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

Impact of diabetes mellitus on surgical outcomes in sports medicine

Diabetes mellitus (DM) affects a significant proportion of the patients evaluated and treated by orthopedic surgeons who specialize in sports medicine. Sports-medicine-related conditions associated with DM include tendinopathy, adhesive capsulitis of the shoulder, and articular cartilage disease. This article reviews the current literature adressing the effect of DM on surgical outcomes in sports medicine. In general, patients with DM undergo operations more frequently and experience inferior surgical outcomes compared with patients without DM. Diabetes mellitus is associated with increased rates of complications from sports medicine procedures, such as infection, delayed healing, and failure of the operation. However, additional research is needed to determine the full impact of DM on patient outcomes in sports medicine. Surgeons should be cognizant of special considerations in the population of patients with DM and aim to tailor the surgical management of this growing patient population.

Adjunct methods of the standard diabetic foot ulceration therapy

The outcome of management of diabetic foot ulceration (DFU) is poor and insufficient. DFU therapy includes the standard management as debridement of the wound, revascularization procedures, off-loading of the ulcer and antibacterial actions, and supplementation of growth factors and cytokines, leading to stimulation of granulation, epidermization, and angiogenesis. The aim of the present review is to summarize the adjunct methods of the standard DFU therapy as hyperbaric oxygen therapy (HBOT), maggot therapy (MT), and platelet-rich plasma therapy (PRPT). The results of preclinical and clinical trials indicated that the methods may reduce time of therapy, short-term morbidity, and the risk of major amputation.

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.

Percutaneous autologous bone marrow injections for delayed or non-union of bones

PURPOSE

To evaluate 12 patients with delayed or nonunion of bones treated with bone marrow injections.

METHODS

6 men and 6 women aged 15 to 70 (mean, 45) years underwent bone marrow injections for delayed union (n=2) or atrophic non-union (n=10) of the ulna (n=6), femur (n=3), humerus (n=2), or metacarpal (n=1). Bone marrow was aspirated from the anterior iliac crest and injected to the delayed and non-union sites. Two injections were given for children and adolescents, and 3 for adults. The interval between the injections was 6 to 8 weeks. The amount of bone marrow injected was 30 to 40 ml for long bones and 20 ml for metacarpals.

RESULTS

Ten of the 12 delayed or non-union of bones healed after bone marrow injections. The mean time for callus formation was 5.8 (range, 3-10) weeks, for clinical union was 7 (range, 4-12) weeks, and for radiological union was 16 (range, 10-24) weeks.

CONCLUSION

Multiple injections of low-volume bone marrow can be used for treatment of delayed or non-union of bones.

The BB Wistar Rat as a Diabetic Model for Fracture Healing

The advent of improved glucose control with insulin and oral medications has allowed for the diabetic population to live longer and healthier lives. Unfortunately diabetes remains a worldwide epidemic with multiple health implications. Specifically, its affects upon fracture healing have been well studied and shown to have negative effects on bone mineral density, biomechanical integrity, and fracture healing. Multiple animal models have been used for research purposes to gain further insight into the effects and potential treatments of this disease process. The diabetic BB Wistar rat is one model that replicates a close homology to human type-1 diabetes and has been used as a fracture model to study the effects of diabetes on bone integrity and healing. In particular, the effects of tight glucose control, ultrasound therapy, platelet-rich plasma (PRP), platelet-derived growth factor (PDGF), bone morphogenetic protein 2 (BMP-2), and allograft bone incorporation have been studied extensively. We present a review of the literature using the BB Wistar rat to elucidate the implications of diabetes on fracture healing.

Systemic treatment with vanadium absorbed by Coprinus comatus promotes femoral fracture healing in streptozotocin-diabetic rats

The purpose of this study was to analyze the impact of vanadium absorbed by Coprinus comatus (VACC) on fracture healing in streptozotocin-diabetic rats. Forty-five male Wistar rats used were divided into three groups: normal rats (control), diabetic rats, and diabetic rats treated with VACC. A standardized fracture-healing model with a stable plate fixation was established for the rat femoral fracture. After a 4-week stable fixation, callus quality was assessed by microcomputerized tomography and histological and biomechanical examinations. In addition, bone samples were obtained to evaluate the content of mineral substances in bones. Compared with the diabetic group, vanadium treatment significantly increased bone mineral content and biomechanical strength and improved microstructural properties of the callus. The ultimate load was increased by 29.1 % (P<0.05), and the total bone volume of callus enhanced by 11.2 % (P<0.05) at 4 weeks post fracture. Vanadium also promoted callus bone formation, which caused a 35.5 % increase in the total area of callus. However, VACC did not accelerate the fracture repair process in histological analysis. In conclusion, the current study suggests that systemic treatment with vanadium could promote fracture healing in streptozotocin-diabetic rats.

Factors associated with nonunion, delayed union, and malunion in foot and ankle surgery in diabetic patients

The incidence of bone healing complications in diabetic patients is believed to be high after foot and ankle surgery. Although the association of hyperglycemia with bone healing complications has been well documented, little clinical information is available to show which diabetes-related comorbidities directly affect bone healing. Our goal was to better understand the risk factors associated with poor bone healing in the diabetic population through an exploratory, observational, retrospective, cohort study. To this end, 165 diabetic patients who had undergone arthrodesis, osteotomy, or fracture reduction were enrolled in the study to assess the risk factors associated with nonunion, delayed union, and malunion after elective and nonelective foot and/or ankle surgery. Bivariate analyses showed that a history of foot ulcer, peripheral neuropathy, and surgery duration were statistically significantly associated with bone healing complications. After adjusting for other covariates, only peripheral neuropathy, surgery duration, and hemoglobin A1c levels >7% were significantly associated statistically with bone healing complications. Of the risk factors we considered, peripheral neuropathy had the strongest association with bone healing complications.

