No effect of platelet-rich plasma with frozen or processed bone allograft around noncemented implants

Microarchitectural properties of compacted cancellous bone allografts: A morphology micro-computed tomography analysis

Massive bone loss poses a significant challenge in defect reconstruction. The use of compacted allografts is a valuable technique to reconstruct bone stock. This study aimed to assess the impact of compression on the microstructure of native cancellous bone chips with a micro-CT analysis. Bone samples were harvested from 15 femoral heads donated by patients who underwent total hip arthroplasty. Bone chips were prepared using a bone mill. All samples with the same weight were compressed by 25% and 50% of their original volume and subsequently scanned with a micro-CT scanner to determine the microarchitectural morphology of the bone chips. Uniaxial compression test was carried out before and after a standardized compaction procedure. Comparing the samples without compaction to 50%, the number of trabeculae doubled, the volume ratio doubled, and the trabeculae spacing was reduced, showing voids of 800 μm on average. The number of interlocking possibilities tripled, while no differences were seen in the trabeculae morphology. Uniaxial compression test showed a yield limit after compaction of 0.125 MPa. Interlocking might occur three times more with a denser material than in a non-compacted sample. The increase in density comparable to manual intraoperative compaction did not lead to significant fragmentation of the allograft material. The assessed microarchitecture should, therefore, reassemble the intraoperative situation during a manual bone impaction procedure.

Clinical Effect of Platelet-Rich Fibrin Combined with BIO-GENE Artificial Bone Meal in Bone Defects After Jaw Cyst Surgery

Purpose

To compare the clinical repair effects of leaving the defect empty and using Platelet-Rich Fibrin (PRF) combined with BIO-GENE artificial bone powder in patients with bone defects 6 months after jaw cystectomy.

Patients and Methods

From June 2021 to June 2022, 70 patients who were admitted to the Department of Stomatology, Affiliated Hospital of Yanbian University, and were diagnosed with jaw cysts postoperatively were selected. All of the patients were divided into two groups according to random method, among which 35 patients who underwent cystectomy alone were recorded as group A, which served as blank control; 35 patients who underwent cystectomy and PRF combined with BIO-GENE artificial bone meal repaired bone defects during the same period were recorded as group B. 3D Slicer 5.0.3 software was used to reconstruct Cone Beam Computed Tomography (CBCT) after operation. In this study, the preoperative and postoperative CBCT data of the patients were analyzed using 3D Slicer 5.0.3 software in DICOM format to calculate the cleft volume before surgery and the newly formed bone volume after surgery. The osteogenesis rate was measured based on these calculations.The bone formation percentage in the bone defect area was recorded at 6 months, and the clinical curative effects of the two groups were compared.

Results

After 6 months of surgery, the patients showed varying degrees of restoration in the jaw cyst area.The osteogenesis rate at 6 months in group A was 76.06±13.38%, while group B had a rate of 92.87±5.72%.The CBCT values in group B were higher than those in group A at 6 months post-surgery (P<0.05), t=-6.84.Group A and Group B showed a statistically significant difference.

Conclusion

Compared with simple cystectomy, PRF combined with BIO-GENE artificial bone powder has a better effect on the speed of bone repair after cystectomy within 6 months and provides more favorable effects for the repair of postoperative dentition defects, and provides support to repair teeth after defects such as dental implants.

Alteration of blood clot structures by interleukin-1 beta in association with bone defects healing

The quality of hematomas are crucial for successful early bone defect healing, as the structure of fibrin clots can significantly influence the infiltration of cells, necessary for bone regeneration, from adjacent tissues into the fibrin network. This study investigated if there were structural differences between hematomas from normal and delayed healing bone defects and whether such differences were linked to changes in the expression of IL-1β. Using a bone defect model in rats, we found that the hematomas in the delayed healing model had thinner fibers and denser clot structures. Moreover, IL-1β protein levels were significantly higher in the delayed healing hematomas. The effects of IL-1β on the structural properties of human whole blood clots were evaluated by thrombelastograph (TEG), scanning electronic microscopy (SEM), compressive study, and thrombolytic assays. S-nitrosoglutathione (GSNO) was applied to modulate de novo hematoma structure and the impact on bone healing was evaluated in the delayed healing model. We found that GSNO produced more porous hematomas with thicker fibers and resulted in significantly enhanced bone healing. This study demonstrated that IL-1β and GSNO had opposing effects on clot architecture, the structure of which plays a pivotal role in early bone healing.

