Benefit of percutaneous injection of autologous platelet-leukocyte-rich gel in patients with delayed union and nonunion

Orthobiologics in delayed union and non-union of adult long bones fractures: A systematic review

Background

Fracture healing poses a significant challenge in orthopedics. Successful regeneration of bone is provided by mechanical stability and a favorable biological microenvironment. This systematic review aims to explore the clinical application of orthobiologics in treating aseptic delayed union and non-union of long bones in adults.

Methods

A systematic review was conducted following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Three databases were explored, with no date restrictions, using keywords related to orthobiologics and delayed union and non-union. Eligible studies included human clinical studies in English, with available full texts, examining orthobiologics such as platelet-rich plasma (PRP), mesenchymal stem cells (MSCs), and bone morphogenetic protein (BMPs) for treating aseptic delayed unions and non-unions in adults. Animal studies, in vitro research, and studies on non-unions due to congenital defects, tumors or infections were excluded.

Results

The initial search identified 9417 studies, with 20 ultimately included in the review. These studies involved 493 patients affected by non-union and 256 patients affected by delayed union, with an average age respectively of 40.62 years and 41.7 years. The mean follow-up period was 15.55 months for non-unions and 8.07 months for delayed unions. PRP was the most used orthobiologic, and outcomes were evaluated through time to union, functional scores, and clinical examinations. The results indicated that orthobiologics, especially PRP, tended to yield better outcomes compared to surgical procedures without biological factors.

Conclusion

This systematic review suggests that orthobiologics, such as PRP, BMPs, and MSCs, can be effective and safe in the management of delayed union and non-union fractures. These biological treatments have the potential to improve union rates, reduce healing times, and enhance functional outcomes in patients with non-union fractures. Further research is essential to refine treatment protocols and determine the most suitable orthobiologic for specific patient populations and fracture types.

Percutaneous injection of autologous platelet gel accelerate healing in diabetic tibial non union: On going longitudinal study

INTRODUCTION

In this study the tibial shaft fracture non unions in diabetes mellitus are evaluated with percutaneous autologous platelet gel supplementation to accelerate union are compared with individually matched control group with autologous iliac crest bone marrow aspirate injection.

MATERIAL AND METHODS

This present study was carried out on tibial non unions in diabetic patients recruited in an ongoing longitudinal study over a period of 2006 to 2017, treated by one surgeon at one institute, are included in this report. Each of 18 established tibial atrophic, aseptic non unions treated by percutaneous autologous platelets and iliac crest bone marrow aspirate were followed up on regular basis up till 9 months. The healing of non union was assessed clinically by painless full weight bearing and the radiological union was judged by bridging callus formation observed on at least 3 of 4 cortices in anteroposterior and lateral views.

RESULTS

Union was observed in 17 (94.4 %) patients of the autologous platelet group. The average time to union was 9.2 weeks (range 8 to 18 weeks) after percutaneous autologous platelet injection (P < 0.0517) .In the control group, union was observed in 14 (77.8 %) patients (P = 0.672). The average time to union following percutaneous bone marrow injection was 11.6 weeks (range 9 to 28 weeks). The proximal 1/3 shaft non union healed comparatively faster than the distal 1/3 shaft tibia (P ≤ 0.0612). No correlation was observed between the comminuted and non comminuted fracture non union (P = 0.789). A significant correlation was noted as regards the non union healing time duration in patients who were on insulin and oral hypoglycemic drugs (P ≤ 0.001) and also about the total duration of diabetes mellitus in years (P ≤ 0.003).

CONCLUSION

This investigation showed that percutaneous autologous platelet gel delivery is sufficient method to obtain union in diabetic tibial fracture non unions, which is less invasive procedure than bone marrow injection. The efficacy of this autologous platelets is once again well established and this study reinforced categorically the previously published report by the author.

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

Autologous Platelet and Extracellular Vesicle-Rich Plasma as Therapeutic Fluid: A Review

The preparation of autologous platelet and extracellular vesicle-rich plasma (PVRP) has been explored in many medical fields with the aim to benefit from its healing potential. In parallel, efforts are being invested to understand the function and dynamics of PVRP that is complex in its composition and interactions. Some clinical evidence reveals beneficial effects of PVRP, while some report that there were no effects. To optimize the preparation methods, functions and mechanisms of PVRP, its constituents should be better understood. With the intention to promote further studies of autologous therapeutic PVRP, we performed a review on some topics regarding PVRP composition, harvesting, assessment and preservation, and also on clinical experience following PVRP application in humans and animals. Besides the acknowledged actions of platelets, leukocytes and different molecules, we focus on extracellular vesicles that were found abundant in PVRP.

Blood Conservation Techniques and Strategies in Orthopedic Anesthesia Practice

Orthopedic surgery procedures involving joint arthroplasty, complex spine, long bone and pelvis procedure, and trauma and oncological cases can be associated with a high risk of bleeding and need for blood transfusion, making efforts to optimize patient care and reduce blood loss very important. Patient blood management programs incorporate efforts to optimize preoperative anemia, develop transfusion protocols and restrictive hemoglobin triggers, advance surgical and anesthesia practice, and use antifibrinolytic therapies. Perioperative management of anticoagulant therapies, a multidisciplinary decision-making task, weighs in risks and benefits of thromboembolic risk and surgical bleeding and is patient- and surgery-specific.

Therapeutic Efficacy and Safety of Osteoinductive Factors and Cellular Therapies for Long Bone Fractures and Non-Unions: A Meta-Analysis and Systematic Review

BACKGROUND

Long bone fractures display significant non-union rates, but the exact biological mechanisms implicated in this devastating complication remain unclear. The combination of osteogenetic and angiogenetic factors at the fracture site is an essential prerequisite for successful bone regeneration. The aim of this study is to investigate the results of the clinical implantation of growth factors for intraoperative enhancement of osteogenesis for the treatment of long bone fractures and non-unions.

METHODS

A systematic literature review search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in the PubMed and Web of Science databases from the date of inception of each database through to 10 January 2022. Specific inclusion and exclusion criteria were applied in order to identify relevant studies reporting on the treatment of upper and lower limb long bone non-unions treated with osteoinductive or cellular factors.

RESULTS

Overall, 18 studies met the inclusion criteria and examined the effectiveness of the application of Bone Morphogenetic Proteins-2 and -7 (BMPs), platelet rich plasma (PRP) and mesenchymal stem cells (MSCs). Despite the existence of limitations in the studies analysed (containing mixed groups of open and close fractures, different types of fractures, variability of treatment protocols, different selection criteria and follow-up periods amongst others), their overall effectiveness was found significantly increased in patients who received them compared with the controls (I2 = 60%, 95% CI = 1.59 [0.99-2.54], Z =1.93, p = 0.05).