Platelet-rich plasma for the treatment of lateral epicondylitis: sonographic assessment of tendon morphology and vascularity (pilot study)

OBJECTIVE

To investigate the efficacy of using contrast-enhanced ultrasound to assess the relationship of altered vascularity and tendon morphology following injection of platelet-rich plasma (PRP) for lateral epicondylitis.

MATERIALS AND METHODS

This study prospectively evaluated six patients who had a baseline ultrasound confirming tendinosis of the common extensor tendon. Patients received a single 3-ml PRP injection under ultrasound guidance. Grayscale images of the injected elbow were obtained at baseline and were repeated at 1 and 6 months after injection. DEFINITY® contrast was also injected after by 2 sets of wrist-extension exercises in order to obtain contrast-enhanced images of the elbow. Qualitative and quantitative analyses of the level of enhancement to the regions of interest were performed using off-line quantitative analysis software.

RESULTS

All patients had either moderate or severe common extensor tendinosis as determined on clinical examination and baseline imaging. Five patients demonstrated improved tendon morphology using ultrasound imaging 6 months after PRP injection (one patient was lost to follow-up). At baseline, there was evidence of increased vascularity at the myotendinous junction (MT) of the common extensor tendon when compared to its footprint (FP). There was a trend towards no change in FP vascularity between baseline and 6 months (p = 0.062) and between 1 and 6 months (p = 0.288). There was a trend for increased vascularity to the MT region from baseline to 6 months (p = 0.433) and from 1 to 6 months (p = 0.783).

CONCLUSIONS

Contrast-enhanced ultrasound provides a sensitive method the display alterations in vascularity in the common extensor tendon of the elbow. PRP therapy for lateral epicondylitis can improve extensor tendon morphology. Corresponding increased extensor tendon FP vascularity, however, was not seen. There is a trend for increased vascularity at the MT up to 6 months following PRP injection, based on limited pilot data.

Effect of autologous platelet-rich plasma on bone regeneration in mandibular fractures

OBJECTIVES

The aim of this study was to assess the effect of autologous platelet-rich plasma (PRP) on bone regeneration in mandibular fractures via a cone beam computed tomography (CBCT).

PATIENTS AND METHODS

Twenty-four patients having parasymphyseal fractures participated in this study. They were randomly divided into two equal groups. Group A was treated by two titanium miniplates and screws plus local application of activated PRP along the fracture line, whereas group B was treated by the same bone plates and screws without application of PRP. The patients were recalled at 1 week, 3 and 6 months after surgery for clinical assessment and measuring the bone density via CBCT at a region of interest (ROI) including the fracture line.

RESULTS

The mean values of the bone density measurements, in both groups, were higher at 3 and 6 months than 1 week after surgery. At 1 week after surgery, the values were 542 ± 93 HU and 515 ± 81 HU in group A and B, respectively. In group A, the mean value of bone density measurements was 728 ± 58 HU (range 620-796 HU) at 3 months after surgery and it was 1024 ± 188 HU (range 825-1490 HU) 6 months later. While in group B, the mean values of the bone density measurements at the ROI were 600 ± 78 HU (range 520-790 HU) and 756 ± 53 HU (range 710-890 HU) at 3 and 6 months after surgery, respectively. The increase in the bone density measurements at 3 and 6 months after surgery was statistically significant only in group A (P = 0.0002 and P = 0.0001, respectively).

CONCLUSIONS

It can be concluded that direct application of the PRP along the fracture lines may enhance the bone regeneration in mandibular fractures.

Efficacy of platelet-rich plasma combined with allograft bone in the management of displaced intra-articular calcaneal fractures: a prospective cohort study

To investigate whether platelet-rich plasma (PRP) when used with allograft bone improves the management outcome of displaced intra-articular calcaneal fractures. Over a 7-year period, all displaced type III calcaneal fractures admitted in our department (276 fractures in 254 patients) were randomly divided into three groups according to the plan of management: autograft alone (n = 101), allograft combined with PRP (n = 85), or allograft alone (n = 90). Radiographic imaging and three-dimensional computed tomography were used to assess the thalamic portion, Bohler's angle, the crucial angle of Gissane, and the height, width and length of the calcaneum. The American Orthopedic Foot and Ankle Society (AOFAS) ankle-hind-foot scoring system was used to evaluate the hind foot function at 12, 24, and 72 months postsurgery. At 12 months no significant difference existed in outcome amongst the treatment groups (p > 0.05). However, at 24 and 72 months the results of the autograft, and the allograft combined with PRP, were similar and both were significantly better than that of the allograft alone (p < 0.05). PRP augmented the favorable outcome of allografts in the management of displaced calcaneal fractures, and matched that of autograft used alone. The findings of this study thus support the clinical use of PRP in conjunction with allograft in the treatment of displaced intra-articular calcaneal fractures.

Use of platelet-leukocyte membrane in arthroscopic repair of large rotator cuff tears: a prospective randomized study

BACKGROUND

Arthroscopic rotator cuff repair generally provides satisfactory results including decreased shoulder pain and improved shoulder motion. Unfortunately, imaging studies demonstrate that the retear rate associated with the available arthroscopic techniques may be high. The purpose of this study was to evaluate the clinical and magnetic resonance imaging (MRI) results of arthroscopic rotator cuff repair with and without the use of platelet-leukocyte membrane in patients with a large posterosuperior rotator cuff tear.

METHODS

Eighty consecutive patients with a large full-thickness posterosuperior rotator cuff tear were enrolled. All tears were repaired using an arthroscopic single-row technique. Patients were randomized to treatment either with or without a platelet-leukocyte membrane inserted between the rotator cuff tendon and its footprint. In patients treated with this membrane, one membrane was utilized for each suture anchor. The primary outcomes were the difference between the preoperative and postoperative Constant scores and the repair integrity assessed by MRI according to the Sugaya classification. The secondary outcome was the difference between the preoperative and postoperative Simple Shoulder Test (SST) scores.

