Aims. Trained immunity confers non-specific protection against various types of infectious diseases, including bone and joint infection. Platelets are active participants in the immune response to pathogens and foreign substances, but their role in trained immunity remains elusive. Methods. We first trained the innate immune system of C57BL/6 mice via intravenous injection of two toll-like receptor agonists (zymosan and lipopolysaccharide). Two, four, and eight weeks later, we isolated platelets from immunity-trained and control mice, and then assessed whether immunity training altered platelet releasate. To better understand the role of immunity-trained platelets in bone and joint infection development, we transfused platelets from immunity-trained mice into naïve mice, and then challenged the recipient mice with Staphylococcus aureus or Escherichia coli. Results. After immunity training, the levels of pro-inflammatory cytokines (tumour necrosis factor alpha (TNF-α), interleukin (IL)-17A) and chemokines (CCL5, CXCL4, CXCL5, CXCL7, CXCL12) increased significantly in platelet releasate, while the levels of anti-inflammatory cytokines (IL-4, IL-13) decreased. Other platelet-secreted factors (e.g. platelet-derived growth factor (PDGF)-AA, PDGF-AB, PDGF-BB, cathepsin D, serotonin, and histamine) were statistically indistinguishable between the two groups. Transfusion of platelets from trained mice into naïve mice reduced infection risk and bacterial burden after local or systemic challenge with either S. aureus or E. coli. Conclusion. Immunity training altered platelet releasate by increasing the levels of inflammatory cytokines/chemokines and decreasing the levels of anti-inflammatory cytokines. Transfusion of platelets from immunity-trained mice conferred protection against bone and joint infection, suggesting that alteration of platelet releasate might be an important mechanism underlying trained immunity and may have clinical implications. Cite this article: Bone Joint Res 2022;11(2):73–81

Aim. The diagnosis of septic arthritis mostly relies on clinical examination, several blood parameters including white blood cell count, C-reactive protein, sedimentation, and the analysis of the joint aspiration. However, the diagnosis can be difficult when the symptoms are vague and the information obtained from laboratory might be insufficient for definitive diagnosis. This study aimed to evaluate several ratios obtained from routine blood tests for a possible use in the diagnosis of septic arthritis. Method. The adult patients who were operated in our clinic due to septic arthritis between 2014–2020 were identified and retrospectively evaluated. The patients with any blood disorders or missing file information were excluded. A total of 36 patients were found to be eligible for inclusion. The control group included 40 patients without any sign of infection who underwent total knee arthroplasty due to knee osteoarthritis. Preoperative blood tests of each patients were examined. In addition to CRP and sedimentation values, neutrophil-lymphocyte, monocyte-lymphocyte, platelet-lymphocyte, and platelet count-mean platelet volume were calculated and receiving operating characteristics (ROC) curve analysis was made to determine the sensitivity, specificity and area under curve (AUC) values of these parameters. Results. The distribution of affected joint in septic arthritis group was as follow; 22 knees, 6 hips, 4 shoulders, 2 elbows, 1 wrist and 1 ankle. The cultures of joint aspiration yielded positive result in 19 patients while the cultures were negative in 17 patients. All of the analyzed parameters were significantly different between the groups (p<0.001). ROC curve analysis results are given in detail, in Table 1 and Figure 1. The AUC value was 97.3 when only CRP and sedimentation values were used but increased to 98.6 when neutrophile/ lymphocyte ratio was added and increased to 100 when all analyzed parameters were included. Conclusions. The analyzed parameters were found to increase the overall sensitivity and specificity when used together with acute phase reactants. However, when evaluated separately, CRP and sedimentation were still found as the most valuable parameters in the diagnosis of septic arthritis. In the diagnosis of septic arthritis, 35 mm/hr cut-off value for sedimentation and 10 mg/L cut-off value for CRP were found more sensitive and specific compared to standard laboratory cut-off values of 20 mm/hr and 5 mg/L. For any tables or figures, please contact the authors directly