CONCLUSION

Administration of BMP-2 and -7, PRP and MSCs were considered effective and safe methods in fracture treatment, increasing bone consolidation, reducing time to repair and being linked to satisfactory postoperative functional scores.

Cortical allograft strut augmented with platelet-rich plasma for the treatment of long bone non-union in lower limb- a pilot study

Background

The autogenous iliac bone graft is the first choice of surgical treatment for long bone non-union. However, many factors limit the use of autogenous bone, such as insufficient bone harvest and complications in the donor site. This study aimed to pilot-test the effectiveness of the cortical allograft strut augmented with Platelet-rich plasma (PRP) on long bone non-union in the lower limb.

Method

This study was a one-armed pilot trial, with thirteen men and four women patients scheduled for surgery. Revision surgery for managing long bone non-union included debridement, internal fixation of the cortical allograft strut, and adding PRP in the fracture site. After surgery, outcome measurements of healing rate, healing time, the incidence of revision, and complications, were assessed at least one-year follow-up.

Results

Fourteen of seventeen participants completed all follow-ups. The mean age of 14 patients was 35.9 years (range, 18–56 years), and the mean BMI was 22.44 ± 1.53 kg/m². All nonunions united after the operation. The mean healing time was 4.6 ± 0.7 months. There was no revision or complication.

Conclusion

Cortical allograft strut augmented with PRP led to healing long bone non-union in the lower limb. More clinical research is required before widespread use.

Ultrasound-guided injection of platelet-rich plasma or cord blood platelet-rich plasma in nonunion: a randomized controlled trial

Aim: To compare the ability of autologous platelet-rich plasma (PRP) and cord blood PRP (PRPc) to accelerate bone healing. Patients & methods: 71 patients with mechanically stable nonunion were treated weekly (3 consecutive weeks) with ultrasound-guided percutaneous injections of PRP or PRPc in a controlled randomized clinical trial. The primary outcome was healing (12 months) and secondary outcomes were radiological evolution (2 and 6 months) and changes in pain intensity (6 months). Results & conclusion: Bone consolidation was assessed over time without significant differences between PRP and PRPc treatment. In patients with persistent nonunion, pain perception decreased more after PRP treatment. PRPc appears to be a valid alternative when specific clinical conditions suggest avoiding the use of autologous blood products.

Clinical Effectiveness of Platelet-Rich Plasma for Long-Bone Delayed Union and Nonunion: A Systematic Review and Meta-Analysis

Background

More recently, there was a series of clinical studies focusing on local administration of platelet-rich plasma (PRP) in long-bone fracture patients suffering from delayed union and nonunion. Therefore, we performed a systematic review to evaluate the effectiveness of PRP injection for treatment of patients with long-bone delayed union and nonunion.

Methods

Relevant clinical trials were selected by the main bibliographic databases, including Medline, PubMed, Embase, Web of Science, and the Cochrane library, to evaluate the effectiveness of PRP for long-bone fracture patients diagnosed with delayed union or nonunion by two reviewers independently. The main outcomes included healing rate, healing duration, pain relief, functional outcome, and complications.

Results

Finally, thirteen studies including four hundred and fifty-nine participants met the selection criteria and were included in this systematic review. These articles included three randomized controlled studies, one prospective study, and nine retrospective studies. 146 out of 155 (94.19%) patients treated with PRP during operation, and 144 out of 183 (78.69%) patients treated with PRP injection alone, exhibited bone consolidation. The healing rate of the PRP group (85.80%) was higher than that of the control group (60.76%). The mean bony union time of patients treated and untreated with PRP, were, respectively, 4.64 and 5.15 months. Four papers reported that PRP was effective in pain relief of patient with delayed union and nonunion. Complications, including small subcutaneous hematoma, subcutaneous swelling, and postoperative infection, were also reported in enrolled studies.

Conclusions

PRP is a promising alternative treatment for patients with long-bone delayed union and nonunion. PRP could successfully promote the healing rate and relieve the pain of patients with delayed union and nonunion. However, the long-term adverse side and functional outcome in application of PRP still need further large-scale trials and long-term follow-up.

Systematic Review Registration

https://www.researchregistry.com/browse-the-registry#home/registrationdetails/61dbd2f837e948001e68d5c5/, The identifying number is research registry 7525.

The role of Platelet Rich Plasma and other orthobiologics in bone healing and fracture management: A systematic review

BACKGROUND

Treatment of large bone defects and fracture healing complications (delayed and non-union) presents a substantial challenge for orthopaedic surgeons. Given that bone healing requires mechanical stability as well as a favourable biological microenvironment, orthobiologics such as Platelet-Rich Plasma (PRP) may have a significant clinical role to play.

AIMS

To perform a systematic review of the available literature to assess the clinical effect of PRP, with or without other orthobiologics, on bone healing.

METHOD

Two independent reviewers performed the literature search based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Clinical studies of any evidence, assessing effect of PRP with or without other orthobiologics on bone healing, were included. A qualitative analysis was carried out on the clinical and radiological outcomes reported.

RESULT

27 articles with 1631 patients (mean age = 43.56, 57.1% male, mean follow-up = 17.27 months) were included in the qualitative. Of the 27 studies, 13 dealt with fracture complications (delayed or non-unions), 7 with acute fracture healing, 4 with tibial osteotomies and lengthening procedures and 3 with lumbar spine pathology. 18/27 studies showed a clinical benefit of PRP, 8/27 showed no significant effect, and 1/27 showed a worse outcome with PRP.

CONCLUSION

Our review suggests PRP may play a clinical role in bone healing but further randomised controlled trials (RCTs) using standardised outcomes should be performed to establish its efficacy.

Platelet-Rich Plasma, Mesenchymal Stem Cell, and Non-metallic Suture-Based Fixation Technique in a Patellar Fracture Nonunion: A Technical Note and Systematic Review

Backgroud

We performed a systematic review on the management of patellar fracture nonunion and report a novel suture-based non-metallic fixation technique associated with platelet-rich plasma and mesenchymal stem cell injections in the management of this injury.

Methods

A systematic search was performed up to August 2020 in PubMed and Scopus electronic databases of scholarly articles evaluating different surgical techniques used for nonunion of patellar fractures, with no restrictions on language or year of publication. Furthermore, we describe our novel non-metallic suture fixation technique and a patient in whom this technique was applied.

Results

A total of 9 articles were included in the systematic review. Tension band wiring was the most commonly used procedure (62.7%). Nonoperative procedures (8.1%) resulted in nonunion in all patients. The most common complication after open reduction and internal fixation was infection (7.8%). Our patient at the latest follow-up reported full functional recovery and full extension and flexion of the affected knee with no pain and subjectively normal strength.