RESULTS

The only significant differences between the two groups involved the patient age and the preoperative and postoperative Constant scores; the differences in the Constant score were due to differences in the shoulder pain subscore. At a mean of thirteen months of follow-up, rotator cuff retears were observed only in the group of patients in whom the membrane had not been used, and a thin but intact tendon was observed more frequently in this group as well. The use of the membrane was associated with significantly better repair integrity (p = 0.04).

CONCLUSIONS

The use of the platelet-leukocyte membrane in the treatment of rotator cuff tears improved repair integrity compared with repair without membrane. However, the improvement in repair integrity was not associated with greater improvement in the functional outcome. In fact, the Constant scores of the two groups would have been similar if the shoulder pain component (which had differed preoperatively) had been excluded.

The role of platelet-rich plasma in inducing musculoskeletal tissue healing

BACKGROUND

Platelet-rich plasma [PRP] has received increasing interest across many musculoskeletal disciplines and has been widely applied clinically to stimulate tissue healing in numerous anatomical regions. The known actions of platelet-derived factors suggest that PRP may have significant potential in the treatment of pathological conditions of cartilage, tendon, ligament, and muscle.

PURPOSE

The aim of this manuscript is to review current literature regarding the biology of PRP and the efficacy of using PRP to augment healing of tendon ligament and muscle injuries, as well as early osteoarthritis.

METHODS

A comprehensive literature review of musculoskeletal applications of PRP was performed, including basic science and clinical studies such as randomized controlled trials, case controlled series, and case series.

RESULTS

The most compelling evidence to support the efficacy of PRP is for its application to tendon damage associated with lateral and medial epicondylitis. Although some promising studies have been reported supporting the use of PRP in osteoarthritis and ligament and muscle injuries, it currently remains unknown whether PRP effectively alters the progression of osteoarthritis or aids the healing of ligament and muscle tissues.

CONCLUSION

The rationale for the use of PRP to improve tissue healing is strong, but the efficacy for many musculoskeletal applications remains unproven. PRP has been shown to be a safe treatment. A number of questions regarding PRP remain unanswered, including the optimal concentration of platelets, what cell types should be present, the ideal frequency of application, or the optimal rehabilitation regimen for tissue repair and return to full function.

COMPARATIVE STUDY ON USE OF PLATELET-RICH PLASMA ALONE AND IN COMBINATION WITH ALPHA-TRICALCIUM PHOSPHATE CEMENT FOR BONE REPAIR IN RATS

Objectives: To evaluate the effect of alpha-tricalcium phosphate (α-TCP) cement combined with platelet-rich plasma (PRP) on osteogenesis, and to compare the results with use of PRP alone. Methods: A bilateral defect was produced in rat femurs and was filled with one of two types of treatments (PRP or α-TCP + PRP). The outcomes were evaluated after four and eight weeks. Radiographic images provided values for the lesion area, and histology (picrosirius staining) indicated the area of new bone formation. Results: The means relating to the lesion area of the α-TCP + PRP group (2.64 ± 2.07 and 1.91 ± 0.93 mm², after four and eight weeks, respectively) showed numerically better but non-significant results (p > 0.05) than those seen in the PRP group (5.59 mm 2 ± 2.69 and 3.23 ± 1.46 mm 2, after four and eight weeks, respectively). The mean new bone formation rates were 62.7% ± 12.1 and 79.01% ± 6.25 in the PRP group, and 73.3% ± 12.7 and 85.86% ± 10.45 in α-TCP + PRP group, after four and eight weeks, respectively (p > 0.05). Conclusion: The data from this study suggest that treatment with α-TCP cement combined with PRP does not show any significant difference in comparison with PRP alone. However, there is a possible early effect on bone regeneration when the two biomaterials are applied together.

Comparison of the acute inflammatory response of two commercial platelet-rich plasma systems in healthy rabbit tendons

BACKGROUND

Numerous studies have shown platelet-rich plasma (PRP) preparations differ with respect to the inclusion of certain blood components, which may affect the host's cellular response.

HYPOTHESIS

This study evaluated the inflammatory effect of Biomet GPS III leukocyte-rich PRP (LR-PRP) versus MTF Cascade leukocyte-poor PRP (LP-PRP) after intratendinous injection in an animal model. The authors anticipated that LR-PRP would incite a greater acute inflammatory response than LP-PRP.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 17 skeletally mature New Zealand White rabbits were tested. In all cases, healthy patellar tendons were treated. In the control animals, one patellar tendon was injected with 2 mL autologous whole blood, and the other was injected with 2 mL sterile saline. Seven total tendons were injected with whole blood, and 7 tendons were injected with saline. In the experimental animals, one patellar tendon was injected with 2 mL LR-PRP, and the other was injected with 2 mL LP-PRP. Ten tendons were injected with LR-PRP, and 10 tendons were injected with LP-PRP. Animals were euthanized at 5 or 14 days after injection. Tendons were harvested and stained using hematoxylin and eosin and scored semi-quantitatively for total white blood cells (WBCs), mononuclear cells (macrophages and lymphocytes), polymorphonuclear cells (PMNs), vascularity, fiber structure, and fibrosis.

RESULTS

At 5 days after injection, tendons treated with LR-PRP had significantly greater overall tendon scores (6.3 ± 1.79 vs 1.8 ± 1.64, P = .012), as well as mean scores for fiber structure (1.4 ± 0.22 vs 0.50 ± 0.50, P = .012), denoting disrupted composition, total WBCs (1.1 ± 0.89 vs 0.10 ± 0.22, P = .014), mononuclear cells (macrophages and lymphocytes) (0.80 ± 0.45 vs 0.10 ± 0.22, P = .014), vascularity (1.7 ± 0.27 vs 0.80 ± 0.16, P = .008), and fibrosis (1.0 ± 0.35 vs 0.3 ± 0.45, P = .037) compared with tendons treated with LP-PRP. Otherwise, there were no significant differences in mononuclear cells (P = .590), PMN cells (P = 1.00), total WBCs (P = .811), vascularity (P = .650), or total tendon score (P = .596) in any of the treatment groups at 14 days.

