Tendon healing and platelet-rich plasma therapies

Ultrasound-Guided Subfascial Platelet-Rich Plasma Injections Versus Enthesis Needling for Greater Trochanteric Pain Syndrome: A Randomized Controlled Trial

Background

Greater trochanteric pain syndrome (GTPS) is characterized by gluteal enthesopathy involving the peritrochanteric space and associated with chronic pain and functional impairment. A corticosteroid injection in the trochanteric bursa is the usual palliative treatment for pain. However, it is important to investigate treatment options that will relieve pain in the peritrochanteric space.

Purpose

To compare the clinical efficacy of subfascial platelet-rich plasma (PRP) injection and enthesis needling for GTPS.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

A total of 92 patients (90% women; mean age, 55 years old; mean body mass index, 25.3 kg/m2) were randomly divided into a subfascial PRP injection group and an enthesis needling group. Descriptive data and radiographic measurements of the pelvis-including leg-length difference, pelvic width difference, and pelvic trochanteric index-were recorded. The primary outcome measures were the Hip Outcome Score (HOS) activities of daily living (HOS-ADL) and sports-specific (HOS-SS) subscales and the visual analog scale for pain at 3, 6, and 12 months posttreatment. In addition, we evaluated the presence or absence of ultrasound characteristics (fascia nodules, trochanteric bursa distension, and calcium deposits) over time in response to treatment.

Results

Baseline demographic and radiological characteristics were similar between the groups. The PRP group saw significantly greater improvement from baseline to 12 months posttreatment on the HOS-SS subscore compared with the needling group (32.09 [95% CI, 28.99-40.20] vs 20.52 [95% CI, 11.99-29.05]; P = .048). At 3 months, 60% of patients in the PRP group versus 33.3% in the needling group had a reduction in pain compared with a baseline of >20% (P = .040). After subfascial PRP injection, fewer patients had a fascia nodule over the trochanter and/or bursa distension (P = .006 and P = .004, respectively). The pelvic trochanteric index was predictive of HOS-ADL and HOS-SS outcomes (P = .011 and P = .022, respectively). The interaction between treatment modality and fascia nodule influenced HOS-ADL and HOS-SS outcomes (P = .021 and P = .023) as well as the interactions of treatment modality, fascia nodules, and calcifications (P = .027).

Conclusion

Both subfascial PRP injection and enthesis needling resulted in clinical improvements, but the improvement in the HOS-SS was greater in the PRP group.

Registration

NCT04231357 (ClinicalTrials.gov identifier).

Effect of platelet-rich plasma in Achilles tendon allograft in rabbits

BACKGROUND

Achilles tendon is composed of dense connective tissue and is one of the largest tendons in the body. In veterinary medicine, acute ruptures are associated with impact injury or sharp trauma. Healing of the ruptured tendon is challenging because of poor blood and nerve supply as well as the residual cell population. Platelet-rich plasma (PRP) contains numerous bioactive agents and growth factors and has been utilized to promote healing in bone, soft tissue, and tendons.

OBJECTIVE

The purpose of this study was to evaluate the healing effect of PRP injected into the surrounding fascia of the Achilles tendon after allograft in rabbits.

METHODS

Donor rabbits (n = 8) were anesthetized and 16 lateral gastrocnemius tendons were fully transected bilaterally. Transected tendons were decellularized and stored at -80°C prior to allograft. The allograft was placed on the partially transected medial gastrocnemius tendon in the left hindlimb of 16 rabbits. The allograft PRP group (n = 8) had 0.3 mL of PRP administered in the tendon and the allograft control group (n = 8) did not receive any treatment. After 8 weeks, rabbits were euthanatized and allograft tendons were transected for macroscopic, biomechanical, and histological assessment.

RESULTS

The allograft PRP group exhibited superior macroscopic assessment scores, greater tensile strength, and a histologically enhanced healing process compared to those in the allograft control group.

CONCLUSIONS

Our results suggest administration of PRP on an allograft tendon has a positive effect on the healing process in a ruptured Achilles tendon.

The mechanisms and functions of TGF-β1 in tendon healing

Tendon injury accounts for 30% of musculoskeletal diseases and often leads to disability, pain, healthcare cost, and lost productivity. Following injury to tendon, tendon healing proceeds via three overlapping healing processes. However, due to the structural defects of the tendon itself, the tendon healing process is characterized by the formation of excessive fibrotic scar tissue, and injured tendons rarely return to native tendons, which can easily contribute to tendon reinjury. Moreover, the resulting fibrous scar is considered to be a precipitating factor for subsequent degenerative tendinopathy. Despite this, therapies are almost limited because underlying molecular mechanisms during tendon healing are still unknown. Transforming Growth Factor-β1 (TGF-β1) is known as one of most potent profibrogenic factors during tendon healing process. However, blockage TGF-β1 fails to effectively enhance tendon healing. A detailed understanding of real abilities of TGF-β1 involved in tendon healing can bring promising perspectives for therapeutic value that improve the tendon healing process. Thus, in this review, we describe recent efforts to identify and characterize the roles and mechanisms of TGF-β1 involved at each stage of the tendon healing and highlight potential roles of TGF-β1 leading to the fibrotic response to tendon injury.

From fetal tendon regeneration to adult therapeutic modalities: TGF-β3 in scarless healing

Tendon injuries are common disorders that can significantly impact people's lives. Unfortunately, the limited regenerative ability of tendons results in tissue healing in a scar-mediated manner. The current therapeutic strategies fail to fully recover the functions of the injured tendons, and as such, the conception of 'scarless healing' has gained prominent attention in the field of regenerative medicine. Interestingly, injured fetal tendons possess the capability to heal through regeneration, which builds an ideal blueprint for adult tendon regeneration. Studies have shown that fetal biochemical cues have the potential to improve adult tendon healing. Here we review the biological factors that contribute to fetal tendon regeneration and how manipulation of these biochemical cues in the adult tendon healing process could achieve regeneration.

Inflammation-related signaling pathways in tendinopathy

Tendon is a connective tissue that produces movement by transmitting the force produced by muscle contraction to the bones. Most tendinopathy is caused by prolonged overloading of the tendon, leading to degenerative disease of the tendon. When overloaded, the oxygen demand of tenocytes increases, and the tendon structure is special and lacks blood supply, which makes it easier to form an oxygen-deficient environment in tenocytes. The production of reactive oxygen species due to hypoxia causes elevation of inflammatory markers in the tendon, including PGE2, IL-1β, and TNF-α. In the process of tendon healing, inflammation is also a necessary stage. The inflammatory environment formed by cytokines and various immune cells play an important role in the clearance of necrotic material, the proliferation of tenocytes, and the production of collagen fibers. However, excessive inflammation can lead to tendon adhesions and hinder tendon healing. Some important and diverse biological functions of the body originate from intercellular signal transduction, among which cytokine mediation is an important way of signal transduction. In particular, NF-κB, NLRP3, p38/MAPK, and signal transducer and activator of transcription 3, four common signaling pathways in tendinopathy inflammatory response, play a crucial role in the regulation and transcription of inflammatory factors. Therefore, summarizing the specific mechanisms of inflammatory signaling pathways in tendinopathy is of great significance for an in-depth understanding of the inflammatory response process and exploring how to inhibit the harmful part of the inflammatory response and promote the beneficial part to improve the healing effect of the tendon.

