results. Active osteoblast activity and active formation of new bones were detected around the defect area in all groups, but the amount of new bone formation was greater in the experimental groups than the control group. We found no statistically significant differences in the rate of bone formation between 1 and 2 groups at 14, 30 and 60 days in any of the parameters studied. X-ray results showed no significant difference in bony callus formation around allografts in 1 and 2 groups. In contrast, no significant callus formation was observed in the control group. Conclusion. The use of gentamycin-impregnated bone allografts may be of value in procedures performed at the site of osteomyelitis which require a second stage reconstruction with impacted bone grafting techniques

Introduction and Objective. In recent years, along with the extending longevity of patients and the increase in their functional demands, the number of annually performed RSA and the incidence of complications are also increasing. When a complication occurs, the patient often needs multiple surgeries to restore the function of the upper limb. Revision implants are directly responsible for the critical reduction of the bone stock, especially in the shoulder. The purpose of this paper is to report the use of allograft bone to restore the bone stock of the glenoid in the treatment of an aseptic glenoid component loosening after a reverse shoulder arthroplasty (RSA). Materials and Methods. An 86-years-old man came to our attention for aseptic glenoid component loosening after RSA. Plain radiographs showed a complete dislocation of the glenoid component with 2 broken screws in the neck of glenoid. CT scans confirmed the severe reduction of the glenoid bone stock and critical bone resorption and were used for the preoperative planning. To our opinion, given the critical bone defect, the only viable option was revision surgery with restoration of bone stock. We planned to use a bone graft harvested from distal bone bank femur as component augmentation. During the revision procedure the baseplate with a long central peg was implanted “on table” on the allograft and an appropriate osteotomy was made to customize the allograft on the glenoid defect according to the CT-based preoperative planning. The Bio-component was implanted with stable screws fixation on residual scapula. We decided not to replace the humeral component since it was stable and showed no signs of mobilization. Results. The new bio-implant was stable, and the patient gained a complete functional recovery of the shoulder. The scheduled radiological assessments up to 12 months showed no signs of bone resorption or mobilization of the glenoid component. Conclusions. The use of bone allograft in revision surgery after a RSA is a versatile and effective technique to treat severe glenoid bone loss and to improve the global stability of the implant. Furthermore, it represents a viable alternative to autologous graft since it requires shorter operative times and reduces graft site complications. There are very few data available regarding the use of allografts and, although the first studies are encouraging, further investigation is needed to determine the biological capabilities of the transplant and its validity in complex revisions after RSA

Allograft bone is widely used in orthopaedic surgery, but peri-operative infection of the graft remains a common and disastrous complication. The efficacy of systemic prophylactic antibiotics is unproven, and since the graft is avascular it is likely that levels of antibiotic in the graft are low. Using an electrical potential to accelerate diffusion of antibiotics into allograft bone, high levels were achieved in specimens of both sheep and human allograft. In human bone these ranged from 187.1 mg/kg in endosteal (. sd. 15.7) to 124.6 (. sd. 46.2) in periosteal bone for gentamicin and 31.9 (. sd. 8.9) in endosteal and 2.9 (. sd. 1.1) in periosteal bone for flucloxacillin. The antibiotics remained active against bacteria in vitro after iontophoresis and continued to elute from the allograft for up to two weeks. Structural allograft can be supplemented directly with antibiotics using iontophoresis. The technique is simple and inexpensive and offers a potential means of reducing the rate of peri-operative infection in allograft surgery. Iontophoresis into allograft bone may also be applicable to other therapeutic compounds

Bone allograft is the most widely accepted approach in treating patients suffering from large segmental bone defect regardless of the advancement of synthetic bone substitutes. However, the long-term complications of allograft application in term of delayed union and nonunion were reported due to the stringent sterilization process. Our previous studies demonstrated that the incorporation of magnesium ions (Mg2+) into biomaterials could significantly promote the gene up-regulation of osteoblasts and new bone formation in animal model. Hence, our group has proposed to establish an Mg2+ enriched tissue microenvironment onto bone allograft so as to enhance the bone healing. The decellularization and gamma irradiation process were performed on bovine bone allograft and followed by magnesium plasma treatment. To evaluate the biocompatibility and bioactivity, materials characterizations, in vitro and in vivo studies were conducted, respectively. Mg composite layer on bone surface ranged from 500nm to ∼800nm thick. The cell viability on magnesium enriched allograft was significantly higher than that of the control. The ALP gene expression of hTMSCs in the group of PIII&D treated samples was highly up-regulated. The bone regeneration ability of Mg modified bone allograft implanted in animal model was significantly superior than the control after 2-month post-operation