CONCLUSION

Compared with leukocyte-poor Cascade PRP, leukocyte-rich GPS III PRP causes a significantly greater acute inflammatory response at 5 days after injection. There is no significant difference in the inflammatory response or cellularity regardless of the injection type at 14 days after intratendinous injection.

CLINICAL RELEVANCE

Platelet-rich plasma injections are frequently prepared using commercial systems and are administered for clinical treatment of chronic tendinopathy. It is important to characterize the cellular responses elucidated by different injection preparations to further understand their effect on tissue healing and aid clinical decision making. Future investigations are necessary to apply these findings to the clinical setting.

Is the expression of Transforming Growth Factor-Beta1 after fracture of long bones solely influenced by the healing process?

PURPOSE

Circulating TGF-β1 levels were found to be a predictor of delayed bone healing and non-union. We therefore aimed to investigate some factors that can influence the expression of TGF-β1. The correlation between the expression of TGF-β1 and the different socio-demographic parameters was analysed.

METHODS

Fifty-one patients with long bone fractures were included in the study and divided into different groups according to their age, gender, cigarette smoking status, diabetes mellitus and regular alcohol intake. TGF-β1 levels were analysed in patient's serum and different groups were retrospectively compared.

RESULTS

Significantly lower TFG-β1 serum concentrations were observed in non-smokers compared to smokers at week 8 after surgery. Significantly higher concentrations were found in male patients compared to females at week 24. Younger patients had significantly higher concentrations at week 24 after surgery compared to older patients. Concentrations were significantly higher in patients without diabetes compared to those with diabetes at six weeks after surgery. Patients with chronic alcohol abuse had significantly higher concentrations compared to those patients without chronic alcohol abuse.

CONCLUSION

TGF-β1 serum concentrations vary depending upon smoking status, age, gender, diabetes mellitus and chronic alcohol abuse at different times and therefore do not seem to be a reliable predictive marker as a single-point-in-time measurement for fracture healing.

Platelet activation: ultrastructure and morphometry in platelet-rich plasma of horses

This study was conducted to investigate the activation ability of the platelet-rich plasma (PRP) by pharmacological agents, as well as to verify the need or not of this activation for therapeutic use. The PRP was obtained from four healthy crossbred geldings aged 13 to 16 years (15±1years), and was processed for observation and quantification of the platelet morphology by using the transmission electron microscopy. All PRP samples were activated with 10% calcium chloride (CaCl2) solution, pure bovine thrombin or associated with CaCl2. The control (pure PRP) was not pharmacologically activated. In the pure PRP samples, 49% of the platelets were classified as state of activation uncertain, 41% as resting, 9% as fully activated and 1% as irreversibly damaged. Treatment with 10% CaCl2 provided a distribution of 54% platelets in state of activation uncertain, 24% as fully activated, 20% as resting, and 2% as irreversibly damaged. The platelet morphology of the bovine thrombin treated samples did not fit into classification adopted, as showing irregular shape with emission of large filamentous pseudopods, appearance of ruptured and whole granules in the remaining cytoplasm and extracellular environment. There was effect of the treatment on the platelet morphology (P=0.03). The 10% CaCl2 is an adequate platelet-activating agent. However, in cases the use of PRP under its liquid form is necessary, the use of pure PRP is recommended, since besides presenting an adequate percentage of fully activated platelets it also has significant amount of the resting type, which can be activated by substances found in the injured tissue.

Development of mesenchymal stem cell-implant complexes by cultured cells sheet enhances osseointegration in type 2 diabetic rat model

This study investigated the hypothesis that a mesenchymal stem cells (MSC)-implant complex could be used in type 2 diabetic rats. Diabetes was modeled with type 2 diabetic rats induced by high fat diet with low dose streptozotocin (STZ) injected intraperitoneally. MSC sheets were harvested from culture flasks, wrapped around implants to construct the complexes, and then cultured in an osteogenic medium. The layered cell sheets integrated well with the implants and remained viable, with small mineralized nodules visible on the implant surfaces after culturing. The MSC-implant complexes were inserted into the right tibiae of the diabetic rats. Titanium implants served as controls. After four and eight weeks of healing, the tibiae were observed via MicroCT and harvested for histological examination. For the MSC-implant complexes, MicroCT analysis showed that bone volume ratio and trabecular thickness increased significantly (p<0.05), and trabecular separation decreased significantly (p<0.05) compared to the titanium implants in diabetic rats. Histological examination revealed a greater amount of new bone tissue forming around the MSC-implant complexes and a higher bone implant contact (BIC) rate than the titanium implants. These findings demonstrate that MSC-implant complexes possess osteogenic abilities and can be used in diabetic rats to improve the BIC rate. Thus, MSC-implant complexes provide a novel tissue engineering approach that promotes osseous healing and may potentially be useful in the treatment of diabetic patients.

Review: The diabetic bone: a cellular and molecular perspective

With the increasing worldwide prevalence of diabetes the resulting complications, their consequences and treatment will lead to a greater social and financial burden on society. One of the many organs to be affected is bone. Loss of bone is observed in type 1 diabetes, in extreme cases mirroring osteoporosis, thus a greater risk of fracture. In the case of type 2 diabetes, both a loss and an increase of bone has been observed, although in both cases the quality of the bone overall was poorer, again leading to a greater risk of fracture. Once a fracture has occurred, healing is delayed in diabetes, including nonunion. The reasons leading to such changes in the state of the bone and fracture healing in diabetes is under investigation, including at the cellular and the molecular levels. In comparison with our knowledge of events in normal bone homeostasis and fracture healing, that for diabetes is much more limited, particularly in patients. However, progress is being made, especially with the use of animal models for both diabetes types. Identifying the molecular and cellular changes in the bone in diabetes and understanding how they arise will allow for targeted intervention to improve diabetic bone, thus helping to counter conditions such as Charcot foot as well as preventing fracture and accelerating healing when a fracture does occur.