Enthesitis in Spondyloarthritis Including Psoriatic Arthritis-To Inject or Not To Inject?: A Narrative Review

PURPOSE

Enthesitis is a key manifestation of psoriatic arthritis (PsA) and spondyloarthritis (SpA) and is considered to be the tissue where the disease initiates. Enthesitis leads to pain and substantial limitations in patients with PsA. Treatment is key in achieving remission or minimal disease activity. Whether it is safe to apply injections to entheseal tissue is unknown. This narrative review aimed to summarize the literature on the efficacy and tolerability of entheseal corticosteroid (CS) injections.

METHODS

The published literature was searched through PubMed as well as identifying relevant articles from their citations,  for articles on the anatomic location of the injection, tissue characteristics (eg, whether there is a tendon sheath), blind versus imaging-guided and entheseal versus perientheseal injections, and related studies in animals. Given that articles on SpA are limited, those on mechanical enthesopathies were also included.

FINDINGS

The literature on the efficacy and tolerability of entheseal CS injection in SpA and PsA are limited. In most articles on entheseal injection, the entheseal tissue has not actually been targeted. The decision of entheseal injection should be made on an individual basis, with consideration of the use of CS injection as the last treatment option following more conservative measures such as NSAIDs, physiotherapy, rest, and lifestyle modifications. Entheseal injection should be avoided in high-risk patients, such as those who have rupture at the enthesis. Diagnostic ultrasound is advised to ensure the presence of inflammation that can potentially benefit from corticosteroid injection, as well as the absence of rupture. In the authors' perspective, perientheseal injections should be tried before intraentheseal injections. Finally, ultrasound guidance for needle placement is strongly encouraged.

IMPLICATIONS

The literature on the efficacy and tolerability of entheseal CS injection in SpA and PsA is limited. With the lack of quality data, recommendations on entheseal corticosteroid injection remain expert opinion.

Angiogenesis and Tissue Repair Depend on Platelet Dosing and Bioformulation Strategies Following Orthobiological Platelet-Rich Plasma Procedures: A Narrative Review

Angiogenesis is the formation of new blood vessel from existing vessels and is a critical first step in tissue repair following chronic disturbances in healing and degenerative tissues. Chronic pathoanatomic tissues are characterized by a high number of inflammatory cells; an overexpression of inflammatory mediators; such as tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1); the presence of mast cells, T cells, reactive oxygen species, and matrix metalloproteinases; and a decreased angiogenic capacity. Multiple studies have demonstrated that autologous orthobiological cellular preparations (e.g., platelet-rich plasma (PRP)) improve tissue repair and regenerate tissues. There are many PRP devices on the market. Unfortunately, they differ greatly in platelet numbers, cellular composition, and bioformulation. PRP is a platelet concentrate consisting of a high concentration of platelets, with or without certain leukocytes, platelet-derived growth factors (PGFs), cytokines, molecules, and signaling cells. Several PRP products have immunomodulatory capacities that can influence resident cells in a diseased microenvironment, inducing tissue repair or regeneration. Generally, PRP is a blood-derived product, regardless of its platelet number and bioformulation, and the literature indicates both positive and negative patient treatment outcomes. Strangely, the literature does not designate specific PRP preparation qualifications that can potentially contribute to tissue repair. Moreover, the literature scarcely addresses the impact of platelets and leukocytes in PRP on (neo)angiogenesis, other than a general one-size-fits-all statement that "PRP has angiogenic capabilities". Here, we review the cellular composition of all PRP constituents, including leukocytes, and describe the importance of platelet dosing and bioformulation strategies in orthobiological applications to initiate angiogenic pathways that re-establish microvasculature networks, facilitating the supply of oxygen and nutrients to impaired tissues.

Hyaluronic acid/platelet rich plasma-infused core-shell nanofiber membrane to prevent postoperative tendon adhesion and promote tendon healing

An anti-adhesive barrier membrane incorporating hyaluronic acid (HA) can reduce fibroblasts attachment and impart lubrication effect for smooth tendon gliding during management of post-surgical tendon adhesion. On the other hand, as numerous growth factors are required during tendon recovery, growth factors released by platelets in platelet-rich plasma (PRP) can provide beneficial therapeutic effects to facilitate tendon recovery post tendon injury. Furthermore, PRP is reported to be associated with anti-inflammatory properties for suppressing postoperative adhesion. Toward this end, we fabricate core-shell nanofiber membranes (NFM) with HA/PRP-infused core and polycaprolactone shell in this study. Different NFM with 100 % (H-P), 75 % (HP31-P), 50 % (HP11-P) and 25 % (H31-P) HA in the core was fabricated through coaxial electrospinning and analyzed through microscopic, pore size, mechanical, as well as HA and growth factor release studies. In vitro study with fibroblasts indicates the NFM can act as a barrier to prevent cell penetration and reduce cell attachment/focal adhesion, in addition to promoting tenocyte migration in tendon healing. In vivo studies in a rabbit flexor tendon rupture model indicates the HP11-P NFM shows improved efficacy over H-P NFM and control in reducing tendon adhesion formation and inflammation, while promoting tendon healing, from functional assays and histological analysis.

Tendon tissue engineering: An overview of biologics to promote tendon healing and repair

Tendons are dense connective tissues with a hierarchical polarized structure that respond to and adapt to the transmission of muscle contraction forces to the skeleton, enabling motion and maintaining posture. Tendon injuries, also known as tendinopathies, are becoming more common as populations age and participation in sports/leisure activities increases. The tendon has a poor ability to self-heal and regenerate given its intrinsic, constrained vascular supply and exposure to frequent, severe loading. There is a lack of understanding of the underlying pathophysiology, and it is not surprising that disorder-targeted medicines have only been partially effective at best. Recent tissue engineering approaches have emerged as a potential tool to drive tendon regeneration and healing. In this review, we investigated the physiochemical factors involved in tendon ontogeny and discussed their potential application in vitro to reproduce functional and self-renewing tendon tissue. We sought to understand whether stem cells are capable of forming tendons, how they can be directed towards the tenogenic lineage, and how their growth is regulated and monitored during the entire differentiation path. Finally, we showed recent developments in tendon tissue engineering, specifically the use of mesenchymal stem cells (MSCs), which can differentiate into tendon cells, as well as the potential role of extracellular vesicles (EVs) in tendon regeneration and their potential for use in accelerating the healing response after injury.