3D perfusion bioreactor-activated porous granules on implant fixation and early bone formation in sheep

Early fixation of total joint arthroplasties is crucial for ensuring implant survival. An alternative bone graft material in revision surgery is needed to replace the current gold standard, allograft, seeing that the latter is associated with several disadvantages. The incubation of such a construct in a perfusion bioreactor has been shown to produce viable bone graft materials. This study aimed at producing larger amounts of viable bone graft material (hydroxyapatite 70% and β-tricalcium-phosphate 30%) in a novel perfusion bioreactor. The abilities of the bioreactor-activated graft material to induce early implant fixation were tested in a bilateral implant defect model in sheep, with allograft as the control group. Defects were bilaterally created in the distal femurs of the animals, and titanium implants were inserted. The concentric gaps around the implants were randomly filled with either allograft, granules, granules with bone marrow aspirate or bioreactor-activated graft material. Following an observation time of 6 weeks, early implant fixation and bone formation were assessed by micro-CT scanning, mechanical testing, and histomorphometry. Bone formations were seen in all groups, while no significant differences between groups were found regarding early implant fixation. The microarchitecture of the bone formed by the synthetic graft materials resembled that of allograft. Histomorphometry revealed that allograft induced significantly more bone and less fibrous tissue (p < 0.05). In conclusion, bone formation was observed in all groups, while the bioreactor-activated graft material did not reveal additional effects on early implant fixation comparable to allograft in this model. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2465-2476, 2017.

Assessment of activated porous granules on implant fixation and early bone formation in sheep

Background/Objective

Despite recent progress in regeneration medicine, the repair of large bone defects due to trauma, inflammation and tumor surgery remains a major clinical challenge. This study was designed to produce large amounts of viable bone graft materials in a novel perfusion bioreactor to promote bone formation.

Methods

Cylindrical defects were created bilaterally in the distal femurs of sheep, and titanium implants were inserted. The concentric gap around the implants was randomly filled either with allograft, granules, granules with bone marrow aspirate (BMA) or bioreactor activated granule (BAG). The viable BAG consisted of autologous bone marrow stromal cells (BMSCs) seeded upon porous scaffold granules incubated in a 3D perfusion bioreactor for 2 weeks prior to surgery. 6 weeks after, the bone formation and early implant fixation were assessed by means of micro-CT, histomorphometry, and mechanical test.

Results

Microarchitectural analysis revealed that bone volume fraction and trabecular thickness in the allograft were not statistically different than those (combination of new bone and residue of granule) in the other 3 groups. The structure of the allograft group was typically plate-like, while the other 3 groups were combination of plate and rod. Histomorphometry showed that allograft induced significantly more bone and less fibrous tissue in the concentric gap than the other 3 granule groups, while the bone ingrowth to implant porous surface was not different. No significant differences among the groups were found regarding early implant mechanical fixation.

Conclusion

In conclusion, despite nice bone formation and implant fixation in all groups, bioreactor activated graft material did not convincingly induce early implant fixation similar to allograft, and neither bioreactor nor by adding BMA credited additional benefit for bone formation in this model.

Three-dimensional virtual bone bank system for selecting massive bone allograft in orthopaedic oncology

PURPOSE

Although structural bone allografts have been used for years to treat large defects caused by tumour or trauma, selecting the most appropriate allograft is still challenging. The objectives of this study were to: (1) describe the establishment of a visual bone bank system and workflow of allograft selection, and (2) show mid-term follow-up results of patients after allograft implantation.

METHODS

Allografts were scanned and stored in Digital Imaging and Communications in Medicine (DICOM) files. Then, image segmentation was conducted and 3D model reconstructed to establish a visual bone bank system. Based on the volume registration method, allografts were selected after a careful matching process. From November 2010 to June 2013, with the help of the Computer-assisted Orthopaedic Surgery (CAOS) navigation system, the allografts were implanted in 14 patients to fill defects after tumour resection.

RESULTS

By combining the virtual bone bank and CAOS, selection time was reduced and matching accuracy was increased. After 27.5 months of follow-up, the mean Musculoskeletal Tumor Society (MSTS) 93 functional score was 25.7 ± 1.1 points. Except for two patients with pulmonary metastases, 12 patents were alive without evidence of disease at the time this report was written.

CONCLUSIONS

The virtual bone bank system was helpful for allograft selection, tumour excision and bone reconstruction, thereby improving the safety and effectiveness of limb-salvage surgery.