Comparison of growth factor and platelet concentration from commercial platelet-rich plasma separation systems

BACKGROUND

Clinical studies claim that platelet-rich plasma (PRP) shortens recovery times because of its high concentration of growth factors that may enhance the tissue repair process. Most of these studies obtained PRP using different separation systems, and few analyzed the content of the PRP used as treatment.

PURPOSE

This study characterized the composition of single-donor PRP produced by 3 commercially available PRP separation systems.

STUDY DESIGN

Controlled laboratory study.

METHODS

Five healthy humans donated 100 mL of blood, which was processed to produce PRP using 3 PRP concentration systems (MTF Cascade, Arteriocyte Magellan, Biomet GPS III). Platelet, white blood cell (WBC), red blood cell, and fibrinogen concentrations were analyzed by automated systems in a clinical laboratory, whereas ELISA determined the concentrations of platelet-derived growth factor αβ and ββ (PDGF-αβ, PDGF-ββ), transforming growth factor β1 (TGF-β1), and vascular endothelial growth factor (VEGF).

RESULTS

There was no significant difference in mean PRP platelet, red blood cell, active TGF-β1, or fibrinogen concentrations among PRP separation systems. There was a significant difference in platelet capture efficiency. The highest platelet capture efficiency was obtained with Cascade, which was comparable with Magellan but significantly higher than GPS III. There was a significant difference among all systems in the concentrations of WBC, PDGF-αβ, PDGF-ββ, and VEGF. The Cascade system concentrated leukocyte-poor PRP, compared with leukocyte-rich PRP from the GPS III and Magellan systems.

CONCLUSION

The GPS III and Magellan concentrate leukocyte-rich PRP, which results in increased concentrations of WBCs, PDGF-αβ, PDGF-ββ, and VEGF as compared with the leukocyte-poor PRP from Cascade. Overall, there was no significant difference among systems in the platelet concentration, red blood cell, active TGF-β1, or fibrinogen levels.

CLINICAL RELEVANCE

Products from commercially available PRP separation systems produce differing concentrations of growth factors and WBCs. Further research is necessary to determine the clinical relevance of these findings.

The effects of low-intensity pulsed ultrasound upon diabetic fracture healing

In the United States, over 17 million people are diagnosed with type 1 diabetes mellitus (DM) with its inherent morbidity of delayed bone healing and nonunion. Recent studies demonstrate the utility of pulsed low-intensity ultrasound (LIPUS) to facilitate fracture healing. The current study evaluated the effects of daily application of LIPUS on mid-diaphyseal femoral fracture growth factor expression, cartilage formation, and neovascularization in DM and non-DM BB Wistar rats. Polymerase chain reaction (PCR) and ELISA assays were used to measure and quantify growth factor expression. Histomorphometry assessed cartilage formation while immunohistochemical staining for PECAM evaluated neovascularization at the fracture site. In accordance with previous studies, LIPUS was shown to increase growth factor expression and cartilage formation. Our study also demonstrated an increase in fracture callus neovascularization with the addition of LIPUS. The DM group showed impaired growth factor expression, cartilage formation, and neovascularization. However, the addition of LIPUS significantly increased all parameters so that the DM group resembled that of the non-DM group. These findings suggest a potential role of LIPUS as an adjunct for DM fracture treatment.

Current concepts for the use of platelet-rich plasma in the foot and ankle

Platelet-rich plasma (PRP) injections have been used and studied since the 1970s. Its use has become more popularized over the last several years in the treatment of foot and ankle injuries. Platelets are a normal product found in the clotting cascade and inflammatory process of healing. They produce granules that release growth factors that promote healing. PRP works by increasing the concentration of platelets, thereby increasing the concentration of growth factors and increasing healing potential. PRP has an advantage over many tissue engineering products in that it is autologous. It has been studied and used for the treatment of tendon injuries, chronic wounds, ligamentous injuries, cartilage injuries, muscle injuries, and bone augmentation. The results from in vitro and in vivo studies in foot and ankle injuries are promising. The applications for treatment in the foot and ankle may be broader than once thought.

Ankle injuries and fractures in the obese patient

Ankle fractures are a common orthopedic injury. Certain ankle injuries have been associated with patient demographics such as obesity and smoking. Obese patients are more prone to severe ankle injuries. Naturally, these injuries affect the lower extremity mobility significantly, which itself is a risk factor for obesity. Although obese patients have increased complications across the board, there are specific techniques that can be used to assure the best possible outcome. The perioperative, surgical, and postoperative considerations as well as the outcomes are discussed in this article.

Effect of shock wave treatment on platelet-rich plasma added to osteoblast cultures

The aim of this study was to verify the effects on osteoblast cultures of adding a platelet-rich plasma (PRP) concentrate pretreated with 500 shock wave (SW) at an energy flow density of 0.17 mJ/mm(2), emitted by an electromagnetic generator Minilith SL1 (STORZ, Germany), reproducing the conditions of our previous study in which we apply SW directly on osteoblasts. Real-time PCR showed that in osteoblast cultures with added PRP pretreated with SW, there was an increased expression at 48 h of insulin-like growth factor binding protein 3 (IGFBP-3) and runt-related transcription factor 2 (RUNX2) and at 72 h, of collagen type I, osteocalcin, insulin-like growth factor 1 (IGF-1) as well as IGFBP-3. Western blotting confirmed the increased protein synthesis of IGFBP-3. This experience suggests that extracorporeal shock wave treatment (ESWT) should stimulate osteogenesis also by indirect platelets-mediated network. It therefore seems possible that combining the two methods, ESWT and bioengineering procedures to infiltrate PRP and growth factors, could be a successful approach.

Comparison between Platelet-Rich Plasma and Autologous Iliac Grafts for Tibial Osteotomy

OBJECTIVE

Platelet-rich plasma (PRP) has the capacity to improve the bone-healing process. The aim of this pilot study was to investigate the occurrence of bone healing and the time taken to achieve this in patients submitted to medial opening wedge high tibial osteotomy (MOWHTO), comparing platelet-rich plasma with bone marrow aspirate to autologous iliac graft.