Objective. Despite the current revolution in molecular medicine that has benefitted the treatment of certain diseases (Ross 2002), idiopathic scoliosis has resisted attempts to understand the molecular basis of its curve development. Lowe et al (2002) in a longitudinal study of 55 AIS patients concluded that platelet calmodulin levels correlate closely with curve progression and stabilization by bracing or spine fusion. They suggest that the platelet is a “minimuscle” with a protein contractile system (actin and myosin) similar to that of skeletal muscle. Using Lowe’s data we found that percentage platelet calmodulin change correlates significantly with percentage Cobb angle change (ANOVA, p=0.0003, n=54) that led us to suggest a platelet/skeletal hypothesis to account for their findings as part of a cascade concept for the pathogenesis of AIS. Hypothesis. The human immature vertebral body is unusual among mammals in lacking epiphyses. This may explain why an axial load transmitted directly from the intervertebral disc deforms mature vertebral body end-plates as an axial inward bulge (Brinckmann et al 1983). In immature normal vertebral bodies vascular “lakes” (resembling bunches of grapes) have been found adjacent to the disc growth plates in subjects aged 9 to 13 years of age (Mineiro 1965). These “lakes” may provide a susceptibility to platelet activation from vascular stasis and shear stresses. In addition to their role in hemostasis platelets contain many growth factors including TGF-βs in α-granules that are secreted at a fracture site (Bolander 1992). TGF-βs are found in human neonatal rib growth plates (Horner et al 1998) but, like estrogen receptors, have not yet been sought in human intervertebral disc growth plates. We hypothesize that in the presence of a small scoliosis curve (from unknown causes ?spine, rib, muscle, or nervous system) platelets, as they circulate through vessels in eccentrically-loaded and deforming immature vertebral bodies particularly about the curve apex in the presence of a basic defect, are activated also by repeated axial inward bulges of disc growth plates causing mechanical micro-insults with endothelial cell desquamation and the formation of a calcium-cadmodulin complex. The latter is associated with platelet contraction (shape change) and the secretion from α-granules of various growth factors including angiogenic regulators (platelet release reaction, Hartwig 2003, Reed 2002, Rendu and Brohard-Bohn 2002). These growth factors abet the hormone-driven growth of the already mechanically-compromised disc growth plates and induce anterior spinal overgrowth and curve progression. The basic defect in AIS could be 1) a platelet, endothelial, or subendothelial anomaly, defect, or functional (?hormonal) disorder, and 2) one or more genetic polymorphisms that involve platelet receptors (Afshar-Kharghan and Bray 2002) and putative estrogen receptors in vertebral disc growth plates (Inoue et al 2002ab). The predilection of progressive AIS for girls may be related to the cyclical platelet functions in women associated with normal uterine function (Jones et al 1983, Pansini et al 1986, Tarantino et al 1994, Faraday et 1997). Curve laterality is determined by factors that initiate curve progression. Low plasma melatonin of progressive AIS may act both by a reduced antagonism to calmodulin (Lowe 2000, Dubousset and Machida 2001) and facilitating platelet aggregation with secretion of growth factors from α-granules. Conclusions. The platelet/skeletal hypothesis for progressive AIS and the cascade concept suggests much new research. The hypothesis has genetic, diagnostic, prognostic and potential therapeutic implications. It raises questions about the possibility of changes in platelet calmodulin levels in other progressive and resolving deformities that occur in the immature and adult skeleton

Platelet-rich plasma (PRP) has been demonstrated to benefit a variety of disciplines. But there exists heterogeneity in results obtained due to lack of standardization of the preparation protocols employed in them. We aim to identify and standardize a preparation protocol for PRP with maximum recovery of platelets to obtain reproducible results across studies. Blood samples were collected from 20 healthy volunteers. The double spin protocol of PRP preparation was analyzed for variables such as centrifugal acceleration, time, and volume of blood processed and final product utilized. The final PRP prepared was investigated for platelet recovery, concentration, integrity, and viability. We noted maximum platelet recovery (86-99%) with a mean concentration factor of 6-times baseline, with double centrifugation protocol at 100xg and 1600xg for 20 minutes each. We also noted that 10 ml of blood in a 15 ml tube was the ideal volume of blood to be processed to maximize platelet recovery. We demonstrated that the lower 1/3rd is the ideal volume to be utilized for clinical application. We did not note a loss of integrity or viability of the platelets in the final product from the above-said protocol. Preparation of PRP by the double spin protocol of 10 ml of blood at 100xg and 1600xg for 20 minutes each in a 15ml tube and using the lower 1/3rd of the final product demonstrated consistent high platelet recovery (86-99%) and concentration (6x) without disturbing the platelet integrity or viability