Effect of Platelet-Rich Plasma on the Healing of Mandibular Defects Treated With Fresh Frozen Bone Allograft: A Radiographic Study in Dogs

The purpose of this study was to radiographically analyze the effect of autologous platelet rich plasma (PRP) on the healing of fresh frozen bone allograft (FFBA) placed in surgically created resection defects in mandibles of dogs. Bilateral resection defects measuring 1.5 cm × 1 cm were surgically created on the inferior border of the mandible in 10 adult male dogs. The defects were randomly divided into three groups: C, FFBA, and FFBA/PRP. In Group C, the defect was filled by blood clot only. In Group FFBA, the defect was filled with particulate fresh frozen bone allograft. In Group FFBA/PRP, it was filled with particulate fresh frozen bone allograft combined with PRP. At 90 days postoperative, standardized radiographs of the mandibles were obtained and results were quantitatively evaluated. Analysis of digitized radiographs indicated that non-PRP grafts were significantly less dense than the PRP grafts. Group FFBA/PRP also presented a statistically greater mineralized tissue area than Groups C and FFBA. Within the limits of this study, it can be concluded that PRP enhanced the healing of FFBA in resection defects in mandibles of dogs.

Platelet-rich preparations to improve healing. Part II: platelet activation and enrichment, leukocyte inclusion, and other selection criteria

Multiple platelet-rich preparations have been reported to improve wound and bone healing, such as platelet-rich plasma (PRP) and platelet rich fibrin (PRF). The different methods employed during their preparation are important, as they influence the quality of the product applied to a wound or surgical site. Besides the general protocol for preparing the platelet-rich product (discussed in Part 1 of this review), multiple choices need to be considered during its preparation. For example, activation of the platelets is required for the release and enmeshment of growth factors, but the method of activation may influence the resulting matrix, growth factor availability, and healing. Additionally, some methods enrich leukocytes as well as platelets, but others are designed to be leukocyte-poor. Leukocytes have many important roles in healing and their inclusion in PRP results in increased platelet concentrations. Platelet and growth factor enrichment reported for the different types of platelet-rich preparations are also compared. Generally, TGF-β1 and PDGF levels were higher in preparations that contain leukocytes compared to leukocyte-poor PRP. However, platelet concentration may be the most reliable criterion for comparing different preparations. These and other criteria are described to help guide dental and medical professionals, in large and small practices, in selecting the best procedures for their patients. The healing benefits of platelet-rich preparations along with the low risk and availability of simple preparation procedures should encourage more clinicians to incorporate platelet-rich products in their practice to accelerate healing, reduce adverse events, and improve patient outcomes.

Effect of plasma-rich in platelet-derived growth factors on peri-implant bone healing: An experimental study in canines

BACKGROUND

Tissue engineering principles can be exploited to enhance alveolar and peri-implant bone reconstruction by applying such biological factors as platelet-derived growth factors. The objective of the present study is to investigate the effect of autologous plasma-rich in growth factors (on the healing of peri-implant bone in canine mandible).

MATERIALS AND METHODS

In this prospective experimental animal study, two healthy canines of the Iranian mix breed were selected. Three months after removing their premolar teeth on both sides of the mandible, 12 implants of the Osteo Implant Corporationsystem, 5 mm in diameter and 10 mm in length, were selected to be implanted. Plasma rich in growth factors (PRGF) were applied on six implants while the other six were used as plain implants without the plasma. The implants were installed in osteotomy sites on both sides of the mandible to be removed after 4 weeks with the surrounding bones using a trephine bur. Mesio-distal sections and implant blocks, 50 μ in diameter containing the peri-implant bone, were prepared By basic fuchin toluidine-bluefor histological and histomorphometric evaluation by optical microscope. The data were analyzed using Mann-Whitney Test (P<0.05).

RESULTS

The bone trabeculae and the type of bone generation in PRGF and control groups had no statistically significant differences (P=0.261, P=0.2) although the parameters showed higher measured values in the PRGF group. However, compared to the control, application of PRGF had significantly increased bone-to-implant contact (P=0.028)

CONCLUSION

Based on the results, it may be concluded that application of PRGF on the surface of implant may enhance bone-to-implant contact.

Platelet-rich plasma in the treatment of Class II furcation defects: a histometrical study in dogs

Objective

This study was designed to evaluate the potential adjunctive benefits of platelet-rich plasma (PRP) when used with guided-tissue regeneration (GTR) and bioactive glass (BG) in the treatment of Class II furcation lesions.

Material and Methods

Bilateral Class II furcation lesions were surgically created and allowed to become chronic in the mandibular third premolars of 9 dogs. The defects were randomly assigned to: A) GTR+BG and B) GTR+BG+PRP. Similar defects were created in the maxillary third premolars and received the same treatments after 45 days. Dogs were sacrificed 90 days after the first treatment. The histometric parameters evaluated were: connective tissue adaptation, new cementum, new bone, mineralized bone area, non-mineralized bone area, and residual BG particle area.

Results

Data analysis showed a superior length of new cementum and a greater mineralized bone area for group B in both periods (p<0.05). The non-mineralized bone area was greater in the control group (p<0.05) in both periods.

Conclusion

Within the limits of this study, it can be concluded that the use of PRP in the treatment of Class II furcation defects may enhance the amount of new cementum and provide a more mineralized bone in a shorter period of time.