Effects of splinting and three injection therapies (corticosteroid, autologous blood and prolotherapy) on pain, grip strength, and functionality in patients with lateral epicondylitis

Objectives

This study aims to compare the efficacy of the wrist splint and the injection of corticosteroid, autologous blood, and hypertonic dextrose in the treatment of lateral epicondylitis (LE).

Patients and methods

A total of 120 patients (43 males, 77 females; mean age: 45.7±7.7 years; range, 18 to 65 years) diagnosed with LE between December 2013 and June 2015 were included in the study and randomized into four groups. The first group was administered 20 mg methylprednisolone acetate + 2 mL 2% prilocaine, the second group 2 mL venous blood + 0.5 mL prilocaine, and the third group 2 mL 30% dextrose + 0.5 mL prilocaine injections. A second injection was administered to the third group one month later. The fourth group was recommended to use only a wrist splint. Pre-treatment and post-treatment evaluations of the patients were carried out at one and six months by the Visual Analog Scale (VAS) in terms of pain, by Patient-Rated Tennis Elbow Evaluation (PRTEE) questionnaire in terms of functional level, and by the Jamar dynamometer in terms of grip strength.

Results

In all groups, VAS values at one and six months after treatment were found to be lower in comparison to baseline. Except for the splint group, a significant improvement was observed in all three injection groups in terms of grip strength and PRTEE values at six months compared to the baseline values. In the comparison of the groups, no significant difference was observed in terms of improvement in VAS scores and grip strength. While corticosteroid injection was significantly effective in terms of PRTEE pain, function, and total scores only at one month, the autologous injection was effective in terms of PRTEE function and total scores at only six months after treatment. There were no significant differences for splint and prolotherapy groups in terms of PRTEE scores.

Conclusion

Corticosteroid injection, autologous blood injection, and prolotherapy are effective and safe long-term methods in LE treatment.

Platelet-rich plasma (PRP) augmentation does not result in more favourable outcomes in arthroscopic meniscal repair: a meta-analysis

Background

The efficacy and safety of platelet-rich plasma (PRP) augmentation for arthroscopic meniscal repair is controversial. This meta-analysis compared arthroscopic meniscal repair performed in isolation or augmented with PRP.

Methods

The present study was conducted according to PRISMA 2020 guidelines. Pubmed, Web of Science, Google Scholar and Embase were accessed in August 2021. All the clinical trials which compared arthroscopic meniscal repair performed in isolation or augmented with PRP were included.

Results

Eight hundred thirty-seven patients were included: 38% (318 of 837 patients) were women; the mean age of the patients was 35.6 (range, 20.8–64.3) years; the mean follow-up was 26.2 (range, 6–54) months. Similarity was found in analogue scale (VAS) (P = 0.5) and Lysholm (P = 0.9), and International Knee Documentation Committee (IKDC) scores (P = 0.9). Similarity was found in the rate of failure (P = 0.4) and rate of revision (P = 0.07).

Conclusion

The current published scientific evidence does not support PRP augmentation for arthroscopic meniscal repair.

Bioengineered endometrial hydrogels with growth factors promote tissue regeneration and restore fertility in murine models

Extracellular matrix (ECM) hydrogels obtained from decellularized tissues are promising biocompatible materials for tissue regeneration. These biomaterials may provide important options for endometrial pathologies such as Asherman's syndrome and endometrial atrophy, which lack effective therapies thus far. First, we performed a proteomic analysis of a decellularized endometrial porcine hydrogel (EndoECM) to describe the specific role of ECM proteins related to regenerative processes. Furthermore, we investigated the ability of a bioengineered system-EndoECM alone or supplemented with growth factors (GFs)-to repair the endometrium in a murine model of endometrial damage. For this model, the uterine horns of female C57BL/6 mice were first injected with 70% ethanol, then four days later, they were treated with: saline (negative control); biotin-labeled EndoECM; or biotin-labeled EndoECM plus platelet-derived GF, basic fibroblast GF, and insulin-like GF 1 (EndoECM+GF). Endometrial regeneration and fertility restoration were evaluated by assessing the number of glands, endometrial area, cell proliferation, neaoangiogenesis, reduction of collagen deposition, and fertility restoration. Interestingly, regenerative effects such as an increased number of endometrial glands, increased area, high cell proliferative index, development of new blood vessels, reduction of collagen deposition, and higher pregnancy rate occurred in mice treated with EndoECM+GF. Thus, a bioengineered system based on EndoECM hydrogel supplemented with GFs may be promising for the clinical treatment of endometrial conditions such as Asherman's syndrome and endometrial atrophy. STATEMENT OF SIGNIFICANCE: In the last years, the bioengineering field has developed new and promising approaches to regenerate tissues or replace damaged and diseased tissues. Bioengineered hydrogels offer an ideal option because these materials can be used not only as treatments but also as carriers of drugs and other therapeutics. The present work demonstrates for the first time how hydrogels derived from pig endometrium loaded with growth factors could treat uterine pathologies in a mouse model of endometrial damage. These findings provide scientific evidence about bioengineered hydrogels based on tissue-specific extracellular matrix offering new options to treat human infertility from endometrial causes such as Asherman's syndrome or endometrial atrophy.

Early-Stage Primary Anti-inflammatory Therapy Enhances the Regenerative Efficacy of Platelet-Rich Plasma in a Rabbit Achilles Tendinopathy Model

BACKGROUND

Tendinopathy is a pervasive clinical problem that afflicts both athletes and the general public. Although the inflammatory changes in tendinopathy are well characterized, how the therapeutic effects of platelet-rich plasma (PRP) on tendinopathy are being modulated by the inflammatory environment is not well defined.

PURPOSE/HYPOTHESIS

In this study, we aimed to compare the therapeutic effects of PRP alone versus a combination of PRP with a primary glucocorticoid (GC) injection at the early stage of tendinopathy. We hypothesized that PRP treatment could promote better tendon regeneration through the suppression of inflammation with GC.

STUDY DESIGN

Controlled laboratory study.