Conclusions

The management of patella nonunions is still a challenge. The technique reported here can be used in patellar fracture nonunion, as well as in primary patellar fractures.

Benefits of autologous platelet tissue graft in wound healing after corneal refractive surgery: a case report

Background

Corneal refractive surgeries cause epithelial damage and induce wound healing processes. To promote wound healing after photorefractive keratectomy, the effectiveness of an autologous platelet tissue graft was assessed.

Case presentation

A 45-year-old Asian male with low myopia and/or myopic astigmatism received photorefractive keratectomy in both eyes. The right eye was postoperatively treated with an autologous platelet tissue graft using the GPS III Platelet Concentration System to prepare platelet-rich plasma, while the left eye was not treated. Both eyes achieved the expected uncorrected distance visual acuity, but the platelet-rich-plasma-treated right eye obtained improved visual acuity more than 1 week before the untreated left eye. Perceived pain after photorefractive keratectomy was much lower and of shorter duration in the treated right eye than it was for the left eye. Pericorneal injection on the bulbar conjunctiva with superficial keratitis resolved earlier in the right eye than the left eye.

Conclusions

Autologous platelet tissue grafting using a GPS III to obtain platelet-rich plasma was effective in promoting corneal wound healing after photorefractive keratectomy. Thus, platelet-rich plasma may be beneficial for patients undergoing corneal refractive surgeries.

The Use of Platelet-Rich Plasma (PRP) for the Management of Non-union Fractures

PURPOSE OF REVIEW

The treatment of non-union fractures represents a significant challenge for orthopaedic surgeons. In recent years, biologic agents have been investigated and utilised to support and improve bone healing. Among these agents, platelet-rich plasma (PRP) is an emerging strategy that is gaining popularity. The aim of this review is to evaluate the current literature regarding the application and clinical effectiveness of PRP injections, specifically for the treatment of non-union fractures.

RECENT FINDINGS

The majority of published studies reported that PRP accelerated fracture healing; however, this evidence was predominantly level IV. The lack of randomised, clinical trials (level I-II evidence) is currently hampering the successful clinical translation of PRP as a therapy for non-union fractures. This is despite the positive reports regarding its potential to heal non-union fractures, when used in isolation or in combination with other forms of treatment. Future recommendations to facilitate clinical translation and acceptance of PRP as a therapy include the need to investigate the effects of administering higher volumes of PRP (i.e. 5-20 mL) along with the requirement for more prolonged (> 11 months) randomised clinical trials.

Evidence-Based Clinical Efficacy of Leukocyte and Platelet-Rich Fibrin in Maxillary Sinus Floor Lift, Graft and Surgical Augmentation Procedures

Bone augmentation techniques have increasingly been indicated for re-creating adequate bone height and volume suitable for dental implant sites. This is particularly applicable in the severely atrophic posterior maxilla where sinus perforation (ruptured Schneiderian membrane) is a very common complication and sinus floor elevation or lift is frequently considered a standard procedure. The augmentation of the maxillary sinus can be performed with or without grafting biomaterials. Herein, numerous biomaterials and bone substitutes have been proposed, primarily to sustain the lifted space. In addition, cytokines and growth factors have been used to stimulate angiogenesis, enhance bone formation as well as improve healing and recovery period, either as the sole filling material or in combination with bone substitute materials. Within such, is the family of autologous blood extracts, so-called platelet concentrates, which are simply the "product" resulting from the simple centrifugation of collected whole blood samples of the patient, immediately pre-surgery. Platelet-Rich Fibrin (PRF), a sub-family of platelet concentrates, is a three-dimensional (3-D) autogenous biomaterial obtained, without including anti-coagulants, bovine thrombin, additives, or any gelifying agents during the centrifugation process. Today, it is safe to say that, in implant dentistry and oral and maxillofacial surgery, PRFs (particularly, the pure platelet-rich fibrin or P-PRF and leukocyte and platelet-rich fibrin or L-PRF sub-classes) are receiving the most attention, essentially due to their simplicity, rapidness, user-friendliness/malleability, and cost-effectiveness. Whether used as the sole "bioactive" filling/additive material or combined with bone substitutes, the revolutionary second-generation PRFs have been very often associated with promising clinical results. Hence, this review aims to provide a 10-years update on the clinical effectiveness of L-PRF when applied/used as the "sole" biomaterial in maxillary sinus augmentation procedures. An electronic search using specific keywords for L-PRF and maxillary sinus augmentation was conducted in three main databases (PubMed-MEDLINE database, Google Scholar and Cochrane library) for the period between January 2009-February 2020. The quest yielded a total of 468 articles. Based on the pre-established strict inclusion/exclusion criteria, only seven articles were deemed eligible and included in the analysis. Surprisingly, of the 5 studies which used de-proteinized bovine bone mineral (DBBM) in combination with L-PRF, 60% acclaimed no significant effects and only 40% declared positive effects. Of the two articles which had used allogenous bone graft, 50% declared no significant effects and 50% acclaimed positive effects. Only one study had used L-PRF as the sole grafting material and reported a positive effect. Likewise, positive effects were reported in one other study using L-PRF in combination with a collagen membrane. Due to the heterogeneity of the included studies, this review is limited by the inability to perform a proper systematic meta-analysis. Overall, most of the published studies reported impressive results of L-PRF application as a grafting material (sole or adjuvant) in maxillary sinus augmentation and dental implant restorative procedures. Yet, distinct technical processing for L-PRF preparation was noted. Hence, studies should be approached with caution. Here in, in sinus lift and treatment of Schneider membrane, the formation of mature bone remains inconclusive. More studies are eagerly awaited in order to prove the beneficial or detrimental effects of PRFs, in general and L-PRFs, in specific; especially in their tissue regenerative potential pertaining to the promotion of angiogenesis, enhancing of cell proliferation, stimulation of cell migration and autocrine/paracrine secretion of growth factors, as well as to reach a consensus or a conclusive and distinct determination of the effect of leukocytes (and their inclusion) on inflammation or edema and pain; a call for standardization in PRFs and L-PRFs composition reporting and regimenting the preparation protocols.

Effect of platelet-rich plasma and platelet-rich fibrin matrix on healing of vertical meniscal tears in a rabbit model

OBJECTIVE

This study aimed to investigate the effect of platelet-rich plasma (PRP) and platelet-rich fibrin matrix (PRFM) on the healing of vertical medial meniscal tears in a rabbit model.