Evaluation of healing processes of intraosseous defects with and without guided bone regeneration and platelet rich plasma. An animal study

BACKGROUND

In most cases, the natural healing of intrabony defects only leads to restoration of tissue continuity without differentiation and function. However, repair is not regarded to be an optimal treatment method, as confirmed in many clinical cases. Thus it is important to choose a surgical procedure which makes it possible to achieve restitution ad integrum of the bone structure. The choice of the GBR technique is crucial, in terms of the clinical conditions and limitations resulting from the use of a particular material.

OBJECTIVE

The objective of this study has been the analysis of effectiveness of selected surgical treatment techniques of intrabony defects in rabbits.

MATERIALS AND METHODS

Research was conducted on 36 white rabbits. The operation technique was a criterion of division into 3 groups: BG/BOC (Bio-Oss Collagen(®)+Bio-Gide Perio(®)), BOC/PRP (Bio-Oss Collagen(®)+PRP), C (control group). Qualitative and quantitative histopathological evaluation was carried out after 1, 3, 6 and 12 months.

RESULTS

The highest value of the bone surface area 31.9% (SD 1.8) was achieved in BOC/BG group three months after the implantation, while the lowest was revealed in C - group - 12.5% (SD 1.32) one month following the procedure.

CONCLUSIONS

Upon quantitative histological assessment, the bone tissue presented the most intensive osteogenesis within one month from the application of BOC/PRP, whereas this was observed after the application of BOC/BG in later stages. The application of two regenerative methods influenced the rate, quality and overall treatment of intraosseus defects.

The role of platelet rich plasma in musculoskeletal science

The idea of using platelet rich plasma (PRP) in medicine has been around since the 1970s. It is only more recently that its use has been employed in the area of musculoskeletal science. Platelet rich plasma in this area has received much media attention being used by many celebrity sports athletes for musculoskeletal injuries. Therefore it is important for the musculoskeletal practitioner to be aware of the concepts surrounding its use and application. In this article we cover what platelet rich plasma is, how it is prepared and administered, its potential clinical application, and what the current literature discusses in the various areas of musculoskeletal science.

Effect of low-level laser therapy on incorporation of block allografts

OBJECTIVE

To assess the effect of low-level laser therapy (LLLT) on the incorporation of deep-frozen block allografts in a rabbit model.

BACKGROUND DATA

Studies have shown that LLLT has beneficial effects on tissue repair and new bone formation.

METHODS

Bone tissue was harvested from two rabbits, processed by deep-freezing and grafted into the calvaria of 12 animals, which were then randomly allocated into two groups: experimental (L) and control (C). Rabbits in group L were irradiated with an aluminum gallium arsenide diode laser (AlGaAs; wavelength 830 nm, 4 J/cm(2)), applied to four sites on the calvaria, for a total dose of 16 J/cm(2) per session. The total treatment dose after eight sessions was 128 J/cm(2). Animals were euthanized at 35 (n = 6) or 70 days (n = 6) postoperatively.

RESULTS

Deep-freeze-processed block allografts followed by LLLT showed incorporation at the graft-host interface, moderate bone remodeling, partial filling of osteocyte lacunae, less inflammatory infiltrate in the early postoperative period, and higher collagen deposition than the control group.

CONCLUSION

Optical microscopy and scanning electron microscopy showed that allograft bone processed by deep-freezing plus LLLT is suitable as an alternative for the treatment of bone defects. Use of the deep-freezing method for processing of bone grafts preserves the structural and osteoconductive characteristics of bone tissue.

Healing of fresh frozen bone allograft with or without platelet-rich plasma: a histologic and histometric study in rats

PURPOSE

This study histomorphometrically analyzed the effect of autogenous platelet-rich plasma (PRP) on healing of fresh frozen bone allograft (FFBA) in bony defects in rat calvaria.

MATERIALS AND METHODS

A 5mm-diameter defect was created in the calvarium of 30 rats. Animals were divided into three groups: C (defect was filled by blood clot only), FFBA (defect was filled with 0.01mL of FFBA), and FFBA/PRP (defect was filled with 0.01mL of FFBA combined with 100µL of PRP). All animals were euthanized at 30 days postoperatively. Histomorphometry and histology analyses were performed. Data were statistically analyzed (analysis of variance, Tukey, p<.05).

RESULTS

FFBA had a statistically smaller new bone area than groups FFBA/PRP and C. No statistically significant differences were observed between groups FFBA and FFBA/PRP with regard to remaining bone graft particle area.