Degenerative disc disease, associated to low back pain, afflicts more than 50% of humans, and represents a major healthcare problem, especially for the pathology initiation. Current treatments range from conservative strategies to more invasive surgical techniques, such as disc removal and vertebral fusion. In the Intervertebral Disease (IVD) the nucleus pulposus (NP) degeneration is a key factor for the pathology initiation. Several tissue engineering approaches aiming to restore the appropriate NP cell (NPCs) and matrix content, were attempted by using adult stromal cells either from bone marrow or adipose tissue, chondrocytes, notochordal cells and more recently also pluripotent stem cells. However, none was fully satisfactory since the NP acid and a-vascularized environment appeared averse to the implanted heterologous cells. Several studies demonstrated the efficacy of platelet derivatives such as platelet rich plasma (PRP) in promoting the regeneration of connective tissues. We investigated the efficacy of PRP on NPCs proliferation and differentiation with the goal to propose the direct stimulation of resident cells (stimulation of endogenous cells – less invasive surgical procedure) or the implantation of NPCs expanded in vitro in the presence of PRP as therapeutic agents in IVD degeneration. NPCs were isolated from small fragments of NP explants, cultivated in medium supplemented with PRP or FCS (standard condition control) and characterized by FACS analysis for the expression of the typical mesenchymal stem cells markers CD34, CD44, CD45, CD73, CD90 and CD105. NPCs cultured in PL showed a phenotypic profile like the cells cultured in FCS. However, compared to NPCs expanded in the presence of FCS, NPCs expanded in PRP showed a much better proliferation and differentiation capacity. NPCs differentiation was evaluated by the cell ability to produce an organized metachromatic cartilaginous matrix, confirmed by the positive immunohistochemical staining for chondrogenic markers

Objectives. Mesenchymal stem cells have the ability to differentiate into various cell types, and thus have emerged as promising alternatives to chondrocytes in cell-based cartilage repair methods. The aim of this experimental study was to investigate the effect of bone marrow derived mesenchymal stem cells combined with platelet rich fibrin on osteochondral defect repair and articular cartilage regeneration in a canine model. Methods. Osteochondral defects were created on the medial femoral condyles of 12 adult male mixed breed dogs. They were either treated with stem cells seeded on platelet rich fibrin or left empty. Macroscopic and histological evaluation of the repair tissue was conducted after four, 16 and 24 weeks using the International Cartilage Repair Society macroscopic and the O’Driscoll histological grading systems. Results were reported as mean and standard deviation (. sd. ) and compared at different time points between the two groups using the Mann-Whitney U test, with a value < 0.05 considered statistically significant. Results. Higher cumulative macroscopic and histological scores were observed in stem cell treated defects throughout the study period with significant differences noted at four and 24 weeks (9.25, . sd. 0.5 vs 7.25, . sd. 0.95, and 10, . sd. 0.81 vs 7.5, . sd. 0.57; p < 0.05) and 16 weeks (16.5, . sd. 4.04 vs 11, . sd. 1.15; p < 0.05), respectively. Superior gross and histological characteristics were also observed in stem cell treated defects. Conclusion. The use of autologous culture expanded bone marrow derived mesenchymal stem cells on platelet rich fibrin is a novel method for articular cartilage regeneration. It is postulated that platelet rich fibrin creates a suitable environment for proliferation and differentiation of stem cells by releasing endogenous growth factors resulting in creation of a hyaline-like reparative tissue. Cite this article: D. Kazemi, K. Shams Asenjan, N. Dehdilani, H. Parsa. Canine articular cartilage regeneration using mesenchymal stem cells seeded on platelet rich fibrin: Macroscopic and histological assessments. Bone Joint Res 2017;6:98–107. DOI: 10.1302/2046-3758.62.BJR-2016-0188.R1

The aim of our study was to investigate the effect of platelet-rich plasma on the proliferation and differentiation of rat bone-marrow cells and to determine an optimal platelet concentration in plasma for osseous tissue engineering. Rat bone-marrow cells embedded in different concentrations of platelet-rich plasma gel were cultured for six days. Their potential for proliferation and osteogenic differentiation was analysed. Using a rat limb-lengthening model, the cultured rat bone-marrow cells with platelet-rich plasma of variable concentrations were transplanted into the distraction gap and the quality of the regenerate bone was evaluated radiologically. Cellular proliferation was enhanced in all the platelet-rich plasma groups in a dose-dependent manner. Although no significant differences in the production and mRNA expression of alkaline phosphatase were detected among these groups, mature bone regenerates were more prevalent in the group with the highest concentration of platelets. Our results indicate that a high platelet concentration in the platelet-rich plasma in combination with osteoblastic cells could accelerate the formation of new bone during limb-lengthening procedures