Impacted bone allograft is often used in revision joint replacement. Hydroxyapatite granules have been suggested as a substitute or to enhance morcellised bone allograft. We hypothesised that adding osteogenic protein-1 to a composite of bone allograft and non-resorbable hydroxyapatite granules (ProOsteon) would improve the incorporation of bone and implant fixation. We also compared the response to using ProOsteon alone against bone allograft used in isolation. We implanted two non-weight-bearing hydroxyapatite-coated implants into each proximal humerus of six dogs, with each implant surrounded by a concentric 3 mm gap. These gaps were randomly allocated to four different procedures in each dog: 1) bone allograft used on its own; 2) ProOsteon used on its own; 3) allograft and ProOsteon used together; or 4) allograft and ProOsteon with the addition of osteogenic protein-1. After three weeks osteogenic protein-1 increased bone formation and the energy absorption of implants grafted with allograft and ProOsteon. A composite of allograft, ProOsteon and osteogenic protein-1 was comparable, but not superior to, allograft used on its own. ProOsteon alone cannot be recommended as a substitute for allograft around non-cemented implants, but should be used to extend the volume of the graft, preferably with the addition of a growth factor

Abstract. Introduction. Bone grafts are utilised in a range of surgical procedures, from joint replacements to treatment of bone loss resulting from cancer. Decellularised allograft bone is a regenerative, biocompatible and immunologically safe potential source of transplant bone. Objectives. To compare the structural and biomechanical parameters of decellularised and unprocessed (cellular) trabecular bone from the human femoral head (FH) and tibial plateau (TP). Methods. Bone pins were harvested from 10 FHs and 11 TPs (27, 34 respectively). Pins were decellularised (0.1% w/v sodium dodecyl sulphate) or retained as cellular controls. QA testing was carried out to assess protocol efficacy (total DNA and histological analysis). Cellular and decellularised FH (n=7) and TP (n=10) were uCT scanned. Material density (MD); apparent density (BV/TV); trabecular connectivity; trabecular number; trabecular thickness (Tb-t) and trabecular spacing were measured. Pins were then compression tested to determine ultimate compressive stress (UCS), Young's modulus and 0.2% proof stress. Results. Total DNA levels of decellularised bone were below 50 ng.mg. −1. dry weight. Cell nuclei and marrow were largely removed. No significant differences in properties were found between decellularised and cellular bone from either anatomical region (p>0.05, Mann-Whitney). No significant differences in biomechanical properties were found between cellular FH and cellular TP (p>0.05) though significant differences in structural properties were found (MD: TP>FH, p=0.001; BV/TV: FH>TP, p=0.001; and Tb-t: FH>TP, p=0.005). Significant differences were found between decellularised FH and decellularised TP (UCS: FH>TP, p=0.001; Young's modulus: FH>TP, p=0.002; proof stress; FH>TP, p=0.001; MD: TP>FH, p<0.001; BV/TV: FH>TP, p<0.001 and Tb-t: FHT>P p<0.001. Conclusion. Decellularisation did not affect the properties of human trabecular bone. Differences were found between the mechanical and structural properties of decellularised FH and TP which could facilitate stratified bone grafts for different applications. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

We used a canine intercalary bone defect model to determine the effects of recombinant human osteogenic protein 1 (rhOP-1) on allograft incorporation. The allograft was treated with an implant made up of rhOP-1 and type I collagen or with type I collagen alone. Radiographic analysis showed an increased volume of periosteal callus in both test groups compared with the control group at weeks 4, 6, 8 and 10. Mechanical testing after 12 weeks revealed increased maximal torque and stiffness in the rhOP-1 treated groups compared with the control group. These results indicate a benefit from the use of an rhOP-1 implant in the healing of bone allografts. The effect was independent of the position of the implant. There may be a beneficial clinical application for this treatment

This study investigates the use of porous biphasic ceramics as graft extenders in impaction grafting of the femur during revision hip surgery. Impaction grafting of the femur was performed in four groups of sheep. Group one received pure allograft, group two 50% allograft and 50% BoneSave, group three 50% allograft and 50% BoneSave type 2 and group four 10% allograft and 90% BoneSave as the graft material. Function was assessed using an index of pre- and post-operative peak vertical ground reaction force ratios. Changes in bone mineral density were measured by dual energy X ray absorptiometry (DEXA) scanning. Loosening and subsidence were assessed radiographically and by histological examination of the explanted specimens. There was no statistically significant difference between the four groups after 18 months of unrestricted functional loading for all outcome measures