METHODS

The study was conducted on 72 New Zealand mature rabbits aged more than 6 months. Rabbits were randomly assigned to six groups: control (C) group, meniscal repair (MR) group, PRP group, PRFM group, MR+PRP group, and MR+PRFM group, with 12 rabbits in each group. A 5-mm full-thickness vertical tear was created in the avascular zone of the medial meniscus corpus in the right knee of all rabbits. The respective treatment for each group was given to the meniscal tear in each rabbit. Histological evaluation of healing was performed 6 and 12 weeks after surgery.

RESULTS

Defect filling and collagen formation remained low in the C group. However, in all other groups, there was no significant difference in the 6th week. In the 12th week, similar results as those obtained in the 6th week were obtained. In the C group, there was a difference in defect filling and cell type. This difference was that the defect filling and collagen formation remained low in the 12th week. No significant difference was observed between MR, MR + PRP and MR + PRFM groups. The MR group significantly differed from the other groups in the defect-filling rate and cell type; however, the use of PRP and PRFM did not provide an obvious benefit.

CONCLUSION

The contradictory results obtained in previous studies emphasize the need for further research on the use of PRP in meniscal recovery and repair. We believe that if surgery is indicated, repair is absolutely necessary to improve the healing of the tissue in meniscal tears. Studies using human meniscal tissue for meniscal injury and those that evaluate clinical applications of PRP are warranted.

A Prospective, Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Study Evaluating Meniscal Healing, Clinical Outcomes, and Safety in Patients Undergoing Meniscal Repair of Unstable, Complete Vertical Meniscal Tears (Bucket Handle) Augmented with Platelet-Rich Plasma

OBJECTIVE

The present study aimed to investigate the effectiveness and safety of platelet-rich plasma (PRP) application in arthroscopic repair of complete vertical tear of meniscus located in the red-white zone.

METHODS

This single center, prospective, randomized, double-blind, placebo-controlled, parallel-arm study included 37 patients with complete vertical meniscus tears. Patients received an intrarepair site injection of either PRP or sterile 0.9% saline during an index arthroscopy. The primary endpoint was the rate of meniscus healing in the two groups. The secondary endpoints were changes in the International Knee Documentation Committee (IKDC) score, Knee Injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and analog scale (VAS) in the two groups at 42 months.

RESULTS

After 18 weeks, the meniscus healing rate was significantly higher in the PRP-treated group than in the control group (85% versus 47%, P = 0.048). Functional outcomes were significantly better 42 months after treatment than at baseline in both groups. The IKDC score, WOMAC, and KOOS were significantly better in the PRP-treated group than in the control group. No adverse events were reported during the study period.

CONCLUSIONS

The findings of this study indicate that PRP augmentation in meniscus repair results in improvements in both meniscus healing and functional outcome.

The application of L-PRP in AIDS patients with crural chronic ulcers: A pilot study

PURPOSE

Nonhealing wounds or skin ulcerations are the result of insufficient repair and destruction of a local healing potential. Opportunistic infections which cause a lot of ulcer complications influence the worsening general condition of patients with AIDS, ultimately leading to death. The chronicity of the condition and poor results of conventional therapy have prompted the search for new methods of treatment.

MATERIALS AND METHODS

We have examined venous or arteriovenous insufficiency-related extensive crural ulcers in AIDS patients. Crural ulcer healing processes were evaluated with clinical observations and histopathological, immunohistochemical and molecular examinations of tissue samples harvested from the wound edges before and on day 10 after L-PRP cover dressing.

RESULTS

Clinical observations showed positive effects of L-PRP in all patients. However, complete wound closure was noted in 60% of cases. Statistical analysis of histological examination showed increased epidermal processes between samples, but the difference was nonsignificant. However, immunohistochemical investigations showed an increased healing process with strong statistical significance. The mean VEGF level before L-PRP usage was 114.3 vessels/mm² and on day 10 118.9 (p=0.001523). The mean FLK level was 103.2 and 109.9 respectively (p=0.008241). The biggest differences were observed for CD34, with values of 68.2 on day 0 and 100.8 on day 10 (p=0.006982). Molecular analysis generally showed decreased gene expression and confirmed vascular formation and reepithelialization processes.

CONCLUSIONS

In our opinion, L-PRP may be used to eradicate microorganisms from wounds, to induce neovascularization, and in unhealed cases prepare the base and edge of the ulcer for skin grafting and tissue expansion procedures.

Role of isolated percutaneous autologous platelet concentrate in delayed union of long bones

PURPOSE

The objective of this study is to evaluate the efficacy of percutaneous platelet concentrate (PC) injection in increasing the chances of attaining union in delayed union of long bones and to know whether the time taken for union decreases with use of PC.

METHODS

Forty delayed unions (15-30 weeks old) were randomized into a study group in which autologous PC prepared by blood bank centrifuge was percutaneously injected at the fracture site under image intensifier after activation with 10% calcium gluconate and a control group where patients were observed over time. Follow-up was every 6 weeks till fracture union. At each follow-up visit clinical and radiological parameters of union were assessed.

RESULTS

Percentage union was 78% (18/23) in PC group and 59% (10/17) in control group, respectively (p = 0.296). The mean time to fracture union treated with PC (15.33 ± 9.91 weeks) was not different from the control group (13.10 ± 7.21 weeks; p = 0.540). In the PC group union is seen in 12 weeks after PC injection in 60 per cent of the cases.

CONCLUSION

Isolated percutaneous PC injection increases union rates in delayed union of long bones. The results were, however, not statistically significant but show high positive association. Further studies are required to recommend routine use of PC injection.

Use of autologous platelet-rich plasma for a delayed consolidation of a tibial fracture in a young donkey

A 9-month-old filly donkey was referred for a comminuted diaphyseal fracture of the right tibia. Surgical osteosynthesis, with multiple lag screws and a neutralization plate, was performed for anatomical reconstruction. Despite a good gait condition, delayed bone consolidation and a bone gap were evident on follow up radiographic evaluations. Due to delayed healing, autologous platelet-rich plasma (PRP) was injected on the surface of the tibia. Increased bone consolidation was evident on radiographs one month after the PRP injection. Progressive filling of both the fracture lines and bone gap continued during the six-month follow up. Clinical outcome was excellent. Autologous PRP should be considered as a practical adjuvant therapy in bone healing process in donkeys.

Role of Recombinant Human Bone Morphogenetic Protein-2 on Hindfoot Arthrodesis

Despite advances in understanding bone healing physiology and surgical techniques, delayed union and nonunion still occur after the treatment of hindfoot arthrodesis. There is increasing appeal of bone morphogenetic proteins (BMPs) owing to the innate osteoinductive abilities of BMPs. Effective treatment with BMPs has been shown in animal studies. Human clinical studies have also shown success. The only study investigating the use of recombinant human BMP (rhBMP)-2 in hindfoot arthrodesis found a significant increase in fusion rate. Treatment cost effective. Complications from their use remain low. rhBMP-2 is a safe and effective bone-healing adjunct in hindfoot arthrodesis surgery.