METHODS

The gene expression profile of tendon stem/progenitor cells (TSPCs) cultured with PRP was analyzed with RNA sequencing. To evaluate the cell viability, senescence, and apoptosis of TSPCs under different conditions, TSPCs were treated with 0.1 mg/mL triamcinolone acetonide (TA) and/or 10% PRP in an IL1B-induced inflammatory environment. To further verify the effects of the sequential therapy of GCs and PRP, an early tendinopathy animal model was established through a local injection of collagenase in the rabbit Achilles tendon. The tendinopathy model was then treated with isopycnic normal saline (NS group), TA (TA group), PRP (PRP group), or TA and PRP successively (TA+PRP group). At 8 weeks after treatment, the tendons were assessed with magnetic resonance imaging (MRI), histological examination, transmission electron microscopy (TEM), and mechanical testing.

RESULTS

Gene Ontology enrichment analysis indicated that PRP treatment of TPSCs induced an inflammatory response, regulated cell migration, and remodeled the extracellular matrix. Compared with the sole use of PRP, successive treatment with TA followed by PRP yielded similar results in cell viability and senescence but less cell apoptosis in vitro. In vivo experiments demonstrated that the TA+PRP group achieved significantly better tendon regeneration, as confirmed by MRI, histological examination, TEM, and mechanical testing.

CONCLUSION

This study showed that the primary use of GCs did not exert any obvious deleterious side effects on the treated tendon but instead enhanced the regenerative effects of PRP in early inflammatory tendinopathy.

CLINICAL RELEVANCE

The sequential therapy of GCs followed by PRP provides a promising treatment strategy for tendinopathy in clinical practice. PRP combined with the primary use of GCs appears to promote tendon regeneration in early inflammatory tendinopathy.

Platelet HMGB1 in Platelet-Rich Plasma (PRP) promotes tendon wound healing

Platelet-rich plasma (PRP) is a widely used autologous treatment for tendon injuries in clinics. Platelets (PLTs) are a major source of high mobility group box1 (HMGB1) that is gaining attention as a chemoattractant that can recruit stem cells to the wound area to enhance healing of injured tissues; however, the contribution of PLT HMGB1 in wounded tendon healing remains unexplored. This study investigated the effect of PLT HMGB1 within PRP on tendon healing using PLT HMGB1 knockout (KO) and GFP mice. A window defect was created in the patellar tendons of both groups of mice, and wounds were treated with either saline, PRP isolated from PLT HMGB1-KO mice, or PRP isolated from GFP mice. Seven days post-treatment, animals were sacrificed and analyzed by gross inspection, histology, and immunostaining for characteristic signs of tendon healing and repair. Our results showed that in comparison to mice treated with PRP from PLT HMGB1-KO mice, wounds treated with PRP from GFP mice healed faster and exhibited a better organization in tendon structure. Mice treated with PRP from PLT HMGB1-KO mice produced tendon tissue with large premature wound areas and low cell densities. However, wounds of PLT HMGB1-KO mice showed better healing with PRP from HMGB1-KO mice compared to saline treatment. Moreover, wounds treated with PRP from GFP mice had increased extracellular HMGB1, decreased CD68, increased stem cell markers CD146 and CD73, and increased collagen III protein expression levels compared to those treated with PRP from PLT HMGB1-KO mice. Thus, PLT HMGB1 within PRP plays an important role in tendon wound healing by decreasing inflammation, increasing local HMGB1 levels, and recruiting stem cells to the wound area in the tendon. Our findings also suggest that the efficacy of PRP treatment for tendon injuries in clinics may depend on PLT HMGB1 within PRP preparations.

[Platelet-rich plasma alleviates myocardial ischemia-reperfusion injury in rats]

OBJECTIVE

To investigate the protective effect of platelet-rich plasma (PRP) against acute myocardial ischemiareperfusion (IR) injury and the possible mechanism.

OBJECTIVE

Aortic blood samples were collected from 10 SD rats to prepare PRP, in which the concentrations of platelet-derived growth factor-BB (PDGF-BB) and transforming growth factor-β1 (TGF-β1) were measured. Cell models of IR injury were established in primary cultures of neonatal SD rat cardiomyocytes by exposing the cells to 3 h of hypoxia. The cells were then reoxygenated and co-cultured with 1%, 5%, 10%, and 20% volume of PRP for 12 h, and the changes in cell viability was assessed. Immunofluorescence staining of the cardiomyocytes was performed, and the cellular expression of AMPK and its phosphorylation level were detected. The effects of PRP on the proliferation and migration of rat aortic endothelial cells (RAOECs) were examined. In a SD rat model of myocardial IR injury, 100 μL of PRP (n= 20) or normal saline (n=20) was injected at 4 sites around the ligation site immediately after cardiac reperfusion. One day after the injection, 6 rats were selected from each group for TTC staining of the myocardial tissues and measurement of troponin Ⅰ content. One week later, the cardiac function of the remaining rats was assessed by echocardiography, and HE staining of the myocardial tissues was performed. The effect of PRP treatment for 24 h on polarization of M1 and M2 macrophages was also examined by flow cytometry in RAW264.7 cells after hypoxic exposure for 3 h.

OBJECTIVE

The concentrations of PDGF-BB and TGF-β1 were significantly higher in PRP than in whole blood. Addition of 1% volume of PRP significantly reduced death of the cardiomyocytes following reoxygenation, and this effect was closely related with the activation of AMPK. Treatment with PRP obviously promoted the proliferation and migration of RAOECs. In rat models of acute myocardial IR injury, injections of PRP significantly reduced the infarct size and troponin Ⅰ concentration as compared with saline injection (P < 0.001). One week after PRP injection, the rats showed significantly improved cardiac function with a lowered level of inflammatory response in comparison with the rats with saline injection. In RAW264.7 cells with hypoxic exposure, treatment with PRP obviously decreased the number of M1 macrophages and increase the number of M2 macrophages.

OBJECTIVE

PRP can improve acute myocardial IR injury in rats by phosphorylating AMPK and regulating macrophage polarization, which produces a protective immunomodulatory effect on the ischemic myocardial tissues.

The effect of the platelet-rich plasma and ozone therapy on tendon-to-bone healing in the rabbit rotator cuff repair model

Background

The aim of this study is to histologically and biomechanically investigate the effects of local PRP and ozone therapy (O₂O₃) on tendon-to-bone healing in a rabbit model of the supraspinatus tendon tear.

Methods

Four groups were formed to have seven rabbits in each group: repair, R; repair + PRP, RP; repair + ozone, RO; and repair + PRP + ozone, RPO. The supraspinatus tendon was detached by sharp dissection from the footprint and an acute tear pattern was created. Thereafter, tendon repair was performed with the transosseous technique. In the RP group, PRP, and in the RPO group, PRP + O2O3 mixture was injected to the tendon repair site. In the RO group, O₂O₃ gas mixture was injected into subacromial space three times a week for a total of 4 weeks. The study was ended at postoperative 6th week.