DESIGN

Twenty-five patients who underwent tibial osteotomy were randomly divided into 2 groups: a control group, which received autologous iliac grafts (14 patients), and a study group, which received a compound of PRP and bone marrow aspirate (11 patients).

RESULTS

The bone-healing rates achieved were 100% in the control group and 91% in the study group. There was no difference in the time taken to achieve bone healing between the groups.

CONCLUSIONS

The use of a combination of PRP and bone marrow aspirate, as a bone substitute, did not demonstrate any advantage over the use of an autologous iliac graft in MOWHTO.

The control of fracture healing and its therapeutic targeting: improving upon nature

Fracture repair is a complex process involving timed cellular recruitment, gene expression, and synthesis of compounds that regenerate native tissue to restore the mechanical integrity, and thus function of injured bone. While the majority of fractures heal without complication, this takes time and a subset of patients ( approximately 10%) experience healing delays, extending their morbidity and treatment costs. Consequently, there is a need for efficacious therapeutics for the intervention of fracture healing. Recent studies into the molecular control of fracture repair and advances in the understanding of the skeleton as a whole have resulted in the identification of numerous novel targets and compounds for such intervention. These include traditional agents such bone morphogenetic proteins and other growth factors, but also relatively newer compounds such as parathyroid hormone and modulators of the Wnt signaling pathway. These agents, along with others, are discussed in the current article in terms of their investigative status and potential for clinical implementation. Hopefully, these agents, as well as others yet to be discovered, will demonstrate sufficient clinical utility for successful intervention of fracture healing. This may have significant implications for the duration of morbidity and costs associated with traumatic bone fractures.

Platelet rich plasma injection grafts for musculoskeletal injuries: a review

In Europe and the United States, there is an increasing prevalence of the use of autologous blood products to facilitate healing in a variety of applications. Recently, we have learned more about specific growth factors, which play a crucial role in the healing process. With that knowledge there is abundant enthusiasm in the application of concentrated platelets, which release a supra-maximal quantity of these growth factors to stimulate recovery in non-healing injuries. For 20 years, the application of autologous PRP has been safely used and documented in many fields including; orthopedics, sports medicine, dentistry, ENT, neurosurgery, ophthalmology, urology, wound healing, cosmetic, cardiothoracic, and maxillofacial surgery. This article introduces the reader to PRP therapy and reviews the current literature on this emerging treatment modality. In summary, PRP provides a promising alternative to surgery by promoting safe and natural healing. However, there are few controlled trials, and mostly anecdotal or case reports. Additionally the sample sizes are frequently small, limiting the generalization of the findings. Recently, there is emerging literature on the beneficial effects of PRP for chronic non-healing tendon injuries including lateral epicondylitis and plantar fasciitis and cartilage degeneration (Mishra and Pavelko, The American Journal of Sports Medicine 10(10):1–5, 2006; Barrett and Erredge, Podiatry Today 17:37–42, 2004). However, as clinical use increases, more controlled studies are needed to further understand this treatment.

Background and rationale of platelet gel in orthopaedic surgery

Autologous platelet gel, which is usually prepared by adding thrombin and calcium to a platelet concentrate, is used to accelerate bone repair as a possible alternative to recombinant growth factors (GF), through the osteogenic GF released from alpha-granules. The advantages of platelet gel lie in its mimicking the GF effects of the physiological bone healing and regenerative processes, in addition to a relatively simple and low cost technique. Moreover, if autologous platelet gel is used, immunological reactions are avoided. In in vitro systems, platelet gel stimulated osteogenic differentiation of bone marrow stromal cells, while it inhibited complete osteoclast differentiation and activation. Moreover, platelet gel favoured endothelial cell proliferation and expression of pro-osteogenic functions. In experimental animals and in clinical application, the efficacy of platelet gel was increased by the combination with bone allografts, acting as scaffolds, and with bone marrow stromal cells.

Absence of beta3 integrin accelerates early skeletal repair

Integrins are heterodimeric transmembrane proteins that mediate cell-matrix interactions and modulate cell behavior. Beta3 subunit is a component of alphaIIbeta3 and alphaVbeta3 integrins. In this study, we first determined that beta3 transcripts are expressed by cells within fracture calluses at 7 and 10 days after injury in a mouse model. We then analyzed fracture healing in mice deficient of beta3 integrin with molecular, histomorphometric, and biomechanical techniques. We found that lack of beta3 integrin results in an extended bleeding time and leads to more bone formation and accelerated cartilage maturation at 7 days after injury. However, beta3 deficiency does not appear to affect later fracture healing. At days 14 and 21, histological appearance or biomechanical properties of fracture calluses are similar between wild type and mutant mice. We also found that altered fracture healing in beta3-null mice is not associated with accelerated angiogenesis, because no significant difference of length density and surface density of blood vessels in fracture limbs was detected at 3 days after injury between wild type and beta3-null mice. In conclusion, our findings demonstrate that beta3 integrin plays an important role during early fracture healing. Further research is required to determine the underlying mechanisms.

Platelet-rich plasma: from basic science to clinical applications

Platelet-rich plasma (PRP) has been utilized in surgery for 2 decades; there has been a recent interest in the use of PRP for the treatment of sports-related injuries. PRP contains growth factors and bioactive proteins that influence the healing of tendon, ligament, muscle, and bone. This article examines the basic science of PRP, and it describes the current clinical applications in sports medicine. This study reviews and evaluates the human studies that have been published in the orthopaedic surgery and sports medicine literature. The use of PRP in amateur and professional sports is reviewed, and the regulation of PRP by antidoping agencies is discussed.