Objectives. Platelet-rich plasma (PRP) is being used increasingly often in the clinical setting to treat tendon-related pathologies. Yet the optimal PRP preparations to promote tendon healing in different patient populations are poorly defined. Here, we sought to determine whether increasing the concentration of platelet-derived proteins within a derivative of PRP, platelet lysate (PL), enhances tenocyte proliferation and migration in vitro, and whether the mitogenic properties of PL change with donor age. Methods. Concentrated PLs from both young (< 50 years) and aged (> 50 years) donors were prepared by exposing pooled PRP to a series of freeze-thaw cycles followed by dilution in plasma, and the levels of several platelet-derived proteins were measured using multiplex immunoassay technology. Human tenocytes were cultured with PLs to simulate a clinically relevant PRP treatment range, and cell growth and migration were assessed using DNA quantitation and gap closure assays, respectively. Results. Platelet-derived protein levels increased alongside higher PL concentrations, and PLs from both age groups improved tenocyte proliferation relative to control conditions. However, PLs from aged donors yielded a dose-response relationship in tenocyte behaviour, with higher PL concentrations resulting in increased tenocyte proliferation and migration. Conversely, no significant differences in tenocyte behaviour were detected when increasing the concentration of PLs from younger donors. Conclusion. Higher PL concentrations, when prepared from the PRP of aged but not young donors, were more effective than lower PL concentrations at promoting tenocyte proliferation and migration in vitro. Cite this article: D. R. Berger, C. J. Centeno, N. J. Steinmetz. Platelet lysates from aged donors promote human tenocyte proliferation and migration in a concentration-dependent manner. Bone Joint Res 2019;8:32–40. DOI: 10.1302/2046-3758.81.BJR-2018-0164.R1

This study was undertaken to assess the contribution of pulmonary fat embolism to systemic platelet activation in a rabbit model of fat embolism. Fifteen NZW rabbits were randomly assigned into one of two groups: fat embolism and control. Fat embolism was induced via intramedullary canal pressurization with a 1–1.5 ml bone cement injection. Only the animals that underwent fat embolism displayed consistent platelet activation, as demonstrated by platelet degranulation and procoagulatory surface expression. These findings suggest that fat embolism plays a role in platelet activation and in the overall activation of hemostasis following trauma. The objective of this study was to use a recently developed rabbit model of fat embolism to assess the systemic hemostatic response to pulmonary fat embolism. Our findings demonstrate platelet activation following forced liberation of bone marrow contents into the circulation only in the FE group, as demonstrated by CD62P elevation (a marker of platelet degranulation) and annexin V elevation (a marker of procoagulatory surface expression). Platelet activation also coincided with significantly lower platelet counts in the FE group at two and four hours post embolism, suggesting platelet aggregation. These findings suggest that fat embolism plays a role in platelet activation and in the overall activation of hemostasis following trauma. Platelet count decreased significantly at two and four hours post knee manipulation only in the FE group. Annexin V expression increased significantly in the FE group at two and four hours post knee manipulation. Lastly, CD62P expression only increased significantly in the FE group at two hours post knee manipulation. Fifteen New Zealand White male rabbits were randomly assigned into one of two groups: control and fat embolism (FE). In FE group (n=8), the intramedullary cavity was drilled, reamed and pressurized with a 1–1.5 ml bone cement injection. In the control group (n=7), a sham knee incision was made, exposing both femoral condyles, but was immediately closed without further manipulations. All animals were mechanically ventilated for an additional monitoring period of four hours post-surgical closure. For flow cytometric evaluation of platelet activation, blood samples were stained with fluorescence-conjugated antibodies against CD41 (FITC), CD62P (P-selectin) and annexin V (FITC). Platelet events were identified by their characteristic CD41 staining and size and were analyzed using a flow cytometer. All animals were mechanically ventilated for four hours post surgical closure. The implications of platelet activation following fat embolism are numerous, ranging from adherence and aggregation, to secretion of key components of both the coagulation and inflammatory cascades