Results

When compared with the R group, a statistically significant increase was observed in the biomechanical strength of the RP and RPO groups. The highest increase in biomechanical strength was detected in the RPO group. The histology of the RO and RPO groups showed better collagen fiber continuity and orientation than the R and RP groups.

Conclusions

The results obtained from this study show that the ozonized PRP can be used as biological support to increase tendon-to-bone healing. However, these results need to be supported by clinical studies.

Systemic effects of platelet-rich plasma local injection on serum and urinary anabolic metabolites: A prospective randomized study

Platelet-rich plasma (PRP) is widely utilized in the treatment of sports injuries. However, potential systemic effects after localized PRP injection are unclear at present. In this prospective randomized study, 24 Taiwanese male athletes with tendinopathy were randomized into a PRP group (n = 13) or a saline group (n = 11). The concentrations of serum and urine biomarkers were quantified by enzyme-linked immunosorbent assay assessment as well as gas chromatographic and mass spectrometric analysis, respectively. The results showed no significant differences in serum levels of growth hormone, insulin-like growth factor-1, insulin-like growth factor-binding protein 3, vascular endothelial growth factor, platelet-derived growth factor-BB, or serum substance P(SP) between the two groups before intervention, nor at 1, 2, or 7 days after intervention. However, a significant decrease in the serum SP level 1 and 7 days after PRP injection was observed. Regarding urinary concentrations of metabolites of anabolic androgenic steroids (AAS), no between-group differences before intervention, nor at 1, 2, or 7 days after intervention, were observed. Our study failed to observe significant surge of serum anabolic molecules and urinary excretion of anabolic AAS metabolites after PRP injection.

Effect of Platelet-Rich Plasma on Nonsurgically Treated Acute Achilles Tendon Ruptures: A Randomized, Double-Blinded Prospective Study

BACKGROUND

An acute Achilles tendon rupture (ATR) is a long-lasting and devastating injury. Possible biological augmentation to promote and strengthen tendon healing after an ATR would be desirable.

PURPOSE

To determine whether the application of a platelet-rich plasma (PRP) injection in nonsurgically treated ATRs may promote healing and thereby improve functional outcomes.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

A total of 40 men (aged 18-60 years) with an ATR incurred within 72 hours were included, and 38 were followed for 12 months. All patients were treated with an orthosis with 3 wedges for 8 weeks; full weightbearing from day 1 was allowed, combined with either 4 PRP or 4 placebo injections (a few drops of saline, <0.5 mL, under the skin) 14 days apart. All patients received the same instructions on an exercise program starting from week 9. Outcomes included the self-reported Achilles tendon Total Rupture Score (ATRS) as well as heel-rise work, heel-rise height, tendon elongation, calf circumference, and ankle dorsiflexion range of motion.

RESULTS

The mean ATRS score improved in both groups at all time points (P < .001), but there was no difference between the groups at any time points (12 months: 90.1 points in PRP group and 88.8 points in placebo group). No differences in all functional outcomes at any time points were seen between the groups. At 12 months, the injured leg did not reach normal functional values compared with the uninjured leg.

CONCLUSION

The application of PRP in nonsurgically treated ATRs did not appear to show any superior clinical and functional improvement.

REGISTRATION

NCT02417922 (ClinicalTrials.gov identifier).

Comparison of Leukocyte-Rich Platelet-Rich Plasma and Leukocyte-Poor Platelet-Rich Plasma on Achilles Tendinopathy at an Early Stage in a Rabbit Model

BACKGROUND

Tendinopathy is still a great challenge in clinical practice, and the role of platelet-rich plasma (PRP) is controversial. The influence of leukocytes on tendinopathy at an early stage has not been defined so far.

PURPOSE

To compare the effects of leukocyte-rich PRP (Lr-PRP) and leukocyte-poor PRP (Lp-PRP) on Achilles tendinopathy when applied at an early stage.

STUDY DESIGN

Controlled laboratory study.

METHODS

A rabbit Achilles tendinopathy model was induced by a collagenase injection. A week later, treatments were applied randomly on local Achilles tendon lesions: (1) 200 μL of Lr-PRP (16 legs), (2) 200 μL of Lp-PRP (16 legs), and (3) 200 μL of saline (16 legs). At 3 and 6 weeks after the collagenase injection, outcomes were evaluated by histology, magnetic resonance imaging (MRI), real-time polymerase chain reaction analysis, immunohistochemistry, and transmission electron microscopy (TEM).

RESULTS

The Lr-PRP group had a lower T2 signal intensity (P = .0377) and smaller diameter (P = .0193) and cross-sectional area (P = .0194) than the Lp-PRP group on MRI. Histologically, the Lr-PRP group had better scores than the Lp-PRP group (P = .0284 and P = .0188, respectively). Compared with the Lp-PRP group, higher gene expression and more protein synthesis of collagen I (P = .0160 and P = .0309, respectively) and CD163 (P < .0001 and P = .0411, respectively) were found in the Lr-PRP group. Considering TEM and biomechanical testing, the Lr-PRP group demonstrated more mature collagen fibers (P < .0001), a larger fiber diameter (P = .0005), a higher failure load (P = .00417), and higher tensile stress (P < .0001) than the Lp-PRP group.

CONCLUSION

Lr-PRP had more beneficial effects than Lp-PRP when delivered at an early stage during tendon repair.

CLINICAL RELEVANCE

Here, we showed that tendinopathy influenced the curative effects of PRP in vivo. An early-stage application of Lr-PRP had more benefits for the repair of tendinopathy than Lp-PRP in a rabbit model, which will supplement guidelines of PRP treatment on tendinopathy clinically.

The Effect of Delayed Injection of Leukocyte-Rich Platelet-Rich Plasma Following Rotator Cuff Repair on Patient Function: A Randomized Double-Blind Controlled Trial

PURPOSE

To investigate the effect of delayed application of leukocyte-rich platelet-rich plasma (PRP) on rotator cuff repair results as assessed by outcome scores and imaging at one year.

METHODS

Patients with a symptomatic rotator cuff tear awaiting arthroscopic repair were approached to take part in the study. Final eligibility for the study was confirmed at the time of surgery. A total of 97 patients were randomized to an ultrasound guided injection of leukocyte-rich PRP or normal saline between 10 and 14 days postsurgery. A total of 87 patients completed clinical evaluation and underwent magnetic resonance imaging imaging at 1 year. Outcome scores included the American Shoulder and Elbow Score, Constant score, Western Ontario Rotator Cuff Index, and the Disabilities of the Arm, Shoulder and Hand Score. Structural integrity of the repair was assessed according to the Sugaya grading. Muscle fatty infiltration was assessed on magnetic resonance imaging using the Goutallier classification.