Bone and wound healing augmentation with platelet-rich plasma

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

The biology of platelet-rich plasma and its application in trauma and orthopaedic surgery: a review of the literature

Although mechanical stabilisation has been a hallmark of orthopaedic surgical management, orthobiologics are now playing an increasing role. Platelet-rich plasma (PRP) is a volume of plasma fraction of autologous blood having platelet concentrations above baseline. The platelet alpha granules are rich in growth factors that play an essential role in tissue healing, such as transforming growth factor-beta, vascular endothelial growth factor, and platelet-derived growth factor. PRP is used in various surgical fields to enhance bone and soft-tissue healing by placing supraphysiological concentrations of autologous platelets at the site of tissue damage. The easily obtainable PRP and its possible beneficial outcome hold promise for new regenerative treatment approaches. The aim of this literature review was to describe the bioactivities of PRP, to elucidate the different techniques for PRP preparation, to review animal and human studies, to evaluate the evidence regarding the use of PRP in trauma and orthopaedic surgery, to clarify risks, and to provide guidance for future research.

Recombinant human platelet-derived growth factor BB (rhPDGF-BB) and beta-tricalcium phosphate/collagen matrix enhance fracture healing in a diabetic rat model

Diabetes mellitus is a common systemic disease that has been associated with poor fracture healing outcomes. The mechanism through which diabetes impairs bone regeneration is unknown. One possible mechanism may be related to either decreased or uncoordinated release of local growth factors at the fracture site. Indeed, previous studies have found reduced platelet-derived growth factor (PDGF) levels in the fracture callus of diabetic rats, suggesting that local application of PDGF may overcome the negative effects of diabetes and promote fracture healing. To test this hypothesis, low (22 microg) and high (75 ug) doses of recombinant human PDGF-BB (rhPDGF-BB) were applied directly to femur fracture sites in BB Wistar diabetic rats that were then compared to untreated or vehicle-treated animals. rhPDGF-BB treatment significantly increased early callus cell proliferation compared to that in control specimens. Low dose rhPDGF-BB treatment significantly increased callus peak torque values (p < 0.05) at 8 weeks after fracture as compared to controls. High dose rhPDGF-BB treatment increased callus bone area at 12 weeks postfracture. These data indicate that rhPDGF-BB treatment ameliorates the effects of diabetes on fracture healing by promoting early cellular proliferation that ultimately leads to more bone formation. Local application of rhPDGF-BB may be a new therapeutic approach to treat diabetes-impaired fracture healing.

Activated platelets increase fibrinolysis of mesenchymal progenitor cells

Bone regeneration is initiated by the formation of a blood clot. Activated platelets within this fibrin-rich matrix release signaling molecules that can attract mesenchymal progenitor cells. To gain insight into the cellular mechanism by which activated platelets can support the immigration of mesenchymal progenitors, we have tested the hypothesis that platelet-released signaling molecules increase the capacity of bone marrow stromal cells (BMSC) to activate plasminogen. We report herein that platelet-released supernatants (PRS) elevate total urokinase-type plasminogen activator (uPA) and total plasminogen activator inhibitor-1 (PAI-1) levels in BMSC, as assessed by immunoassay. Quantitative polymerase chain reaction showed an upregulation of uPA, uPA receptor, and PAI-1. Zymography and kinetic analysis based on casein hydrolysis revealed enhanced activity of cell-associated uPA upon exposure of BMSC to PRS. Inhibiting c-Jun N-terminal kinase (JNK) and phosphatidylinositol 3-kinase (PI3K) signaling reduced uPA production and decreased plasminogen activation. Corresponding Western blot analysis showed increased phosphorylation of JNK and AKT in BMSC treated with PRS. These results suggest that activated platelets can enhance the plasminogen activation capacity of mesenchymal progenitors through the stimulation of uPA production, requiring JNK and PI3K/AKT signaling. By this mechanism platelets may contribute to the organization of the blood clot during bone regeneration.

rhBMP-2 enhances the bone healing response in a diabetic rat segmental defect model

OBJECTIVE

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to enhance new bone formation in fracture and bone defect models in both normal and diabetic rats. Effects of rhBMP-2 in a segmental femoral defect model in diabetes mellitus (DM) BB Wistar rats have not been reported.

METHODS

Collagen sponge soaked with either buffer or rhBMP-2 was inserted in a mid-diaphyseal 3.0-mm defect fixed with polyimide plate and stainless steel screws, in 62 DM BB Wistar rats. Progress of new bone formation in the defect was monitored with serial radiographs every 2 weeks. Histomorphometric analysis of the new bone formation was done on undecalcified sections of the extracted femurs at 3 and 6 weeks post surgery. Further analysis of the new bone was done by assessment of neoangiogenesis using immunohistochemical staining for Platelet endothelial cell adhesion molecule-1. Mechanical testing was performed at 9 weeks to assess the new bone with respect to 4 different parameters of mechanical and structural properties of bone.

RESULTS

Radiographs assessed over a 6-point grading system showed statistically significant improvement in scores in rhBMP-2-treated rats at 6 weeks (P < 0.001). Histomorphometric analysis showed statistically significant increase in area of new bone formation between rats treated with rhBMP-2 compared with buffer at both 3 and 6 weeks (P < 0.001). On Platelet endothelial cell adhesion molecule-1 staining at 3 weeks, the mean number of vessels in rhBMP-2-treated DM rats was 12.76 +/- 5.43/mm(2) compared with 4.49 +/- 1.89/mm(2) in buffer treated DM rats (P = 0.034). On mechanical testing, all 4 DM/buffer rats had nonunion. In DM/rhBMP-2 rats, the torque to failure and torsional rigidity values were 393.57 +/- 233.3 (P < 0.03) and 29,711 +/- 6224 (P < 0.002), respectively.

CONCLUSIONS

Clearly, although DM has a known impact on osseous healing, its negative effects are ameliorated with the application of the rhBMP-2-collagen carrier and demonstrates the potential clinical role of this adjunct in the clinical arena.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nonunions treated with autologous preparation rich in growth factors

OBJECTIVES

To evaluate the clinical safety and efficacy of using a biologic technology known as preparation rich in growth factors (PRGF) for the treatment of nonhypertrophic nonunion.