Background. Processing of allografts, which are used to fill bone defects in orthopaedic surgery, includes chemical cleaning as well as gamma irradiation to reduce the risk of infection. Viable bone cells are destroyed and denaturing proteins present in the graft the osteoconductive and osteoinductive characteristics of allografts are altered. The aim of the study was to investigate the mechanical differences of chemical cleaned allografts by adding blood, clotted blood, platelet concentrate and platelet gel using a uniaxial compression test. Methods. The allografts were chemically cleaned, dried and standardized according to their grain size distribution. In group BL 4 ml blood, in CB 4 ml blood and 480 μl of 1 mol calcium chloride to achieve clotting, in PC 4 ml of concentrated platelet gel, in PG 4 ml of concentrated platelets and 666 μl of 1 mol calcium chloride were added. Uniaxial compression test was carried out for the four groups before and after compating the allografts. Results. No statistically significant decrease of the initial density was observed after compaction for BL and PC. In CB a statistical significant decrease of the initial density by 10% was observed, while PG decreased its initial density after compaction by 13%. Considering the density at the yield limit before and after compaction BL showed a statistically significant decrease of 13% and PG of 14%. In CB and PC no statistically significant decrease of the density at the yield limit could be observed. All groups showed a statistical significant difference when comparing the yield limit before and after compaction. BL and PC showed a ∼35% higher yield limit after compaction, while in the groups with the activation liquid CB and PG the yield limit increased by 15% for CB and 20% for PG. No statistically significant difference between groups was found for the density at the yield limit before compaction (p=0.157), for the initial density (p=0.523), the density at the yield limit (p=0.681) and the yield limit itself (p=0.423) after compaction. A statistically significant difference between the groups under investigation was found for the initial density before compaction (p=0.041) and for the yield limit before compaction (p=0.041). BL had a statistically significant lower initial density than PG (p=0.048). All other pairwise comparisons between groups did not reach statistically significance for the initial density before compaction. Conclusion. Adding blood, PRP or PC in allografts has shown in different studies to enhance bone ingrowth. The authors recommend to chemical clean allografts for large defects, optimize their grain size distribution and add platelet concentrate or platelet rich plasma for enhancing as well primary stability as well bone ingrowth. The recommended processing procedure has to be tested in an in-vivo study

We present seven patients with recurrent haemarthroses after total knee arthroplasty, caused by an inherent platelet function defect. These patients developed painful knee swelling, persistent bleeding and/or wound breakdown, a platelet factor 3 availability defect being identified in all cases. Surgical exploration, with joint debridement, lavage and synovectomy, was performed in four patients who did not improve with conservative therapy. Histopathological examination of synovium revealed a focal synovial reaction with histiocytic infiltration, and occasional foreign-body giant cells. One patient required an early revision because of aseptic loosening of their tibial component. The condition was treated by single-donor platelet transfusions with good results. The diagnosis, management, and relevance of this disorder are discussed

Introduction: The short-term functional recovery after a total knee arthroplasty (TKA) is largely dependent on initial wound healing. Haematoma formation may lead to prolonged wound drainage and tissue necrosis, which can have a negative effect on early range of motion, post-operative pain and infection rate. To decrease haematoma formation, primary soft tissue homeostasis and adequate tissue repair are essential. Growth factors, especially PDGF (platelet derived growth factor) and TGF-β (transforming growth factor-beta), play a crucial role in the biochemical cascade at the site of repair. These growth factors are mostly derived from platelets. The objective of this study was to evaluate the effect of autologous platelet concentrate on blood loss (postoperative decrease of haemoglobin concentration), wound healing complications, range of motion, pain reduction and outcome scores when used in total knee arthroplasty. Method: 96 patients undergoing primary total knee arthroplasty were included and randomized in two groups. In the study group, autologous platelet concentrate was applied at wound closure. Treatment with autologous platelet concentrate involves direct application of concentrated platelets, growth factors and fibrin in the operation wound. A small volume (55–110 ml) of the patient’s own blood is taken to derive a platelet rich gel which can be sprayed directly into the wound. The peri-operative haemoglobin concentration, peri-operative range of motion, haematoma formation, number of days of wound drainage and complications were collected. The pain score (VAS), IKSS, 12 questionaire score and SF-36 score were recorded at regular intervals. Results: There was no significant difference between the groups in post-operative haemoglobin decrease, range of motion, haematoma formation, wound drainage or pain scores. In the study group there were 3 deep infections. In the control group we had no infections. Conclusion: We found no benefit in the use of autologous platelet concentrate in total knee arthroplasty. Furthermore, it is of concern that we had three deep infections with use of the autologous platelet concentrate