RESULTS

At 1 year postsurgery, there was no significant difference between the treatment groups on any of the patient-reported outcome measures or Constant score. On postoperative imaging analysis, there was no difference in the retear rates (Sugaya 4 and 5) between the groups (21% in control group vs 15.3% in PRP group). Fatty infiltration on postoperative imaging was found to be significantly higher in the normal saline group compared with the PRP group (Kendall's tau-b P = .032).

CONCLUSIONS

The delayed application of PRP postrotator cuff repair did not improve function as measured by patient-reported outcome measures and Constant score at 1 year postoperatively.

LEVEL OF EVIDENCE

Level II, prospective randomized therapeutic trial.

Efficacy of platelet-rich plasma as an adjuvant to surgical carpal ligament release: a prospective, randomized controlled clinical trial

The purpose of this study is to evaluate the efficiency of local platelet-rich plasma (PRP) injection as an adjuvant treatment after carpal ligament release. We conducted a prospective randomized, triple-blinded, controlled trial. Fifty participants with mild to extreme carpal tunnel syndrome (CTS) were randomly assigned either to the PRP (n = 25) or the platelet-poor plasma (PPP, n = 25) group. After performing open surgical release of the carpal ligament, the inside of the carpal tunnel was irrigated with 3 mL of PRP or PPP according to each participant’s group allocation. The primary outcome was hand grip strength (HGS). Secondary outcomes were the time taken off work after surgery (in days) and scores on the Wong–Baker Faces Scale, Boston Carpal Tunnel Questionnaire, and Southampton Wound Assessment Scale. We evaluated patients before treatment and at 6-weeks. As expected, the pain levels, symptom severity, and functional status improved in all the patients after surgery. However, intragroup analysis revealed that only the participants in the PRP group had regained their pre-operative HGS levels at 6-weeks follow-up. These findings indicate that PRP is an effective adjuvant treatment in patients with mild to severe CTS who require surgery.

A Practical Guide for the Current Use of Biologic Therapies in Sports Medicine

Over the past decade, there has been an increased interest in the use of biologic therapies in sports medicine. Although these technologies are in relatively early stages of development, there have been substantial increases in marketing, patient demand, and clinical utilization of biologics, including platelet-rich plasma, bone marrow aspirate concentrate, and other cell-derived therapies. Direct-to-consumer marketing of biologics has also proliferated but is largely unregulated, and clinicians must accurately convey the safety and efficacy profiles of these therapies to patients. Because most insurance companies consider biologic treatments to be experimental or investigational for orthopaedic applications given the lack of high-quality evidence to support their efficacy, patients receiving these treatments often make substantial out-of-pocket payments. With a range of treatment costs among centers offering biologics, there is a need for appropriate and sustainable pricing and reimbursement models. Clinicians utilizing biologics must also have a thorough understanding of the recently clarified Food and Drug Administration guidelines that regulate the clinical use of cell and tissue products. There is a lack of consensus on the optimal preparation, source, delivery method, and dosing of biologic therapies, which has been exacerbated by a lack of sufficient experimental detail in most published studies. Future research must better identify the biologic target of treatment, adhere to better standards of reporting, and better integrate researchers, industry, and regulatory bodies to optimize applications.

Platelet-Rich Plasma Released From Polyethylene Glycol Hydrogels Exerts Beneficial Effects on Human Chondrocytes

Osteoarthritis (OA) is a debilitating joint disease resulting from chronic joint inflammation and erosion of articular cartilage. A promising biological treatment for OA is intra-articular administration of platelet-rich plasma (PRP). However, immediate bolus release of growth factors limits beneficial therapeutic effects of PRP, thus necessitating the demand for sustained release platforms. In this study, we evaluated the therapeutic value of PRP released from a polyethylene glycol (PEG) hydrogel on articular chondrocytes/cartilage explants derived from OA patients. Lyophilized PRP (PRGF) was encapsulated in PEG hydrogels at 10% w/v and hydrogel swelling, storage modulus and degradation and PRGF release kinetics were determined. PRGF releasate from the hydrogels was collected on day 1, 4, and 11. Encapsulation of PRGF at 10% w/v in PEG hydrogels had minimal effect on hydrogel properties. PRGF was released with an initial burst followed by sustained release until complete hydrogel degradation. Effect of PRGF releasates and bolus PRGF (1% w/v PRGF) on patient-derived cartilage explants or chondrocytes was assessed by chondrocyte proliferation (pico-green assay), gene expression for COL1A1, COL2A1, MMP13, COX2, and NFKB1 (real-time polymerase chain reaction), and measurement of nitric oxide concentration (Griess' assay). Compared to bolus PRGF, PRGF releasates enhanced chondrocyte proliferation, suppressed the expression of genes like MMP13, NFKB1, COL1A1, and COL2A1 and reduced levels of nitric oxide. Taken together, these results indicate that release of PRGF from PEG hydrogels may improve the therapeutic efficacy of PRP and merits further investigation in an animal model of OA. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2401-2410, 2019.

Selectively activated PRP exerts differential effects on tendon stem/progenitor cells and tendon healing

To understand the variable efficacy with platelet rich plasma (PRP) treatments for tendon injury, we determined the differential effects of proteinase-activated receptor (PAR)1- or PAR4-activated PRP (PAR1-PRP, PAR4-PRP) from humans on human patellar tendon stem/progenitor cells (TSCs) and tendon healing. We show that PAR1-PRP released VEGF, whereas PAR4-PRP released endostatin. Treatment of TSCs with PAR1-PRP increased collagen I expression and matrix metalloproteinase-1 (MMP-1), but cells treated with PAR4-PRP increased less collagen I and higher MMP-2 expression. The wound area treated with PAR4-PRP formed tendon-like tissues with well-organized collagen fibers and fewer blood vessels, while PAR1-PRP treatment resulted in the formation of blood vessels and unhealed tissues. These findings indicate that differential activation of PRP leads to different effects on TSCs and tendon healing. We suggest that based on acute or chronic type of tendon injury, selective activation of PRP should be applied in clinics in order to treat injured tendons successfully.

The efficacy and safety of platelet-rich fibrin for rotator cuff tears: a meta-analysis

Background

The aim of this meta-analysis was to evaluate the efficacy and safety of platelet-rich fibrin (PRF) in improving clinical outcomes in rotator cuff tears.

Methods

We searched the following databases: Pubmed, Embase, and Cochrane library databases from inception to April 2018. Studies that compared platelet-rich fibrin versus placebo for rotator cuff tears were included in this meta-analysis. Risk ratio (RR) with 95% confidence interval (CI) was pooled for discontinuous outcome, and weighted mean difference (WMD) with 95% CI was pooled for continuous outcome. Stata 12.0 was used for meta-analysis.