DESIGN

The design of the study was a retrospective case series.

SETTING

The private practice was in 2 centers.

PATIENTS

There were 15 patients with a total of 16 aseptic nonunions, 12 diaphyseal and 4 supracondylar, diagnosed as nonhypertrophic. The mean time since prior surgical treatment was 21 months (9-46 months).

INTERVENTION

Supracondylar and diaphyseal nonunions followed surgical fixation with condylar plating or intramedullary nailing, whereas a composite biomaterial created by mixing PRGF with bone allograft was applied. The area was then covered with autologous fibrin membranes. Stable nonunions were treated with repeated percutaneous injections of PRGF; this minimally invasive procedure was also applied if delayed healing was suspected after surgical treatment.

MAIN OUTCOME MEASUREMENTS

Radiographic union using radiographic views was taken in 2 planes. Clinical outcome evaluated pain, motion at the fracture site upon manual stress testing, and recovery of range of motion.

RESULTS

All nonunions treated operatively healed after a single procedure, even though additional PRGF had to be injected in 2 patients. Two of 3 stable nonunions achieved healing only after repeated percutaneous PRGF injections. The mean time from surgery and/or PRGF application to union was 4.9 months (2-8 months). Complications associated with the described procedure were not observed.

CONCLUSION

This study, although uncontrolled, shows that PRGF technology is clinically safe and can enhance the healing of nonhypertrophic nonunions.

THE USE OF PLATELET RICH PLASMA WITH BONE MARROW ASPIRATE IN PUDDU TIBIAL OSTEOTOMY

Objective: The present study was performed in order to evaluate the use of platelet rich plasma associated to bone marrow aspirate, substituting autologous iliac bone graft in medial opening wedge osteotomy (OWHTO). Methods: Twenty-five patients were submitted to tibial opening wedge osteotomy, being divided into two groups. Iliac group: 14 patients submitted to OWHTO, using autologous iliac bone graft to fill the gap. PRP group: 11 patients using platelet rich plasma associated to bone marrow aspirate to fill the gap. We evaluated bleeding (hemoglobin and hematocrit levels) and pain (visual analogic scale-VAS), then we compared the groups regarding these variables. Results: Differences between the groups were not found regarding hemoglobin levels (p=0.820) and hematocrit levels (p=0.323). The groups were not different regarding pain measured with VAS (p=0.538). Conclusion: The use of platelet rich plasma associated to bone marrow aspirate in medial opening wedge osteotomy did not offer advantages over autologous iliac bone graft regarding bleeding and pain.

Platelet-rich concentrate supports human mesenchymal stem cell proliferation, bone morphogenetic protein-2 messenger RNA expression, alkaline phosphatase activity, and bone formation in vitro: a mode of action to enhance bone repair

OBJECTIVE

Platelet-rich concentrate (PRC) is an autologous growth factor preparation that is in routine use for orthopaedic and maxillofacial surgery. However, there are little data available describing the cellular and molecular mechanisms by which PRC enhances the healing response in an osseous environment. The aim of this study was to identify cellular and molecular events that are modulated in human mesenchymal stem cells (hMSCs) in response to exposure to human PRC generated by a novel filtration-based device (CAPTION, Smith & Nephew Inc).

METHODS

PRC and serum were prepared from blood donated by 11 volunteers. Growth factor content and release from PRC were determined by enzyme-linked immunosorbent assay. Cell proliferation was quantified by DNA content and osteoblastic differentiation by alkaline phosphatase expression and mineralized nodule formation. Real-time reverse transcription-polymerase chain reaction analysis was used to determine the early molecular pathways regulated in hMSCs by PRC.

RESULTS

The results obtained confirm previous in vitro and in vivo observations demonstrating that PRC enhances hMSC proliferation. Furthermore, our data suggest that when added as a clot, PRC induces an earlier onset of proliferation compared with serum without leading to cell overgrowth and the inhibition of cell differentiation. At the molecular level, PRC treatment stimulated a transient enhancement of bone morphogenetic protein-2 messenger RNA that peaked after 12 hours and induced an earlier and a sustained increase in the key osteogenic transcription factor RUNX2. By 3 days of treatment, PRC enhanced alkaline phosphatase activity more than 2-fold compared with donor-matched serum, and at 23 days, the increase in osteoblastic commitment translated to enhanced calcified matrix deposition.

CONCLUSIONS

Taken together, the data presented here suggest that treatment of hMSC with clotted PRC, in an osteoinductive environment, enhances osteoblastic commitment and bone formation. Furthermore, these data indicate that the enhanced osteogenesis seen in the presence of PRC cannot be explained solely by enhanced cell proliferation, suggesting that PRC modulates a number of cell and molecular pathways to promote bone formation.

The effect of platelet-rich plasma on healing in critical-size long-bone defects

The role of platelet-rich plasma (PRP) as a promoter of bone healing remains controversial. The hypothesis investigated was that PRP improves bone healing of a critical-size diaphyseal radius defect in a rabbit model. The bone defect was filled with a high-surface ceramic scaffold, calcium-deficient hydroxyapatite (CDHA), with the addition of allogenic PRP, mesenchymal stem cells (MSC) or both. PRP yielded better bone formation than the empty CDHA scaffold as determined by both histology and micro-computer tomography (p<0.05) after 16 weeks, whereas no difference was observed on biomechanical testing. Similar behavior was found in samples with MSC; however, the combination of MSC and PRP did not further improve bone healing. Furthermore, the resorption of CDHA was improved by the addition of PRP, MSC and MSC/PRP, but there were no differences between the groups. The areas of bone formation were greater in areas adjacent to the bone resection areas and towards the intact ulna. In conclusion, PRP improves bone healing in a diaphyseal rabbit model on CDHA and the combination of CDHA. This study supports the allogenic use of PRP for bone healing as an off-the-shelf therapy.