Today there is a great interest in the use of the autol-ogous platelet growth factors (APGF) in the field of orthopaedic surgery. The platelets are like a cellular laboratory and secrete, store, and leave many growth factors. These APGF are able to increase the reproduction of futtock, mesenchymal, fibroblast, osteoblast, and endothelial cells, which have a homothetic effect on macrophages and mono- and polymorphonuclear cells. Between 2001 and 2003 about 60 patients were treated with APGF in the form of gel. It was used for osteosynthesis of high energy fractures with soft tissue and bone loss, in arthrodesis of scoliotic spine, and in the emergency treatment of hand trauma. The platelet gel was used for 4 weeks. The average time for recovery was about 1 month for the soft tissue lesions. The use of APGF enables a speedy recovery and quick resumption of work. The healing time of the fractures decreases by 50% and the fingertip lesions with exposed bone can be treated with APGF without shortening or plastic surgery being necessary. It is possible to use platelet gel for replacement of soft tissue, for osteosynthesis of fractures, and to fill up defect cavities. Thus, this opens new perspectives for treatment in orthopaedic surgery. The patients could return to normal daily activity in a short time and it is possible to reach good results, offering a better quality of life

The incorporation of platelet rich plasma (PRP) in the treatment of various musculoskeletal conditions has increased exponentially over the past decade. While described most often as an augment or treatment for tendinopathies and acute tendon injuries, more recently, PRP has been described as an adjunct to arthroplasty procedures, mostly with respect to knee arthroplasty. In the shoulder, only a single study has been published, in which Zavadil and colleagues performed a randomised study of 40 patients undergoing total shoulder arthroplasty undergoing either treatment with autologous platelet gel and platelet poor plasma (n=20) or undergoing no biologic treatment (control group, n=20). The authors noted that the treatment group had significantly lower pain scores, less pain medication requirements, and improved internal rotation when compared to controls; in addition, there were no significant differences in post-operative (compared to pre-operative) hemoglobin levels or length of stay. The vast majority of arthroplasty studies discussing PRP analyze the impact of treatment on wound healing, post-operative pain, post-operative range of motion, and need for post-operative blood transfusions. Unfortunately, due to the substantial variability of methodology (not all PRP preparations are the same) in the available studies as well as the variability in outcomes reporting, direct comparison between different studies is not feasible. Here, we discuss the basic science elements of PRP relevant to arthroplasty, the variability of PRP solutions, the specific applications of PRP in arthroplasty, and the latest clinical outcomes analyses of patients undergoing PRP therapy in conjunction with shoulder arthroplasty

Introduction: As Achilles tendon ruptures are healing slowly, many attempts are made trying to improve the healing after injury. Rat experiments have shown that injection of platelets improves tendon healing. A clinical study on patients has also shown a better outcome after injecting platelets into the rupture area. Therefore we wanted to verify the effect of platelets by measuring the mechanical properties of the healing Achilles tendon in a randomised study. Methods: We included 30 patients with an Achilles tendon rupture. All patients left one blood unit at the hospital blood bank. From this unit of blood approximately 20 ml of platelet concentrate were gained. All patients were operated the next day using an open technique. Just before wound closure, patients were randomised into 2 groups, with one group receiving 10 ml of their own platelet concentrate. In order to measure mechanical properties, we implanted Tantalum beads on either side of the rupture giving us the chance of exactly determining the distance between the beads using RSA and thereby measuring the stiffness of the tendon. CT was used to measure the area of the rupture site. Both groups were postoperatively treated with a cast for 7 weeks. 4 weeks with the ankle in the equines position and 3 weeks in the neutral position. After cast removal, the patients started rehabilitation. The patients in both groups received exactly the same treatment after surgery. Patients were examined with CT and RSA to determine area, stiffness and modulus of elasticity. Measurements were performed at 7 weeks after operation and again at 19 weeks. Results: 16 patients were randomised to platelet concentrate. One patient got a deep infection and another patient suffered from a rerupture of the Achilles tendon. Both patients had to be excluded after the first CT- and RSA-examination. Both patients had received platelet concentrate. There was no significant difference between both groups after 7 and 19 weeks in area, stiffness or modulus of elasticity. Discussion: Our results indicate that platelet concentrate does not improve the mechanical properties of the healing Achilles tendon, at least when patients are treated with a cast for 7 weeks. Studies have shown that the effect of platelet concentrate is depending on a certain loading of the Achilles tendon during the early phase of healing. Unfortunately we do not know much about loading of the Achilles tendon while having the leg in a cast, but the rigid fixation might lead to certain unloading. Further studies are needed to learn more about loading of the Achilles tendon in a cast. Furthermore we have also done a clinical examination of all patients, as we know from a previous study that there is a correlation between early mechanical properties and clinical outcome but we have not evaluated the clinical results of this study yet