From November 1994 to March 1997, we harvested 137 grafts of the femoral head from 125 patients for donation during total hip arthroplasty according to the guidelines of the American Associations of Tissue Banks (AATB) and the European Association of Musculo-Skeletal transplantation (EAMST). In addition to the standards recommended by these authorities, we performed histopathological examination of a core biopsy of the retrieved bone allograft and of the synovium. Of the 137 allografts, 48 (35.0%) fulfilled all criteria and were free for donation; 31 (22.6%) were not regarded as suitable for transplantation because the serological retests at six months were not yet complete and 58 (42.3%) were discarded because of incomplete data. Of those discarded, five showed abnormal histopathological findings; three were highly suspicious of low-grade B-cell lymphoma, one of monoclonal plasmacytosis and the other of non-specific inflammation of bone marrow. However, according to the standards of the AATB or EAMST they all met the criteria and were eligible for transplantation. Our findings indicate that the incidence of abnormal histopathology in these retrieved allografts was 3.6%. Since it is essential to confirm the quality of donor bones in bone banking, we advise that histopathological screening of donor bone should be performed to exclude abnormal allografts

Summary Statement. Supercritical fluid (SCF) sterilization produces clean and osteoconductive allograft bone capable of healing a critical-sised bony defect. SCF treated graft induces an increased anabolic response and decreased catabolic reponse compared to gamma irradiated graft. Introduction. Clinically, allogeneic bone graft is used extensively because it avoids the donor site morbidity associated with autograft. However, there are concerns over the optimal sterilization method to eliminate immunological risks whilst maintaining the biological efficacy of the graft. This study compared the effect of Supercritical fluid (SCF) sterilization and gamma irradiation on the osteoconductivity of allograft bone in a bilateral critical-sised defect rabbit model. Methods. Cortical-cancellous allograft bone was milled, defatted and terminally sterilised with either gamma irradiation at 25kGy or SCF treatment. The graft was then implanted bilaterally into a critical-sised metaphyseal defect in 10 New Zealand White rabbits (n=5 sites per time point per group). Osteoconductivity was evaluated at 2 and 4 weeks to measure the early inflammatory response and early new bone formation respectively, using X-ray, CT, and both qualitative and quantitative histology and immunohistochemistry (Alkaline Phosphatase and Cathepsin-K). Results. Both grafts were well tolerated and osteoconductive. At 2 weeks, there were significant reductions in bone volume and density in the gamma irradiated graft compared to the SCF treated graft as measured by CT. Inside the defect this corresponded with a greater inflammatory response in the gamma irradiated graft, with a less organised fibrous tissue infiltration and mild granuloma reaction. Conversely, the SCF group had a highly organised and densely packed fibrous tissue infiltration around the allograft chips. Immunohistochemistry results supported these findings with an up-regulation in the expression and distribution of Cathepsin-K in the gamma irradiation group; while Alkaline Phosphatase expression was higher in the SCF group. At 4 weeks, resorptive behavior predominated in both groups. Radiographic and CT results detected no significant difference between groups. Histology at 4 weeks showed larger bone chips were undergoing substantial remodeling with areas of simultaneous osteoclastic resorption and osteoblastic new bone formation. Smaller allograft chips and areas of new bone formation were infiltrated by fibrous tissue and undergoing osteoclastic resorption. Quantitative immunohistochemistry showed an up-regulation of Cathepsin-K expression in both groups from 2 to 4 weeks. At both time points Cathepsin-K expression was higher in the gamma irradiated graft compared to the SCF group. This was greatest at 2 weeks where there was a substantial 82% increase in expression which was reduced to a 38% discrepancy at 4 weeks. Alkaline Phosphatase expression was greater in the SCF group at both time-points. Discussion/Conclusion. Allograft bone sterilised with either gamma irradiation or SCF treatment was osteoconductive and capable of healing a critical-sised defect in a rabbit. Gamma irradiated allografts elicited an acute inflammatory reaction when implanted which increased the amount graft resorption compared to the SCF treated bone. Increased osteoclastic resorption may be a concern for structural graft applications leaving the graft more susceptible to premature failure. SCF sterilization produced a clean, highly biocompatible graft with increased anabolic activity compared to gamma irradiation which may facilitate earlier healing clinically. These results suggest that SCF sterilization has considerable expediency for allograft processing and may facilitate more optimal extraction of the inherent properties of the graft compared to current practices