CONCLUSION

It can be concluded that (1) PRP improved the incorporation of FFBA, increasing the amount of new bone formed; (2) PRP has not influenced the resorption of nonviable particles of the FFBA; and (3) presence of remaining FFBA particles might have accounted for the smaller amount of new bone observed in group FFBA when compared with control group.

Investigation of peri-implant bone healing using autologous plasma rich in growth factors in the canine mandible after 12 weeks: a pilot study

Introduction:

Faster reconstruction of patients’ masticatory systems is the aim of modern dentistry. A number of studies have indicated that application of growth factors to the surface of a dental implant leads to accelerated and enhanced osseointegration. The objective of the present study was to investigate the effect of plasma rich in growth factors on peri-implant bone healing.

Materials and Methods:

For the purpose of this study, two healthy, mixed-breed canines were selected, and the premolars were extracted from both sides of the mandible. Three months after premolar removal, 12 implants, each 5 mm in diameter and 10 mm in length, were placed in osteotomy sites on both sides of the mandible. Prior to placement, plasma rich in growth factors was applied to the surfaces of six implants, while the other six were used without plasma rich in growth factors. The implants were removed after 12 weeks along with the bone surrounding the sites using a trephine bur. One mesiodistal section containing the surrounding bone from each implant block, 50 µm in diameter, was prepared for histologic and histomorphometric investigation with an optical microscope.

Results:

The sites with implants treated with plasma rich in growth factors showed more bone-to-implant contact compared to control sites. Also, higher values for bone trabecular thickness and bone maturity were recorded for the PRGF-treated sites than for the control sites.

Conclusion:

Application of plasma rich in growth factors to the surface of an implant may enhance the bone healing process as well as bone-to-implant contact, thereby helping to achieve faster osseointegration.

Platelet autologous growth factors decrease the osteochondral regeneration capability of a collagen-hydroxyapatite scaffold in a sheep model

Background

Current research aims to develop innovative approaches to improve chondral and osteochondral regeneration. The objective of this study was to investigate the regenerative potential of platelet-rich plasma (PRP) to enhance the repair process of a collagen-hydroxyapatite scaffold in osteochondral defects in a sheep model.

Methods

PRP was added to a new, multi-layer gradient, nanocomposite scaffold that was obtained by nucleating collagen fibrils with hydroxyapatite nanoparticles. Twenty-four osteochondral lesions were created in sheep femoral condyles. The animals were randomised to three treatment groups: scaffold, scaffold loaded with autologous PRP, and empty defect (control). The animals were sacrificed and evaluated six months after surgery.

Results

Gross evaluation and histology of the specimens showed good integration of the chondral surface in both treatment groups. Significantly better bone regeneration and cartilage surface reconstruction were observed in the group treated with the scaffold alone. Incomplete bone regeneration and irregular cartilage surface integration were observed in the group treated with the scaffold where PRP was added. In the control group, no bone and cartilage defect healing occurred; defects were filled with fibrous tissue. Quantitative macroscopic and histological score evaluations confirmed the qualitative trends observed.

Conclusions

The hydroxyapatite-collagen scaffold enhanced osteochondral lesion repair, but the combination with platelet growth factors did not have an additive effect; on the contrary, PRP administration had a negative effect on the results obtained by disturbing the regenerative process. In the scaffold + PRP group, highly amorphous cartilaginous repair tissue and poorly spatially organised underlying bone tissue were found.

Comparison of mesenchymal stem cells from bone marrow and adipose tissue for bone regeneration in a critical size defect of the sheep tibia and the influence of platelet-rich plasma

Aim of the present study was to compare the osteogenic potential of bone marrow derived mesenchymal stem cells (BMSC) and adipose-tissue derived stem cells (ASC) and to evaluate the influence of platelet-rich plasma (PRP) on the osteogenic capacity of ASC in a large animal model. Ovine BMSC (BMSC-group) and ASC (ASC-group) were seeded on mineralized collagen sponges and implanted into a critical size defect of the sheep tibia (n=5 each). In an additional group, platelet-rich plasma (PRP) was used in combination with ASC (PRP-group). Unloaded mineralized collagen (EMPTY-group) served as control (n=5 each). Radiographic evaluation was performed every 2 weeks, after 26 weeks histological analysis was performed. Radiographic evaluation revealed a significantly higher amount of newly formed bone in the BMSC-group compared to the ASC-group at week 10 and compared to EMPTY-group from week 12 (all p<0.05). A superiority on radiographic level concerning bone formation of the PRP-group versus the empty control group was found (p<0.05), but not for the ASC-group. Histological analysis confirmed radiographic evaluation finding analogous significances. In conclusion, ASC seem to be inferior to BMSC in terms of their osteogenic potential but that can partially be compensated by the addition of PRP.