Introduction and Objectives: Growth factors with osteoinductive capacity can be considered biomaterials with significant activity in repair and regeneration processes in live beings. We carried out a study of an isolated application of a component rich in platelets and growth factors, platelet rich plasma (PRP), in a bone defect,. Materials and Methods: We carried out an experimental controlled prospective bilaterally comparative study in 30 New Zealand rabbits, with 6 mm diameter defects in the proximal metaphysis of the tibia and diaphysis of the fibula. The animals were divided into 2 groups of 15 individuals that received platelet rich plasma (PRP) or plasma poor in platelets (ppp) in their right tibia and fibula. The left tibia and fibula were used as non-treated controls. X-rays, CT scans and histological studies were assessed at 8, 12 and 16 weeks. Results: The CT scans, bone mineral density and histological studies showed improvement in the group treated with plasma poor in platelets (ppp) without any significant differences. Repair processes took place through membranous ossification. On statistical assessment, no significant statistical difference between variables was found. Discussion and Conclusions: In our experimental study of bone defects in experimental animals we did not find that platelet rich plasma, substance or autologous compound, had any osteoinductive or osteopromoting capacity

Introduction: External fixation has evolved from a mean to hold a bone in position to one that allows a gradual correction and lengthening. Platelet gel has been reported to be effective in enhancing osteogenesis. The association of these techniques could be effective in the treatment of pottraumatic bone loss fracture. Materials and methods: Platelet gel has been obtained mixing 50 mL of autologous platelet concentrate to 2.5 mL of fibrin glue, produced from autologous FFP through CS-1 Cryoseal Thermogenesis. Patient 1: Male, 39 years old, smoker, bearing tibial non-union with 17 cm bone loss has been treated by trifocal technique with platelet gel in the docking site procedure with autologous bone graft. Patient 2: Male, 43 years old, smoker, suffering from exposed femoral fracture with sovracondilar bone loss, treated by acute shortening and proximal osteotomy in order to improve distractional ostogenesis according to Ilizarov method. Platelet gel had been positioned in the non-union sovracondilar site. Results. Patient 1 has reached a good bone repair in the platelet gel application site within 4 months. Patient 2 has healed within 3 months

Purpose. The recent emergence of autologous blood concentrates, such as platelet rich plasma (PRP), as a treatment option for patients with orthopaedic injuries has led to an extensive debate about their clinical benefit. Our objective was to determine the effectiveness of autologous blood concentrates compared with control therapy in improving pain in patients with orthopaedic bone and soft tissue injuries. Method. We conducted a systematic review of MEDLINE and EMBASE from 1996 and 1947, respectively, up to July 2010. Additional studies were identified by contacting experts, searching the bibliographies of the included studies as well as orthopaedic meeting archives. We included published and unpublished randomized controlled trials or prospective cohort studies that compared autologous blood concentrates with a control therapy in patients with an orthopaedic injury. Two reviewers, working in duplicate, abstracted data on study characteristics and protocol. Reviewers resolved disagreement by consensus. Results. We identified 18 randomized trials and nine prospective cohort studies. There was a lack of consistency in outcome measures across all studies. Four randomized controlled trials (N=275) and three prospective cohort studies (N=88) reported visual analog scale (VAS) scores when comparing platelet rich plasma with a control therapy across injuries to the acromion, lateral epicondyle, anterior cruciate ligament, patella, tibia and spine. There was no significant benefit for platelet rich plasma up to and including six months across randomized trial (standardized mean difference −0.35; 95% confidence interval, −0.98 to 0.28) or prospective cohort data (standardized mean difference −0.20; 95% confidence interval, −0.64 to 0.23). Conclusion. There is a lack of evidence to support the efficacy of platelet rich plasma and autologous blood concentrates as a treatment modality for orthopaedic bone and soft tissue injuries. The literature is further complicated by a lack of standardization in study protocols, platelet separation techniques, and outcome measures