Platelet-rich plasma for the treatment of bone defects: from pre-clinical rational to evidence in the clinical practice. A systematic review

PURPOSE

The treatment of large bone defects represents a significant challenge for orthopaedic surgeons. In recent years, biologic agents have also been used to further improve bone healing. Among these, platelet-rich plasma (PRP) is the most exploited strategy. The aim of the present study was to systematically review the available literature to identify: 1) preclinical in-vivo results supporting the rational of PRP use for bone healing; 2) evidence from the clinical practice on the actual clinical benefit of PRP for the treatment of fractures and complications such as delayed unions and non-unions.

METHODS

A systematic review of the literature was performed on the application of PRP in bone healing, using the following inclusion criteria: pre-clinical and clinical reports of any level of evidence, written in English language, published in the last 20 years (1996-2016), on the use of PRP to stimulate long-bone defect treatment, with focus on fracture and delayed/non-unions healing.

RESULTS

The search in the Pubmed database identified 64 articles eligible for inclusion: 45 were preclinical in-vivo studies and 19 were clinical studies. Despite the fact that the overall pre-clinical results seem to support the benefit of PRP in 91.1 % of the studies, a more in depth analysis underlined a lower success rate, with a positive outcome of 84.4 % in terms of histological analysis, and even lower values considering radiological and biomechanical results (75.0 % and 72.7 % positive outcome respectively). This was also mirrored in the clinical literature, where the real benefit of PRP use to treat fractures and non-unions is still under debate.

CONCLUSION

Overall, the available literature presents major limitations in terms of low quality and extreme heterogeneity, which hamper the possibility to optimize PRP treatment and translate it into a real clinical benefit despite positive preclinical findings on its biological potential to favour bone healing.

Autologous platelet lysates local injections for treatment of tibia non-union with breakage of the nickelclad: a case report

Background

Nonunions of the tibia represent challenging orthopedic problems, which require the surgeon to analyze numerous factors and choose an appropriate treatment. This article presents a case report of tibia and fibula fracture patient who failed the internal fixation surgery and successfully recovered after one course of percutaneous autologous platelet lysates injection.

Case description

The patient received an internal nickelclad breakage at 9 months post-surgery but reluctant to accept a second surgery, then autologous platelet lysates (APL) injection which is a less invasive method was recommended. The injections were carried once a week for three times. Radiologic evaluation was conducted every month until recovery.

Discussion and evaluation

To the best of our knowledge, this is the first reported case of tibia delayed union with breakage of the plate resolved with APL injection. Improved clinical evidence was observed at 4 and 6 months after injection. The patient got good bony union at 8 months post-injection. The patient didn’t feel any discomfort postinjection, no complications such as infection, refracture etc. were observed.

Conclusions

APL percutaneous injection could be a new therapeutic option for the treatment of nonunion or delayed healing fractures.

The role of TGF-β1/Smad2/3 pathway in platelet-rich plasma in retarding intervertebral disc degeneration

Recent studies have suggested that platelet‐rich plasma (PRP) injections are an effective way to retard intervertebral disc degeneration, but the mechanism of action is unclear. Activated platelets release some growth factors, such as transforming growth factor‐β1 (TGF‐β1), which positively modulate the extracellular matrix of nucleus pulposus cells. The purpose of this study was to explore the mechanism underlying the PRP‐mediated inhibition of intervertebral disc degeneration. In an in vitro study, we found that the proliferation of nucleus pulposus cells was greatly enhanced with 2.5% PRP treatment. The TGF‐β1 concentration was much higher after PRP treatment. PRP administration effectively increased the collagen II, aggrecan and sox‐9 mRNA levels and decreased collagen X levels. However, Western blotting demonstrated that specifically inhibiting TGF‐β1 signalling could significantly prevent nucleus pulpous cellular expression of Smad2/3 and matrix protein. In a rabbit study, magnetic resonance imaging revealed significant recovery signal intensity in the intervertebral discs of the PRP injection group compared with the very low signal intensity in the control groups. Histologically, the PRP plus inhibitor injection group had significantly lower expression levels of Smad2/3 and collagen II than the PRP group. These results demonstrated that a high TGF‐β1 content in the platelets retarded disc degeneration in vitro and in vivo. Inhibiting the TGF‐β1/Smad2/3 pathway could prevent this recovery by inactivating Smad2/3 and down‐regulating the extracellular matrix. Therefore, the TGF‐β1/Smad2/3 pathway might play a critical role in the ability of PRP to retard intervertebral disc degeneration.

Investigating the effect of intra-articular PRP injection on pain and function improvement in patients with distal radius fracture

INTRODUCTION

Distal radius fractures are common injuries that cause pain and disability. There is a clear need for biomedical engineering research to develop novel strategies to improve functional results following intra-articular distal radius fractures. However, no pharmacotherapeutic agent has been investigated to resolve this problem. The aim of this study was to evaluate whether the platelet-rich plasma (PRP) can be considered a novel additional therapy to improve the outcomes of this injury.

HYPOTHESIS

Pain reduction and functional improvement can be noticed after PRP use in distal radius fracture.

MATERIALS AND METHODS

A randomized trial study was designed with 30 patients who had intra-articular distal radius fractures (Frykman type 3, 4, 7, 8). Closed reduction and percutaneous pinning under guide of fluoroscopy were done for them. Fifteen cases received intra-articular autologus PRP. Patients were followed for 3 and 6 months and "patient-rated wrist evaluation" (PRWE) questionnaire was completed and range of motion of the wrist was measured.

RESULTS

The mean of pain score and the score of specific and usual activities at 3 months follow-up in the case group and in the control group were (8.33 versus 19.67), (10.66 versus 26.8), and (6.2 versus 13.4), respectively. The mean of pain score and score of specific and usual activities at 6 months follow-up in the case group and in the control group were (3.6 versus 12), (3 versus 15.7), and (1.2 versus 6.8), respectively. The case group was significantly different from the control group. The mean of loss of flexion and extension of the wrist at 3 months follow-up in the case group was significantly different from the control group as well.

CONCLUSION

PRP may have significant effect on reduction of pain and amount of difficulty in functions, including specific and usual activities after intra-articular distal radius fractures.

LEVEL OF EVIDENCE

Level III, Therapeutic trial.