This study explored the relationship between the initial stability of the femoral component and penetration of cement into the graft bed following impaction allografting. Impaction allografting was carried out in human cadaveric femurs. In one group the cement was pressurised conventionally but in the other it was not pressurised. Migration and micromotion of the implant were measured under simulated walking loads. The specimens were then cross-sectioned and penetration of the cement measured. Around the distal half of the implant we found approximately 70% and 40% of contact of the cement with the endosteum in the pressure and no-pressure groups, respectively. The distal migration/micromotion, and valgus/varus migration were significantly higher in the no-pressure group than in that subjected to pressure. These motion components correlated negatively with the mean area of cement and its contact with the endosteum. The presence of cement at the endosteum appears to play an important role in the initial stability of the implant following impaction allografting

Soaking bone grafts in a bisphosphonate solution before implantation can prevent their resorption and increase the local bone density in rats and humans. However, recent studies suggest that pre-treatment of allografts with bisphosphonate can prevent bone ingrowth into impaction grafts. We tested the hypothesis that excessive amounts of bisphosphonate would also cause a negative response in less dense grafts. We used a model where non-impacted metaphyseal bone grafts were randomised into three groups with either no bisphosphonate, alendronate followed by rinsing, and alendronate without subsequent rinsing, and inserted into bone chambers in rats. The specimens were evaluated histologically at one week, and by histomorphometry and radiology at four weeks. At four weeks, both bisphosphonate groups showed an increase in the total bone content, increased newly formed bone, and higher radiodensity than the controls. In spite of being implanted in a chamber with a limited opportunity to diffuse, even an excessive amount of bisphosphonate improved the outcome. We suggest that the negative results seen by others could be due to the combination of densely compacted bone and a bisphosphonate. We suggest that bisphosphonates are likely to have a negative influence where resorption is a prerequisite to create space for new bone ingrowth

Summary. The BMP-2 content and bone forming potential of 2 leading allograft products (OsteoAMP® and Osteocel® Plus) was tested across 3 commercially available lots. Surprisingly, there was no BMP-2 content associated with the cells contained within Osteocel® Plus. OsteoAMP® contained greater than 1000 times the overall BMP-2 content than Osteocel® Plus. Correspondingly, Osteocel® Plus did not form new bone at any timepoint in the 12 week in vivo study while OsteoAMP® had increasing new bone formation at each sequential timepoint. Interestingly, the highest cellularity of Osteocel® Plus was just prior to implant at t. 0. , decreasing at each timepoint, decreasing further at the terminal endpoint of the study at 12 weeks (82% of cells had died or migrated). Conversely, the cellularity of OsteoAMP® increased at each timepoint. Introduction. Implants containing living cells are often characterised by the orthobiologics industry as ‘osteogenic’. The positive function and ultimate fate of these cells has been assumed with little to no proof of efficacy. In this study we compare the bone forming ability of the market leading stem cell product claiming osteoinductivity as well as osteogenicity, Osteocel® Plus, against the market leading allograft derived growth factor product, OsteoAMP® which claims osteoinductivity but contains no viable cells. The goal of the study is to determine if a cellular product will form new bone or produce a false positive when evaluated histomorphometrically using an osteoinductive control over time in vivo. Additionally, the osteoinductive potential from each product will be quantified by in vitro by measurement of BMP-2 content via ELISA. Methods. Three different lots of each OsteoAMP® and Osteocel® Plus were implanted by an independent lab into muscle pouches of athymic rats. Implants were assessed for bone formation using H&E histology at time of implant, 1 day, 2w, 4w, 6w, 8w, and 12w. Histomorphometric measurements were done using Image J (NIH) using four sections per implant per timepoint (n=12). Each lot of both products was also digested in water, hydrochloric acid, and guanidine-hydrochloride (Gua-HCl) to facilitate BMP-2 content quantification via ELISA (R&D Systems). The extracts were intended to independently measure cellular, mineral, and collagen phase content of BMP-2. All extracts were analyzed by ELISA independently to characterise the source of osteoinductivity and the resulting release profile in vivo. Results. With each subsequent timepoint, all lots of Osteocel® Plus exhibited increasing osteonecrosis with increasing time. By the terminal 12 week timepoint used in this study, 82% of living bone that was implanted for Osteocel® Plus had died or migrated away from the implant site. In contrast, new bone formation and cellularity increased with OsteoAMP® at each timepoint, still increasing at the terminal 12 week endpoint of this study. The BMP-2 results support the bone formation in vivo. Neither of the 3 Osteocel® Plus lots registered any BMP-2 from the cells on ELISA, nor was there any free BMP-2 that leached out of the product. The mineral phase of Osteocel® Plus exhibited traces of BMP-2 for only one of the 3 donors with an average of 0.04 ng/g for all three donors. The protein phase of Osteocel® Plus had the highest concentration of BMP-2 at 0.63 ng/g BMP-2. For all three lots, OsteoAMP® showed no leaching of BMP-2 after exposure to water and a BMP-2 content in the mineral phase of 50.85 ng/g. The collagen phase of OsteoAMP® had the highest concentration of BMP-2 in all groups tested at 915.54 ng/g. Discussion. The results in this study would suggest that orthobiologic implants that contain living cells and claim osteogenic properties do not maintain viable cells over time and did not form bone. Similarly, the results would indicate the living cells do not contribute to osteoinductivity. In contrast, the higher BMP-2 content and osteoinductive property exhibited by OsteoAMP® was a stronger producer of new bone