Results

A total of eight studies with 219 patients were finally included in this meta-analysis. Compared with the control group, PRF has a negative role in reducing the re-tear rate (RR = 1.30, 95% CI = 0.97 to 1.75; P = 0.082). Subgroup analysis of re-tear rate was consistent in all subgroup analyses (single row or double row, volume, and risk of bias). There was no significant difference between the American Shoulder and Elbow Surgeons scale, University of California at Los Angeles scale, Constant score, and side effect (P > 0.05).

Conclusion

In conclusion, our meta-analysis suggests that the PRF does not have better effect on improving the overall clinical outcomes and re-tear rate in the arthroscopic repair of rotator cuff tears.

Is Platelet-rich Plasma Injection Effective for Chronic Achilles Tendinopathy? A Meta-analysis

BACKGROUND

Chronic Achilles tendinopathy is common in the general population, and platelet-rich plasma (PRP) is seeing increased use to treat this problem. However, studies disagree as to whether PRP confers a beneficial effect for chronic Achilles tendinopathy, and no one to our knowledge has pooled the available randomized trials in a formal meta-analysis to try to reconcile those differences.

QUESTIONS/PURPOSES

In the setting of a systematic review and meta-analysis of randomized controlled trials (RCTs), we asked: Does PRP plus eccentric strength training result in (1) greater improvements in Victorian Institute of Sports Assessment-Achilles (VISA-A) scores; (2) differences in tendon thickness; or (3) differences in color Doppler activity compared with placebo (saline) injections plus eccentric strength training in patients with chronic Achilles tendinopathy?

METHODS

A search of peer-reviewed articles was conducted to identify all RCTs using PRP injection with eccentric training for chronic Achilles tendinopathy in the electronic databases of PubMed, Web of Science (SCI-E/SSCI/A&HCI), and EMBASE from January 1981 to August 2017. Results were limited to human RCTs and published in all languages. Two reviewers assessed study quality using the Cochrane Collaboration risk-of-bias tool. All the included studies had low risk of bias. The primary endpoint was improvement in the VISA-A score, which ranges from 0 to 100 points, with higher scores representing increased activity and less pain; we considered the minimum clinically important difference on the VISA-A to be 12 points. Secondary outcomes were tendon thickness change (with a thicker tendon representing more severe disease), color Doppler activity (with more activity representing a poorer result), and other functional measures (such as pain and return to sports activity). Four RCTs involving 170 participants were eligible and included 85 participants treated with PRP injection and eccentric training and 85 treated with saline injection and eccentric training. The patients in both PRP and placebo (saline) groups seemed comparable at baseline. We assessed for publication bias using a funnel plot and saw no evidence of publication bias. Based on previous studies, we had 80% power to detect a 12-point difference on the VISA-A score with the available sample size in each group.

RESULTS

With the numbers available, there was no difference between the PRP and saline groups regarding the primary outcome (VISA-A score: mean difference [MD], 5.3; 95% confidence interval [CI], -0.7 to 11.3; p = 0.085). Likewise, we found no difference between the PRP and saline groups in terms of our secondary outcomes of tendon thickness change (MD, 0.2 mm; 95% CI, 0.6-1.0 mm; p = 0.663) and color Doppler activity (MD, 0.1; 95% CI, -0.7 to 0.4; p = 0.695).

CONCLUSIONS

PRP injection with eccentric training did not improve VISA-A scores, reduce tendon thickness, or reduce color Doppler activity in patients with chronic Achilles tendinopathy compared with saline injection. Larger randomized trials are needed to confirm these results, but until or unless a clear benefit has been demonstrated in favor of the new treatment, we cannot recommend it for general use.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Italian consensus conference on guidelines for conservative treatment on lower limb muscle injuries in athlete

Provide the state of the art concerning (1) biology and aetiology, (2) classification, (3) clinical assessment and (4) conservative treatment of lower limb muscle injuries (MI) in athletes. Seventy international experts with different medical backgrounds participated in the consensus conference. They discussed and approved a consensus composed of four sections which are presented in these documents. This paper represents a synthesis of the consensus conference, the following four sections are discussed: (i) The biology and aetiology of MIs. A definition of MI was formulated and some key points concerning physiology and pathogenesis of MIs were discussed. (ii) The MI classification. A classification of MIs was proposed. (iii) The MI clinical assessment, in which were discussed anamnesis, inspection and clinical examination and are provided the relative guidelines. (iv) The MI conservative treatment, in which are provided the guidelines for conservative treatment based on the severity of the lesion. Furthermore, instrumental therapy and pharmacological treatment were discussed. Knowledge of the aetiology and biology of MIs is an essential prerequisite in order to plan and conduct a rehabilitation plan. Another important aspect is the use of a rational MI classification on prognostic values. We propose a classification based on radiological investigations performed by ultrasonography and MRI strongly linked to prognostic factors. Furthermore, the consensus conference results will able to provide fundamental guidelines for diagnostic and rehabilitation practice, also considering instrumental therapy and pharmacological treatment of MI. Expert opinion, level IV.

Biomechanical study of the effect of platelet rich plasma on the treatment of medial collateral ligament lesion in rabbits

PURPOSE

To evaluate the use of platelet-rich plasma in the early stages of healing of traumatic injury of the medial collateral ligament in the knee of rabbits.

METHODS

Thirty rabbits were subjected to surgical lesion of the medial collateral ligament. Of these, 16 were treated with platelet-rich plasma and 14 with saline (control). After 3 and 6 weeks of treatment, 50% of the animals from each group were sacrificed, and biomechanical tests were performed on the injured ligament to compare the tensile strength between the two groups.

RESULTS

Platelet-rich plasma significantly increased the tensile strength of the ligament in the groups treated after3 and 6 weeks. In the group treated with platelet-rich plasma vs. saline, the tensile strength values were 3192.5 ± 189.7 g/f vs. 2851.1 ± 193.1 g/f at3 weeks (p = 0.005) and 5915.6 ± 832.0 g/f vs. 4187.6 ± 512.9 g/f at 6 weeks (p = 0.0001).

CONCLUSION

The use of platelet-rich plasma at the injury site accelerated ligament healing in an animal model, demonstrated by an increase in the tensile strength of the medial collateral ligament.