No effect of autologous growth factors (AGF) around ungrafted loaded implants in dogs

Autologous growth factors (AGF) is a growth-factor-rich concentrate of platelets, white blood cells and fibrinogen. Application of AGF was presumed to improve implant fixation and gap healing of non-grafted, loaded implants. We inserted one loaded titanium implant intra-articularly in each medial femoral condyle of eight dogs. Each implant was surrounded by a 0.75 mm gap. One implant in each dog was coated with AGF prior to implantation whereas the contralateral implant served as a control. AGF was prepared by isolating the buffy-coat from blood and further concentrated using an Interpore Cross UltraConcentrator. Platelet counts were increased from a median baseline of 168x10(3)/microl to 1003x10(3)/microl in AGF. However, AGF had no significant effect on implant fixation or bone formation. Even though AGF increased ultimate shear strength and energy absorption by approximately 50%, these differences had a p-value less than 0.05. The sample size in this study was small and any negative conclusions should be taken with caution due to low statistical power. We have previously demonstrated that AGF significantly improves fixation and incorporation of grafted implants. AGF might require mixing with an osteoconductive grafting material in order to provide a scaffold on which to foster bone growth and to keep the growth factors on location for a prolonged period.

Bone and wound healing augmentation with platelet-rich plasma

Over the past two decades, autologous platelets that have been sequestered, concentrated, and mixed with thrombin to generate growth factor-concentrated platelet-rich plasma for application to bone and wounds to aide healing have been a subject of great interest. This article reviews the literature related to the use of autologous platelet-rich plasma in bone and wound healing, and reviews the processes necessary to secure a high concentration of viable platelets. Although not yet definitive, autologous platelet-rich plasma has been shown to be safe, reproducible, and effective in mimicking the natural process of bone and wound healing.

Quantification of bone mass gain in response to the application of biphasic bioceramics and platelet concentrate in critical-size bone defects

Biphasic bioceramics have been widely indicated for bone reconstruction; however, the real gain in bone mass due to the presence of such biomaterials has not been established yet nor the advantages of its association with platelet concentrate. This study aims at quantifying the volume of bone matrix, osteoblasts, osteocytes, blood vessels and adipose tissue after the application of a biphasic bioceramics composed of 65% hydroxyapatite and 35% beta-tricalcium phosphate. Critical-size bone defects were produced in rabbit femora and reconstructed with bioceramics only, with bioceramics combined with platelet concentrate, with platelet concentrate alone, and with no treatment (blood clot). The quantitative evaluation was performed on histological sections using histomorphometry. Our data provide original evidence that consolidates the indication of bioceramics for clinical bone loss reconstruction. The application of biphasic bioceramics alone led to major bone mass gain and was followed by its association with platelet concentrate. On the other hand, platelet concentrate can contribute to the augmentation and maintenance of the adipose tissue, representing a new field for future applications in plastic surgery.

Interaction of platelet-rich concentrate with bone graft materials: an in vitro study

OBJECTIVE

Platelet-rich concentrate (PRC) is in routine use for orthopaedic and maxilofacial surgery and is frequently combined with bone graft materials to fill bony defects and enhance healing. Numerous studies have been performed investigating the efficacy of PRC to enhance bone healing in which a variety of graft materials have been combined with varying degrees of success. Here, we sought to determine the effect of combining PRC with different graft materials on human bone marrow stromal cell (hBMSC) proliferation, osteoblastic differentiation, and bone formation.

METHODS

Our central hypothesis is that PRC is not a true osteogenic agent but rather is osteopromotive, with cell fate determination being dependent on additional signals derived from the microenvironment. Experiments were performed with low passage (maximum 3) hBMSCs that were maintained in the presence of ascorbic acid-2-phosphate and beta-glycerol phosphate. Dexamethasone was excluded from these studies. PRC and graft materials were retained within well inserts and clotted by addition of bovine thrombin. Cell proliferation was determined by DNA content, osteoblastic commitment, and differentiation by alkaline phosphatase activity and matrix mineralization.

RESULTS

Combining PRC with the graft materials increased proliferation above that seen with the graft materials alone; however, only demineralized bone matrix (DBM) and allograft were capable of increasing proliferation above that seen with PRC alone. The increased proliferation observed in the presence of PRC coincided with decreased normalized alkaline phosphatase activity, suggesting decreased osteoblastic differentiation. However, at later time points, PRC increased mineralization compared with DBM, collagen, or beta tricalcium phosphate alone. When compared with PRC alone, addition of DBM or allograft decreased mineralization. Collagen gave rise to a small increase in mineralization, whereas beta tricalcium phosphate yielded the same level of mineralization as PRC alone.

CONCLUSIONS

The data obtained from these in vitro investigations demonstrate that the cellular responses induced by PRC and bone graft materials in hBMSC can be significantly (positively or negatively) modified by adding the agents in combination. These in vitro data highlight the need to consider the potential interaction between biologic agents when added in combination.