Introduction. Platelets play a central role in haemostasis and wound healing. We have used autologous Platelet Rich Plasma (PRP) to stimulate healing in a variety of cases. We would like to present our early experience with this technique. Method. PRP is produced by centrifuging a sample of the patient’s blood. The volume of PRP produced is about 10% of the original volume. Thrombin, derived from the patient’s plasma, is mixed with the PRP to produce a platelet gel. This gel is semi-solid and makes the PRP more manageable intra-operatively. It can be used on its own, mixed with bone graft or de-mineralised bone matrix (DBM.). Results. We have used platelet gel in 14 cases for a variety of clinical conditions. 57% were males and the mean age was 44.1 (range: 7–77.) Cases included 3 elective joint fusions, 7 non unions, 2 case of chronic osteomyelitis, 1 acute fracture and 1 pathological fracture. The gel was mixed with autologous bone graft in 10 cases, DBM in 1 case and used on its own in 3 cases. The number of cases is too small to make any comment on the rate of bone union. Some practical issues have arisen during the use of platelet gel. Discussion. Is it better to give a large number of growth factors at slightly above background levels or a single growth factor millions of times above background level? This paper doesn’t answer that question but because wound and bone healing relies upon a cascade of growth factors, it is attractive to be able to provide many of these factors. Further studies are required to answer this fundamental question

Introduction: It is well known that the fate of biomaterials is determined by the distribution of proteins attached to the surface from the initial contact with blood or serum. This profile determines wether a material is inert, creates a foreign body response or is bioactive. Bioinert materials, such as polyethylene completely denature surface proteins, whilst materials inducing inflammatory responses are predisposed to complement protein attachment. Bioactive materials such autologous tissue grafts adsorb, but do not denature serum proteins such as fibronectin and Von Willebrand’s factor. This does not interfere with the healing cascade. This aim of this study is to prepare a synthetic bone graft substitute that activates the body’s autologous healing cascade by activating platelets, without activating a complement response through the controlled adsorption of serum proteins. Methods: Polymers composed of varied concentration of acrylic acid (AA) and comonomers (methyl, ethyl and butyl methacrylates (MMA, EMA, BMA)) were prepared in glass vials by free radical polymerisation. Fresh blood was collected from a healthy donor and pipetted immediately into each chamber. Glass was used as a control. The chambers were incubated at 37o C for 2 hours. The surface morphology was examined using Scanning Electron Microscopy (SEM). Concentration of complement protein C5a and prothrombin fragments 1 and 2 were determined using commercial ELISA kits. Foreign body reaction (FBR) initiated by the biomaterial was estimated by counting leukocytes on clot sections using immunofluorescence. Results: Extent of coagulation was correlated with plasma concentrations of Prothrombin fragments 1 and 2. These measurements show blood incubated with various polymers composed of different comonomers all promoted the formation of blood clots. It was found that the leukocyte population towards the interface of clot and polymer (AA:MMA) decreased with increasing surface acid concentration (65%AA:MMA 30 leukocytes/0.25mm2, glass 70 leukocytes/0.25mm2 (p< 0.05)). FBR is induced by the activation of complement system. The percentage of C5a concentration detected in blood incubated with various polymers composed of different comonomers relative to normal serum level of C5a (35ng/mL). No significant elevations of C5a were measured from polymer 65% AA:MMA and 65% AA:EMA. Glass induced vigorous complement response as expected. The synergistic combination of surface acid concentration and comonomers had a significant effect on extent of FBR. Increased acid concentration resulted in decreased C5a level with MMA and ET but increased level with BMA. Discussion: The functional groups exposed on the surface of a material influence whether leukocyte or platelet activation is responsible for the subsequent physiological response. By modifying the combinations of surface acid concentrations and comonomers, we show that a biomaterial with an appropriate surface chemistry promotes the platelet plug formation and coagulation but down regulated foreign body reaction. This study shows that that a biomaterial with the appropriate surface chemistry to evoke the same coagulation response as damaged tissue, mediated through platelet activation and intrinsic and extrinsic coagulation, initiates the initial pathways of the bone healing cascade. This material is a realistic candidate for biomaterial induced bone regeneration