Management of Aseptic Tibial and Femoral Diaphyseal Nonunions Without Bony Defects

An evidence-based description of aseptic tibial and femoral diaphyseal nonunions without segmental defects is based on a systematic search of MEDLINE. Aseptic nonunion of the femoral or tibial diaphysis without segmental defects and with an in situ nail, treated with reamed exchange nailing or augmentative plating and bone grafting, has consistently high union rates. Aseptic nonunion without segmental defects and with in situ plate and screw fixation is best managed with revision plate and screw fixation and autogenous bone graft. Various techniques and methods of biological stimulation have relatively high union rates.

Role of autologous platelet-rich plasma in treatment of long-bone nonunions: a prospective study

PURPOSE

Fracture union is a complex biological process, which depends upon several systemic and local factors. Disturbance of any of these factors may lead to nonunion of the fracture. These nonunions have a huge impact on quality of life as well as socioeconomical aspects. The platelets on activation release a number of growth factors and differentiation factors, which play important role in fracture healing. This study aimed to look for efficacy of platelet-rich plasma in the treatment of established fracture nonunions of long bones.

METHODS

A total of 94 patients with established nonunion of long bone (35 tibia, 30 femur, 11 humerus, 4 radius, 12 ulna, 2 with both radius and ulna) were included in this study. We injected 15-20 ml of autologous platelet-rich plasma (>2,000,000 platelets/μl) under image intensifier at each nonunion site. The fracture union was evaluated clinically and radiologically regularly at monthly interval till 4 months.

RESULTS

Eighty-two patients had their fracture united at the end of 4 months. Thirty-four patients showed bridging trabeculae on X-rays at the end of 2 months, while 41 patients showed bridging trabeculae at the end of third month. Twelve patients did not show any attempt of union at 4 months and were labeled as failure of treatment. There were no complications.

CONCLUSION

Platelet-rich plasma is a safe and effective treatment for the treatment of nonunions. More studies are needed to look into molecular mechanism of this fracture healing acceleration by platelet-rich plasma.

Inflammation, Bone Healing, and Anti-Inflammatory Drugs: An Update

Fracture healing is a unique multifaceted process requiring the presence of cells, molecular mediators, and angiogenic factors. The state of inflammation dominates the initial phase, but the ideal magnitude and duration of the process for an optimal outcome remains obscure. Biological response modifiers, such as platelet-rich plasma (PRP) preparations, have been used to reconstitute the desirable early inflammatory state, but the results obtained remain inconclusive. Ongoing research to characterize and quantify the inflammatory response after bone fracture is essential in order to better understand the molecular insights of this localized reaction and to expand our armamentarium in the management of patients with an impaired fracture healing response. Non-steroidal anti-inflammatory drugs frequently administered for analgesia after trauma procedures continue to be a cause of concern for a successful bone repair response.

Efficacy of platelet-rich plasma in arthroscopic repair of full-thickness rotator cuff tears: a meta-analysis

BACKGROUND

The use of platelet-rich plasma (PRP) is an innovative clinical therapy, especially in arthroscopic rotator cuff repair. The purpose of this study was to compare the clinical improvement and tendon-to-bone healing with and without PRP therapy in arthroscopic rotator cuff repair.

METHODS

A systematic search was done in the major medical databases to evaluate the studies using PRP therapy (PRP+) or with no PRP (PRP-) for the treatment of patients with rotator cuff tears. We reviewed clinical scores such as the Constant score, the American Shoulder and Elbow Surgeons score, the University of California at Los Angeles (UCLA) Shoulder Rating Scale, the Simple Shoulder Test, and the failure-to-heal rate by magnetic resonance imaging between PRP+ and PRP- groups.

RESULTS

Five studies included in this review were used for a meta-analysis based on data availability. There were no statistically significant differences between PRP+ and PRP- groups for overall outcome scores (P > .05). However, the PRP+ group exhibited better healing rates postoperatively than the PRP- group (P = .03) in small/moderate full-thickness tears.

CONCLUSION

The use of PRP therapy in full-thickness rotator cuff repairs showed no statistically significant difference compared with no PRP therapy in clinical outcome scores, but the failure-to-heal rate was significantly decreased when PRP was used for treatment of small-to-moderately sized tears. PRP therapy may improve tendon-to-bone healing in patients with small or moderate rotator cuff tears.

Effect of Leukocyte-Rich and Platelet-Rich Plasma on Healing of a Horizontal Medial Meniscus Tear in a Rabbit Model

There are limited reports on the effect of platelet-rich plasma (PRP) on meniscus healing. The purpose of this study was to investigate the effect of leukocyte-rich PRP (L-PRP) on potential healing of the horizontal medial meniscus tears in a rabbit model. A horizontal medial meniscus tear was created in both knees of nine skeletally mature adult rabbits. Left or right knees were randomly assigned to a L-PRP group, or a control group. 0.5 mL of L-PRP from 10 mL of each rabbit's whole blood was prepared and injected into the horizontal tears in a L-PRP group. None was applied to the horizontal tears in a control group. The histological assessment of meniscus healing was performed at two, four, and six weeks after surgery. We found that there were no significant differences of quantitative histologic scoring between two groups at 2, 4, and 6 weeks after surgery (p > 0.05). This study failed to show the positive effect of single injection of L-PRP on enhancing healing of the horizontal medial meniscus tears in a rabbit model. Single injection of L-PRP into horizontal meniscus tears may not effectively enhance healing of horizontal medial meniscus tears.

Role of platelet-released growth factors in detoxification of reactive oxygen species in osteoblasts

INTRODUCTION

Oxidative stress can impair fracture healing. To protect against oxidative damage, a system of detoxifying and antioxidative enzymes works to reduce the cellular stress. The transcription of these enzymes is regulated by antioxidant response element (ARE). The nuclear factor (erythroid-derived 2)-like2 (Nrf2) plays a major role in transcriptional activation of ARE-driven genes. Recently it has been shown that vascular endothelial growth factor (VEGF) prevents oxidative damage via activation of the Nrf2 pathway in vitro. Platelet-released growth factor (PRGF) is a mixture of autologous proteins and growth factors, prepared from a determined volume of platelet-rich plasma (PRP). It has already used to enhance fracture healing in vitro. The aim of the present study was to elucidate if platelets can lead to upregulation of VEGF and if platelets can regulate the activity of Nrf2-ARE system in primary human osteoblast (hOB) and in osteoblast-like cell line (SAOS-2).

METHODS

Platelets and PRGF were obtained from healthy human donors. HOB and SAOS-2 osteosarcoma cell line were used. The ARE activity was analysed using a dual luciferase reporter assay system. We used Western blot to detect the nuclear accumulation of Nrf2 and the amount of cytosolic antioxidant Thioredoxin Reductase-1 (TXNRD-1), Heme Oxygenase-1 (HO-1) and NAD(P)H quinine oxidoreductase-1 (NQO1). Gene expression analysis was performed by real-time RT PCR. ELISA was used for the quantification of growth factors.