Dura mater is a thick membrane that is the outermost of the three layers of the meninges that surround the brain and spinal cord. Appropriate dural healing is crucial to prevent cerebrospinal fluid leaks but the entire process has been barely understood so far. Understanding of dural healing and tissue neoformation over the dural grafts, which are usually used for duraplasty, is still partial. Therefore, implantation of decellular dura mater (DM) to recipient from different donor and vitalization with recipient”s mesenchymal stem cells for the treatment of tissue on transplantation process is significant approach. This approach prevents immunological reactions and provides long-term stabilization. According to this study, it is believed that this approach will provide DM healing and become crucial in DM transplantation. The aim of this study was to develop a new construct by tissue engineering of the human DM based on a decellular allograft. Thus human DM collected from forensic medicine and decellularized using the detergent sodium dodecyl sulfate (SDS) in the multiple process of physical, enzimatic and chemical steps. Decellularization were exposing the tissue to freeze-thaw cycles, incubation in hypotonic tris-HCl buffer, 0.1% (w/v) SDS in hypotonic buffer and hypertonic buffer followed by disinfection using 0.1% (v/v) peracetic acid and final washing in phosphate-buffered saline. As a result of all these processes, cellular components of DM were removed by preserving the extracellular matrix without any significant loss in mechanical properties. Based on the histological analysis of the decellularized DM revealed the absence of visible whole cells. Collagen and glycosaminoglycan (GAG) contents of decellular DM evaluated histological staining by Masson Trichrome and Alcian blue respectively. Also biochemical tests were carried out by spectrophotometry (Quickzym Biosciences, The Netherlands) and total GAG content were analyzed by 1.9 dimethylmethylene blue assay. The histoarchitecture was unchanged, and there were no significant changes of total collagen and GAG content. Biomechanical properties were determined by tensile tests, which has confirmed the retention of biomechanical properties following decellularization. The mean tensile strengths were 7,424±4,20 MPa for control group, 5,254±2,068 MPa for decellularization group. There was no statistically significant difference between tensile strength (p=0,277) and tissue thickness (p=0, 520) for both group. In conclusion, this study has developed biomechanically functional decellularized DM scaffold for use in DM repair. In addition, this study is a part of the progressing study and additional studies investigating the biocompatibility performance of the decellularized DM scaffold and there is need for in vivo studies. Keywords. Dura mater, Decellularization, Allografts, Scaffolds, Tissue Engineering

We analysed the histological findings in 1146 osteoarthritic femoral heads which would have been considered suitable for bone-bank donation to determine whether pathological lesions, other than osteoarthritis, were present. We found that 91 femoral heads (8%) showed evidence of disease. The most common conditions noted were chondrocalcinosis (63 cases), avascular necrosis (13), osteomas (6) and malignant tumours (one case of low-grade chondrosarcoma and two of well-differentiated lymphocytic lymphoma). There were two with metabolic bone disease (Paget’s disease and hyperparathyroid bone disease) and four with inflammatory (rheumatoid-like) arthritis. Our findings indicate that occult pathological conditions are common and it is recommended that histological examination of this regularly used source of bone allograft should be included as part of the screening protocol for bone-bank collection