Subchondroplasty Bone Substitute Material (BSM) Histological Analysis after Total Knee Arthroplasty: A Case Series

In our series of 227 patients who underwent prior Subchondroplasty of the knee wiht bone substitute material (BSM) we had the opportunity to review 4 cases which returned for conversion to Total Knee Arthroplasty (TKA). The average time to convert to a TKA was 23.5 months (18-35 months).

Temporal response of an injectable calcium phosphate material in a critical size defect

Background Calcium phosphate-based bone graft substitutes are used to facilitate healing in bony defects caused by trauma or created during surgery. Here, we present an injectable calcium phosphate-based bone void filler that has been purposefully formulated with hyaluronic acid to offer a longer working time for ease of injection into bony defects that are difficult to access during minimally invasive surgery. Methods The bone substitute material deliverability and physical properties were characterized, and in vivo response was evaluated in a critical size distal femur defect in skeletally mature rabbits to 26 weeks. The interface with the host bone, implant degradation, and resorption were assessed with time. Results The calcium phosphate bone substitute material could be injected as a paste within the working time window of 7–18 min, and then self-cured at body temperature within 10 min. The material reached a maximum ultimate compressive strength of 8.20 ± 0.95 MPa, similar to trabecular bone. The material was found to be biocompatible and osteoconductive in vivo out to 26 weeks, with new bone formation and normal bone architecture observed at 6 weeks, as demonstrated by histological evaluation, microcomputed tomography, and radiographic evaluation. Conclusions These findings show that the material properties and performance are well suited for minimally invasive percutaneous delivery applications.

The use of solvent-preserved human and bovine cancellous bone blocks for lateral defect augmentation - an experimental controlled study in vivo

Background The aim of this study was to compare new bone formation, resorbed bone matrix, and fibrous enclosed residual bone substitute material in laterally augmented alveolar bone defects using allogeneic, pre-treated and cleaned human bone blocks (tested in dogs, therefore considered to be xenogeneic), and pre-treated and cleaned bovine cancellous bone blocks, both with and without a collagen membrane in order to evaluate their augmentative potential. Methods Thirty-two critical size horizontal defects were prepared in the mandible of 4 adult foxhound dogs (8 per dog, 4 on each side). After 3 months of healing, the defects were laterally augmented in a split-mouth-design with either human (HXB) or bovine solvent-preserved bone blocks (BXB). Afterwards, defects were randomly covered with a bovine collagenous membrane (HXB + M, BXB + M). After a healing interval of 6 months, percentages of new bone formation, resorbed bone matrix, and fibrous enclosed residual bone substitute material were compared. Results Results showed little new bone formation of up to 3.7 % in human bone blocks (HXB 3.7 % ± 10.2, HXB + M 0.3 %± 0.4, BXB, 0.1 % ± 0.8, BXB + M 2.6 % ± 3.2, p = > 0.05). Percentages of fibrous encapsulation were higher in human bone blocks than in bovine bone blocks (HXB 71.2 % ± 8.6, HXB + M 73.71 % ± 10.6, BXB, 60.5 % ± 27.4, BXB + M 52.5 % ± 28.4, p = > 0.05). Resorption rates differed from 44.8 % in bovine bone blocks covered with a membrane to 17.4 % in human bone blocks (HXB 17.4 % ± 7.4, HXB + M 25.9 % ± 10.7, BXB, 38.4 % ± 27.2, BXB + M 44.8 % ± 29.6, p = > 0.05). The use of additional membranes did not significantly affect results. Conclusions Within its limitations, results of this study suggest that solvent-preserved xenogenic human and bovine bone blocks are not suitable for lateral bone augmentation in dogs. Furthermore, defect coverage with a membrane does not positively affect the outcome.

Synthesis and Characterization of PVA Assisted Sr-Hydroxyapatite Using Hydrothermal Coupled Microemulsion Method

Hydroxyapatite is a bioceramic material and it is one of the most important inorganic compounds which are extensively used in several forms as a bone substitute material. Hydroxyapatite is chemically represented as (Ca10(PO4)6(OH)2), and is chemically and crystallographically similar to the human hard tissue. The hydroxyapatite nanoparticle is mainly used in orthopaedic and dental applications due to its properties of bioactivity, osteoconduction, biocompatibility and non-toxicity. In this research work, poly vinyl alcohol assisted strontium substituted hydroxyapatite nano powders was synthesised by conventional hydrothermal coupled microemulsion method using dimethyl sulfoxide and hexane. It is well known that strontium stimulates bone formation, reduction bone resorption and it is also used to osteoporosis diseases, while poly vinyl alcohol (PVA) helps in controlling the morphology and it is beneficial for artificial bone formation and possess excellent bioactivities properties. The structure, chemical composition and morphology were investigated by different techniques such as XRD, FTIR, SEM and MTT assay. The results indicated that the poly vinyl alcohol assisted Sr substituted hydroxyapatite nanoparticle has a uniform spherical morphology, smaller particle size and with no impurities. The biomedical application studies of the as-synthesised material are yet to be studied.

Finite memory model of bone healing in analysis of moving interface between mandible tissue and bone substitute material after tooth implant application

A previous bone remodelling model was presented elsewhere [30], and in the present paper, the same model was tested with new conditions; an interaction between bone tissue, bone substitute material and a dental implant was considered. The bone substitute material was assumed to be dead tissue, which does not synthesizes neither absorbs bone tissue, and it was considered, as well, resolvable. A moving border between the bone substitute material and the bone tissue was studied. The border moved as the newly synthesised bone tissue took over the bone substitute material. After the numerical calculations of time-steps, the whole bone substitute material was replaced by normal bone tissue and the implant was fixed in place only by bone tissue. Dynamical studies of the interaction of bone tissue and implant are used to improved implant design considering different factors, in this case, the presence of bone substitute material helping to fix the implant.