RESULTS

The activity of ARE was increased in the presence of PRGF up to 50%. Western blotting demonstrated enhanced nuclear accumulation of Nrf2. This was followed by an increase in the protein expression of the aforementioned downstream targets of Nrf2. Real-time RT PCR data showed an upregulation in the gene expression of the VEGF after PRGF treatment. This was confirmed by ELISA, where the treatment with PRGF induced the protein level of VEGF in both cells.

CONCLUSIONS

These results provide a new insight into PRGF's mode of action in osteoblasts. PRGF not only leads to increase the endogenous VEGF, but also it may be involved in preventing oxidative damage through the Nrf2-ARE signalling. Nrf2 activation via PRGF may have great potential as an effective therapeutic drug target in fracture healing.

Preparation method and growth factor content of platelet concentrate influence the osteogenic differentiation of bone marrow stromal cells

BACKGROUND AIMS

An extensive debate about the clinical benefits of autologous platelet concentrates used as a treatment option for patients with orthopedic injuries is ongoing. The aim of this study was to determine whether different compositions of platelet concentrates may affect the osteogenic differentiation of bone marrow stromal cells (BMSC).

METHODS

Pure platelet-rich plasma (P-PRP) and leukocyte-PRP (L-PRP) were characterized for platelet and leukocyte content. As an indicative marker of the delivery of growth factors (GFs), the release of basic fibroblast growth factor (bFGF) from platelet gel (PG) was measured at 1, 18, 48 and 72 h and at 7 d. The ability of different PGs to induce proliferation and differentiation of BMSC was evaluated by using bioactivity assays.

RESULTS

The platelet recovery was significantly higher in L-PRP, either fresh or frozen. PGs derived from L-PRP and P-PRP showed significant differences in terms of bFGF release and biological activity. bFGF release was faster both in fresh and frozen L-PRP preparations. Moreover, L-PRP samples were able to induce a significantly higher proliferation of BMSC compared with P-PRP or PPP samples. Even though all PG preparations allowed the deposition of mineral nodules in BMSC cultures, the mineralization activity correlated significantly with bFGF levels.

CONCLUSIONS

The biological activity of platelet concentrates differs according to preparation technique, which affects platelet and leukocyte content and GF availability. Because GF levels are not always optimal in subjects with defective bone healing, composition and bioactivity of PRP should be analyzed to test the reliability and potential effectiveness of the regenerative treatment.

Platelet-rich plasma promotes healing of osteoporotic fractures

With an aging population worldwide, the frequency of osteoporotic fractures is increasing. Therefore, biological methods to enhance the internal fixation of osteoporotic fractures becomes more important to reduce the societal burden of care. The purposes of this study were to evaluate the role of platelet-rich plasma (PRP) in the treatment of osteoporotic fractures and to clarify the best concentration of PRP. Bone marrow mesenchymal stem cells isolated from osteoporotic rats were cultured in high- (8.21±0.4×10(9)/mL), medium-(2.65±0.2×10(9)/mL), and low-concentration (0.85±0.16×10(9)/mL) PRP and in platelet-poor plasma (8±0.5×10(6) platelet/mL). The capacities of cell proliferation and osteogenic and adipogenic differentiation were compared. A transverse osteotomy was performed in the middle of the left femoral diaphysis followed by K-wire fixation, and various concentrations of PRP were transplanted into the fracture zone. Radiologic, mechanical, and histologic evaluations were performed at 2, 4, and 8 weeks, respectively. The results indicated that PRP could inhibit adipogenic differentiation and that medium-concentration PRP was effective in inducing the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells derived from osteoporotic bone marrow and in promoting fracture healing, whereas high-concentration PRP inhibited osteogenic differentiation and callus remodeling. Certain concentrations of PRP can effectively enhance the healing of osteoporotic fractures. Medium-concentration PRP is a suitable concentration to use in practice.

Relevance of deep decortication and vascularization in a case of post-traumatic femoral non-union treated with grafts, platelet gel and bone marrow stromal cells

PURPOSE

A male patient suffering from non-union of the femoral diaphysis after a traumatic fracture was treated with deep decortication and grafted with lyophilized bone, platelet gel (PG) and autologous bone marrow stromal cells (BMSCs). After 40 days from surgery, he was re-operated, due to fracture secondary displacement, caused by inappropriate load during sports activity. In addition to radiographs, two bone biopsies were retrieved: this allowed for a histological evaluation of the early response of host bone to the graft. To our knowledge, there is no report describing such early tissue response.

METHODS

A clinical-radiographic evaluation of the patient and a histomorphometric analysis of the bone biopsies were performed.

RESULTS

An early reparative bone formation was observed adjacent to the osteointegrated graft. Non-resorbed bone chips and large islands of non-vital bone particles, surrounded by fibrous tissue, were observed in a zone of sclerotic diaphyseal bone, that is the process was delayed despite decortication.

CONCLUSIONS

These findings support the concept, until now evidenced only by imaging, that bone chips added with PG and BMSCs are effective in shortening the healing time in fracture non-union. The clinical relevance of deep decortication and vascularization is emphasized.

LEVEL OF EVIDENCE

Therapeutic studies-investigating the results of treatment, Level V.

Proliferation and differentiation of human tenocytes in response to platelet rich plasma: an in vitro and in vivo study

Platelet rich plasma (PRP) is the autologous plasma fraction with a platelet-rich cellular component which is enriched with a number of growth factors. Due to its availability and low cost, PRP has become an increasingly popular clinical tool as an alternative source of growth factors for various applications, for example, tendon regeneration but with limited success in clinical trials. The main objective of the current study was to determine whether activated PRP [i.e., platelet rich plasma-clot release (PRCR)] could be used to induce the proliferation and collagen synthesis in human tenocyte in vitro. The advantage of using PRCR is that the platelet-derived bioactive factors are more concentrated and could initiate a more rapid and accelerated healing response than PRP. Our results demonstrated that 10% PRCR treatment accelerated the extent of cell proliferation and collagen production by human tenocytes in vitro. The expression of specific tenocyte markers were similar to conventional fetal bovine serum (FBS)-treated tenocytes implanted in mice within 14 days of implantation in diffusion chambers. Moreover, relatively more collagen fibrils were evident in PRCR-treated tenocytes in vivo as compared to 10% FBS-treated cells. Overall, our feasibility study has indicated that PRCR can induce human tenocyte proliferation and collagen synthesis which could be implemented for future tendon regeneration in reconstructive surgeries.