Platelet gel supplementation in long bone nonunions treated by external fixation

OBJECTIVE

The aim of the present study was to evaluate the use of previously frozen, thawed platelet gel supplementation to accelerate the healing of long bone nonunions treated by external fixation.

DESIGN

Prospective case series with historical controls.

SETTING

University Hospital.

PATIENTS

Twenty patients affected by tibial, humeral, or forearm atrophic nonunions were treated by percutaneous stabilization with unilateral external fixators and injection of autologous platelet gel. The healing time was compared to the result obtained in a historical control group treated without platelet gel supplementation.

MAIN OUTCOME MEASUREMENTS

Consolidation rate and radiographic healing time of nonunions in the 2 groups were assessed by independent blinded observers. The nonunion was judged to be healed when bridging callus formation on both radiographic views was observed on at least 3 of 4 cortices.

RESULTS

The healing rate of nonunion was 90% (18/20) in platelet gel cases and 85% (17/20) in controls, respectively (P = 0.633). The mean time until radiographic consolidation in nonunions supplemented with platelet gel (147 +/- 63 days) was not different to the result in the control group (153 +/- 61 days; P = 0.784). Analyzing the mean healing time for separate segments, no differences were noted between study and control group-that is, tibia: 112 +/- 43 and 130 +/- 5 days, respectively (P = 0.382); humerus, 225 +/- 36 and 202 +/- 70 days, respectively (P = 0.530).

CONCLUSION

The present study failed to show the clinical usefulness of isolated percutaneous platelet gel supplementation in long bone nonunions treated by external fixation; however, caution should be exercised in interpreting this result because the actual numbers are small and the statistical power is limited.

Orthotopic bone formation in titanium fiber mesh loaded with platelet-rich plasma and placed in segmental defects

The effect of platelet-rich plasma (PRP) on bone formation was investigated in a rabbit segmental radial defect model. The purpose of the study was to evaluate the bone inductive properties of PRP with titanium fiber mesh and autologous bone chips in a 15-mm rabbit radial defect model. Eighteen New Zealand white rabbits were divided into three groups: I, PRP with autologous bone (PRP-Ti-Bone); II, autologous bone (Ti-Bone); III, control group (Ti). The implants were placed in the radial defect for 12 weeks. After sacrifice, all specimens were harvested for histological, histomorphometrical and radiographic analysis. Histomorphometrical analysis showed that bone formation was higher in the implants with PRP (PRP-Ti-Bone: 37+/-8%) than in those without PRP (Ti-bone: 25+/-6% and Ti: 25+/-5%) after 12 weeks of implantation. It was concluded that PRP has a stimulatory effect on bone formation in titanium fiber mesh filled with autologous bone graft in segmental bone defects. Titanium fiber mesh was also shown to be an excellent scaffold material for the application of autologous bone grafts with or without PRP.

Osteogenic protein-1 increases the fixation of implants grafted with morcellised bone allograft and ProOsteon bone substitute: an experimental study in dogs

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.

Effects of platelet-rich plasma at the cellular level on healing of autologous bone-grafted mandibular defects in dogs

PURPOSE

This study describes the effect of platelet-rich plasma (PRP) at the cellular level on immediate autologous bone grafts in dog mandibles.

MATERIALS AND METHODS

Twelve adult dogs weighing 40 to 50 pounds received bilateral inferior mandibular border resections measuring 2 cm x 1 cm. The right side was grafted with milled autologous iliac corticocancellous bone along with 2 cc of PRP taken from the same animal. The left side had the same amount of milled bone placed in the defect without PRP. Three animals were sacrificed at 1, 2, 3, and 6 months postsurgery. Ten and 3 days before sacrifice, all dogs received 10 mg/kg body weight of intravenous tetracycline. At sacrifice, the grafts along with adjacent native bone were harvested and immediately fixed in Carson's fixative for 48 to 72 hours. The samples were then dehydrated over a 2-week period in a graded ethanol series and embedded in Spurr's plastic. Two 100-micron sections from the center of each graft were cut, mounted on glass slides, ground to 40 microns, and stained. A digitally generated grid was superimposed over each section, to give 32 fields of 2.5 mm2. Each of these fields was examined at a magnification of x100 to determine the number of osteoblasts and osteoclasts present.

RESULTS

The mean average of the total numbers of osteoblasts and osteoclasts were significantly higher in the PRP graft sites than in the non-PRP graft sites at 1 month. However, if specific fields were compared, then 14 of the 32 fields showed no difference in the number of osteoblasts and osteoclasts. At 2, 3, and 6 months, there was no significant difference in the total number of osteoblasts or osteoclasts in the PRP and non-PRP grafts, or in any of the 32 fields.