In Vivo Analysis of the Biocompatibility and Bone Healing Capacity of a Novel Bone Grafting Material Combined with Hyaluronic Acid

The present in vivo study analyses both the inflammatory tissue reactions and the bone healing capacity of a newly developed bone substitute material (BSM) based on xenogeneic bone substitute granules combined with hyaluronate (HY) as a water-binding molecule. The results of the hyaluronate containing bone substitute material (BSM) were compared to a control xenogeneic BSM of the same chemical composition and a sham operation group up to 16 weeks post implantationem. A major focus of the study was to analyze the residual hyaluronate and its effects on the material-dependent healing behavior and the inflammatory tissue responses. The study included 63 male Wistar rats using the calvaria implantation model for 2, 8, and 16 weeks post implantationem. Established and Good Laboratory Practice (GLP)-conforming histological, histopathological, and histomorphometrical analysis methods were conducted. The results showed that the new hyaluronate containing BSM was gradually integrated within newly formed bone up to the end of the study that ended in a condition of complete bone defect healing. Thereby, no differences to the healing capacity of the control BSM were found. However, the bone formation in both groups was continuously significantly higher compared to the sham operation group. Additionally, no differences in the (inflammatory) tissue response that was analyzed via qualitative and (semi-) quantitative methods were found. Interestingly, no differences were found between the numbers of pro- and anti-inflammatory macrophages between the three study groups over the entire course of the study. No signs of the HY as a water-binding part of the BSM were histologically detectable at any of the study time points, altogether the results of the present study show that HY allows for an optimal material-associated bone tissue healing comparable to the control xenogeneic BSM. The added HY seems to be degraded within a very short time period of less than 2 weeks so that the remaining BSM granules allow for a gradual osteoconductive bone regeneration. Additionally, no differences between the inflammatory tissue reactions in both material groups and the sham operation group were found. Thus, the new hyaluronate containing xenogeneic BSM and also the control BSM have been shown to be fully biocompatible without any differences regarding bone regeneration.

Gene expression, immunohistochemical and microarchitectural evaluation of bone formation around two implant surfaces placed in bone defects filled or not with bone substitute material

Objective The aim of this study is to evaluate through gene expression, immunohistochemical and microtomographic (micro-CT) analysis the response of peri-implant bone tissue around titanium implants with different surface treatments, placed in bone defects filled or not with bone substitute materials. In addition, to investigate the hypothesis that porous-hydrophilic surface induces a faster bone formation. Materials and methods Twenty-six animals were divided into two groups according to implant surface treatment. In each tibia, a bone defect was created followed by the placement of one implant. On the left tibia, the defect was filled with blood clot (BC), and on the right tibia, the defect was filled with biphasic hydroxyapatite/β-tricalcium-phosphate (HA/TCP) generating four subgroups: BC-N: bone defect filled with blood clot and porous surface titanium implant installed; BC-A: bone defect filled with blood clot and porous-hydrophilic surface titanium implant installed; HA/TCP-N: bone defect filled with bone substitute material and porous surface titanium implant installed; and HA/TCP-A: bone defect filled with bone substitute material and porous-hydrophilic surface titanium implant installed. The animals were submitted to euthanasia at 15, 30, and 60 days after implant installation. The expression of two genes was evaluated: RUNX2 and BSP. Immunohistochemical analyses were performed for detection of RUNX2, OPN, OCN, OPG, and RANKL antibodies and bone matrix proteins. Finally, four parameters were chosen for micro-CT analysis: trabecular number, separation and thickness, and connectivity density. Results Descriptive analysis showed similar findings among the experimental groups. Moreover, porous-hydrophilic surfaces presented a higher expression of RUNX2, which is probably an indicative of better osteogenesis; although the data from this study may be considered an insufficient support for a concrete statement. Conclusion Porous hydrophilic surface can improve and accelerate protein expression and bone formation.

Collagenated Synthetic Bone Substitute Material for Sinus Floor Elevation at Sites with a Perforated Schneiderian Membrane

Schneiderian membrane perforation (SMP) is the most common complication during sinus floor elevation (SFE). Conventional methods to repair SMP, such as using a collagen barrier, may be clinically demanding. The aim of the present study was to compare the effects of collagenated bone substitute materials with and without a collagen barrier to repair SMP during SFE in terms of new bone formation and dimensional stability. In 12 rabbits, intentional SMP was made during bilateral SFE. The rabbits were randomly assigned under two groups: the control group, in which the sinus was repaired with a collagen barrier, and the test group, in which the sinus was repaired without a collagen barrier. Collagenated bone substitute material was grafted in both groups. Healing periods of 2 weeks and 4 weeks were provided in both groups. There were no adverse clinical events. Histology revealed that the Schneiderian membrane had atrophied with loss of cilia and serous glands in both groups at 4 weeks. Histomorphometry revealed that the newly formed bone (test: 0.42 ± 0.17 mm2, control: 0.36 ± 0.18 mm2 at 2 weeks; test: 1.21 ± 0.36 mm2, control: 1.23 ± 0.55 mm2 at 4 weeks) or total augmented area did not significantly differ between the two groups at either time points (p > 0.05). In conclusion, collagenated bone substitute material without a collagen barrier demonstrated similar new bone formation and dimensional stability as that with a collagen barrier in repairing SMP.