The effect of platelet-rich plasma on normal soft tissues in the rabbit

BACKGROUND

Platelet-rich plasma is reported to contain multiple growth factors, and has been utilized in orthopaedic surgery to aid healing in multiple tissues. To date, the use of autologous platelet-rich plasma has not been studied for its effects on normal soft tissue.

METHODS

Eighteen adult New Zealand White rabbits were injected with 0.5 mL of autologous platelet-rich plasma in the right or left quadriceps muscle, Achilles tendon, medial collateral ligament, subcutaneous tissue, tibial periosteum, and ankle joint. Saline solution was injected on the contralateral side as a control. The soft tissues were examined histologically at two weeks (six rabbits) and six weeks (six rabbits), and soft tissues from six rabbits that had been reinjected at six weeks were examined at twelve weeks.

RESULTS

Inflammatory skin lesions were visible at forty-eight hours at superficial platelet-rich plasma sites. All lesions resolved by six days. Compared with findings in control specimens, histological analysis of platelet-rich plasma injection sites at two weeks showed a marked inflammatory infiltrate with lymphocytic and monocytic predominance. Intra-articular injection showed villous synovial hyperplasia and chronic synovitis. Tendon and ligament sites showed new collagen deposition. Intramuscular injection sites showed thrombosis, necrosis, and calcium deposition. Subcutaneous sites also showed calcium deposition without necrosis as well as collagen nodules representing early scar tissue. Histological examination of platelet-rich plasma injection sites at six and twelve weeks demonstrated a persistent but diminished inflammatory infiltrate. Focal areas of scar tissue were seen with fibroblasts, collagen formation, and neovascularity. All saline solution sites at all times were nonreactive.

CONCLUSIONS

Platelet-rich plasma can initiate an inflammatory response in the absence of an inciting injury in normal soft tissue in rabbits.

Arthroscopic management and platelet-rich plasma therapy for avascular necrosis of the hip

PURPOSE

The purpose is to describe a noninvasive arthroscopic procedure as an alternative to open surgery for avascular necrosis of the hip.

METHODS

Patients with grade I or IIA avascular necrosis of the hip are treated by core decompression performed by drilling under fluoroscopic guidance. Liquid platelet-rich plasma (PRP) is delivered through a trocar, saturating the necrotic area. In more severe conditions, the necrotic bone is decompressed and debrided, through a cortical window at the head-neck junction. A composite graft made of autologous bone and PRP is delivered by impactation through the core decompression track. Fibrin membranes are applied to enhance healing of the head-neck window and arthroscopic portals. Platelet-rich plasma is infiltrated in the central compartment.

RESULTS

This arthroscopic approach aids in making diagnosis of the labrum and articular cartilage and permits intra-operative treatment decisions. Visual control permits the precise localization and treatment for the necrotic area allowing cartilage integrity to be preserved.

CONCLUSIONS

Arthroscopic management of avascular necrosis of the femoral head is viable and has significant advantages. Clinical studies should justify the theoretical additional benefits of this approach.

Platelets display potent antimicrobial activity and release human beta-defensin 2

Platelet-rich plasma (PRP) is a potent agent that improves soft tissue and bone healing. By the release of growth factors and cytokines, PRP is believed to locally boost physiologic healing processes. Recently, antimicrobial activity of PRP has been demonstrated against S. aureus strains. Major scientific effort is being put into the understanding and prevention of infections i.e. by delivery of antimicrobial substances. In previous studies we showed the ideal antibacterial activity-profile of the human beta-defensin 2 (hBD-2) for orthopaedic infections and therefore hypothesized that hBD-2 may be the effector of antimicrobial platelet action. Platelet concentrates were produced from human platelet phresis obtained from a hospital blood bank. They were screened by immunohistochemistry, Western Blot and ELISA for the human beta defensin-2. In vitro susceptibility to PRP was investigated by a standard disc diffusion test with or without pre-incubation of PRP with anti-hBD-2 antibody. SPSS statistical software was used for statistical analysis. PRP contains hBD-2 470 pg/10(9) platelets or 1786 pg/ml, respectively, (ELISA), which was confirmed by immunohistochemistry and Western Blot. In antimicrobial testing, PRP demonstrates effective inhibition of E. coli, B. megaterium, P. aeruginosa, E. faecalis and P. mirabilis. With this study we confirm the previously reported antimicrobial action of platelet concentrates i.e. PRP. In opposition to previously reported effects against gram positive bacteria our study focuses on gram negative and less common gram positive bacteria that do frequently cause clinical complications. We provide a possible molecular mechanism at least for E. coli and P. mirabilis for this effect by the detection of an antimicrobial peptide (hBD-2). This study may advocate the clinical use of PRP by highlighting a new aspect of platelet action.

Thrombocytes are effectors of the innate immune system releasing human beta defensin-3

BACKGROUND

Thrombocyte concentrate i.e. platelet-rich plasma (PRP) has become a popular adjunct for many surgical procedures. It is believed to improve bone and soft tissue healing. Recently antimicrobial effects of the autologous preparation were reported by several groups. In this study we investigated the antimicrobial effect of PRP against gram-negative microbes which frequently cause severe complications in orthopaedic trauma surgery.

METHODS

Platelet-rich plasma was produced from liquid preserved thrombocyte concentrates. ELISA, Western blot and immunohistochemistry were preformed to investigate the release and content of platelet concentrates. A radial diffusion assay was used to detect antimicrobial effects of PRP.

RESULTS

We detected the human beta defensin-3 in bactericidal concentrations in platelet preparations by ELISA, Western blot and immunohistochemistry. In antimicrobial testing we demonstrated effective inhibition of Escherichia coli (ATCC 11303), Bacterium megaterium (ATCC 14581), Klebsiella pneumoniae (ATCC 13883), Enterococcus faecalis (ATCC 29212) and Proteus mirabilis (ATCC21100).

CONCLUSION

With this study we demonstrate antimicrobial action of a popular adjunct for orthopaedic and trauma surgery against gram-positive and gram-negative bacteria. We have identified a possible mechanism of action via the secretion of HBD-3 as a first line defence in contaminated wounds and in elective application of PRP. This finding supports a broader spectrum of clinical indications for an autologous platelet preparation.

Bone regeneration and stem cells

This invited review covers research areas of central importance for orthopaedic and maxillofacial bone tissue repair, including normal fracture healing and healing problems, biomaterial scaffolds for tissue engineering, mesenchymal and foetal stem cells, effects of sex steroids on mesenchymal stem cells, use of platelet-rich plasma for tissue repair, osteogenesis and its molecular markers. A variety of cells in addition to stem cells, as well as advances in materials science to meet specific requirements for bone and soft tissue regeneration by addition of bioactive molecules, are discussed.