CONCLUSIONS

At the cellular level, PRP increased the number of osteoblasts and osteoclasts recruited to the graft site at 1 month, and this overall increase was more evident at the superior and lateral margins of the graft than in other areas. Fields along the inferior margin showed the fewest number of cells for both the PRP and non-PRP grafts. At later times there was no significant difference in the number of osteoblasts and osteoclasts in the PRP and non-PRP graft sites in any region of the grafts. This study indicates that the increased number of osteoblasts and osteoclasts in the graft sites due to the addition of PRP was short-lived, and that autologous bone grafts without PRP had similar numbers of active bone cells after 1 month in this animal model.

Use of growth factors to modify osteoinductivity of demineralized bone allografts: lessons for tissue engineering of bone

Biologically active bone graft substitute materials are needed for repair and regeneration of skeletal tissues. Current approaches are focused on the use of osteoinductive agents, including bone morphogenetic proteins (BMP) in combination with biodegradable carriers. Demineralized freeze-dried bone allograft (DFDBA) can provide an osteoconductive surface and, at the same time, function as a time-release carrier for BMP. Donor variability, however, limits the predictability of DFDBA as an osteoinductive material. This article examines the use of growth factors, including platelet-rich plasma, platelet-derived growth factor, enamel matrix derivatives, and BMP-2, to enhance the osteoinductive properties of human DFDBA.

The effects of local platelet rich plasma delivery on diabetic fracture healing

Several studies have documented that diabetes impairs bone healing clinically and experimentally. The percutaneous delivery of platelet rich plasma (PRP) was used in the diabetic BB Wistar femur fracture model to investigate the use of PRP as a concentrated source of critical early growth factors on bone healing. PRP delivery at the fracture site normalized the early (cellular proliferation and chondrogenesis) parameters while improving the late (mechanical strength) parameters of diabetic fracture healing. These results suggest a role for PRP in mediating diabetic fracture healing and potentially other high risk fractures.

Platelet-rich fibrin (PRF): a second-generation platelet concentrate. Part V: histologic evaluations of PRF effects on bone allograft maturation in sinus lift

OBJECTIVE

Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. The use of platelet gel to improve bone regeneration is a recent technique in implantology. However, the biologic properties and real effects of such products remain controversial. In this article, we therefore attempt to evaluate the potential of PRF in combination with freeze-dried bone allograft (FDBA) (Phoenix; TBF, France) to enhance bone regeneration in sinus floor elevation.

STUDY DESIGN

Nine sinus floor augmentations were performed. In 6 sites, PRF was added to FDBA particles (test group), and in 3 sites FDBA without PRF was used (control group). Four months later for the test group and 8 months later for the control group, bone specimens were harvested from the augmented region during the implant insertion procedure. These specimens were treated for histologic analysis.

RESULTS

Histologic evaluations reveal the presence of residual bone surrounded by newly formed bone and connective tissue. After 4 months of healing time, histologic maturation of the test group appears to be identical to that of the control group after a period of 8 months. Moreover, the quantities of newly formed bone were equivalent between the 2 protocols.

CONCLUSIONS

Sinus floor augmentation with FDBA and PRF leads to a reduction of healing time prior to implant placement. From a histologic point of view, this healing time could be reduced to 4 months, but large-scale studies are still necessary to validate these first results.

Platelet-rich fibrin (PRF): a second-generation platelet concentrate. Part I: technological concepts and evolution

Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates geared to simplified preparation without biochemical blood handling. In this initial article, we describe the conceptual and technical evolution from fibrin glues to platelet concentrates. This retrospective analysis is necessary for the understanding of fibrin technologies and the evaluation of the biochemical properties of 3 generations of surgical additives, respectively fibrin adhesives, concentrated platelet-rich plasma (cPRP) and PRF. Indeed, the 3-dimensional fibrin architecture is deeply dependent on artificial clinical polymerization processes, such as massive bovine thrombin addition. Currently, the slow polymerization during PRF preparation seems to generate a fibrin network very similar to the natural one. Such a network leads to a more efficient cell migration and proliferation and thus cicatrization.

The role of platelet-rich plasma in foot and ankle surgery

Platelet-rich plasma (PRP), derived from autologous blood, is defined as a volume of plasma that has a platelet concentration that typically is five times greater (approximately 1,000,000/microl) than physiologic levels. PRP serves as a reservoir of critical growth factors, including platelet-derived growth factor, transforming growth factor-beta, and insulin-like growth factor-I. Although there is an abundance of literature pertaining to dental applications, this article highlights the use of PRP in orthopedic applications, ranging from PRP preparation to in vitro and in vivo studies to clinical research.