Exploring Stem Cells and Inflammation in Tendon Repair and Regeneration

Tendon injuries are frequent and are responsible for substantial morbidity both in sports and in the workplace. Despite the endogenous mechanisms of tendon repair and regeneration, tendon healing upon injury is slow and often insufficient to restore complete biomechanics functionality.Inflammation has a pivotal role in tendon healing and failed healing responses contribute to the progression of tendinopathies. However, the molecular and cellular mechanisms involved are poorly understood requiring further insights.During inflammation, bioactive molecules such as cytokines secreted locally at the injury site, influence resident stem cells that contribute as modulatory agents over the niche towards homeostasis, holding great promise as therapeutic agents for tendon pathological conditions associated to unresolved inflammation and failed healing.This review overviews the role of cytokines and resident cells, focusing on the participation of tendon stem cell population in inflammation and tendon healing upon injury and their potential action in resolution of pathological conditions.

Intratendon Delivery of Leukocyte-Poor Platelet-Rich Plasma Improves Healing Compared With Leukocyte-Rich Platelet-Rich Plasma in a Rabbit Achilles Tendinopathy Model

BACKGROUND

Chronic tendinopathy is a commonly occurring clinical problem that affects both athletes and inactive middle-aged patients. Although some studies have shown that different platelet-rich plasma (PRP) preparations could exert various therapeutic effects in vitro, the role of leukocytes in PRP has not yet been defined under tendinopathy conditions in vivo.

PURPOSE

This study compared the effects of the intratendon delivery of leukocyte-poor PRP (Lp-PRP) versus leukocyte-rich PRP (Lr-PRP) in a rabbit chronic tendinopathy model in vivo.

STUDY DESIGN

Controlled laboratory study.

METHODS

Four weeks after a local injection of collagenase in the Achilles tendon, the following treatments were randomly administered on the lesions: injections of (1) 200 μL of Lp-PRP (n = 8), (2) 200 μL of Lr-PRP (n = 8), or (3) 200 μL of saline (n = 8). Healing outcomes were assessed at 4 weeks after therapy with magnetic resonance imaging (MRI), cytokine quantification, real-time polymerase chain reaction analysis of gene expression, histology, and transmission electron microscopy (TEM).

RESULTS

MRI revealed that the Lr-PRP and saline groups displayed higher signal intensities compared with the Lp-PRP group with T2 mapping. Histologically, the Lp-PRP group displayed significantly better general scores compared with the Lr-PRP ( P = .001) and saline ( P < .001) groups. Additionally, TEM showed that the Lp-PRP group had larger collagen fibril diameters than the Lr-PRP group ( P < .001). Enzyme-linked immunosorbent assay showed a significantly lower level of catabolic cytokine IL-6 in the Lp-PRP group compared with the Lr-PRP ( P = .001) and saline ( P = .021) groups. The Lp-PRP group displayed significantly increased expression of collagen I compared with the saline group ( P = .004) but not the Lr-PRP group. Both the Lp-PRP and Lr-PRP groups exhibited significantly lower matrix metalloproteinase (MMP)-1 and MMP-3 expression levels compared with the saline group. However, only the Lp-PRP group displayed significantly higher expression of TIMP-1 than the saline group ( P = .024).

CONCLUSION

Compared with Lr-PRP, Lp-PRP improves tendon healing and is a preferable option for the clinical treatment of tendinopathy.

CLINICAL RELEVANCE

PRP is widely used in the clinical management of chronic tendinopathy. However, the clinical results are ambiguous. It is imperative to understand the influence of leukocytes on PRP-mediated tissue healing in vivo, which could facilitate the better clinical management of chronic tendinopathy. Further studies are needed to translate our findings to the clinical setting.

Effect of High-Volume Injection, Platelet-Rich Plasma, and Sham Treatment in Chronic Midportion Achilles Tendinopathy: A Randomized Double-Blinded Prospective Study

BACKGROUND

Injection therapies are often considered alongside exercise for chronic midportion Achilles tendinopathy (AT), although evidence of their efficacy is sparse.

PURPOSE

To determine whether eccentric training in combination with high-volume injection (HVI) or platelet-rich plasma (PRP) injections improves outcomes in AT.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 60 men (age, 18-59 years) with chronic (>3 months) AT were included and followed for 6 months (n = 57). All participants performed eccentric training combined with either (1) one HVI (steroid, saline, and local anesthetic), (2) four PRP injections each 14 days apart, or (3) placebo (a few drops of saline under the skin). Randomization was stratified for age, function, and symptom severity (Victorian Institute of Sports Assessment-Achilles [VISA-A]). Outcomes included function and symptoms (VISA-A), self-reported tendon pain during activity (visual analog pain scale [VAS]), tendon thickness and intratendinous vascularity (ultrasonographic imaging and Doppler signal), and muscle function (heel-rise test). Outcomes were assessed at baseline and at 6, 12, and 24 weeks of follow-up.

RESULTS

VISA-A scores improved in all groups at all time points ( P < .05), with greater improvement in the HVI group (mean ± SEM, 6 weeks = 27 ± 3 points; 12 weeks = 29 ± 4 points) versus PRP (6 weeks = 14 ± 4; 12 weeks = 15 ± 3) and placebo (6 weeks = 10 ± 3; 12 weeks = 11 ± 3) at 6 and 12 weeks ( P < .01) and in the HVI (22 ± 5) and PRP (20 ± 5) groups versus placebo (9 ± 3) at 24 weeks ( P < .01). VAS scores improved in all groups at all time points ( P < .05), with greater decrease in HVI (6 weeks = 49 ± 4 mm; 12 weeks = 45 ± 6 mm; 24 weeks = 34 ± 6 mm) and PRP (6 weeks = 37 ± 7 mm; 12 weeks = 41 ± 7 mm; 24 weeks = 37 ± 6 mm) versus placebo (6 weeks = 23 ± 6 mm; 12 weeks = 30 ± 5 mm; 24 weeks = 18 ± 6 mm) at all time points ( P < .05) and in HVI versus PRP at 6 weeks ( P < .05). Tendon thickness showed a significant decrease only in HVI and PRP groups during the intervention, and this was greater in the HVI versus PRP and placebo groups at 6 and 12 weeks ( P < .05) and in the HVI and PRP groups versus the placebo group at 24 weeks ( P < .05). Muscle function improved in the entire cohort with no difference between the groups.

CONCLUSION

Treatment with HVI or PRP in combination with eccentric training in chronic AT seems more effective in reducing pain, improving activity level, and reducing tendon thickness and intratendinous vascularity than eccentric training alone. HVI may be more effective in improving outcomes of chronic AT than PRP in the short term. Registration: NCT02417987 ( ClinicalTrials.gov identifier).

Clinical benefits and drawbacks of local corticosteroids injections in tendinopathies

INTRODUCTION

local glucocorticoids injections are widely administered for the treatment of tendinopathies. positive results have been observed in some tendinopathies but not in others. moreover, worsening of symptoms, and even spontaneous tendon ruptures has been reported. the characteristics of the tendinopathies, the clinical peculiarities of the patient, and the technique used to administer glucocorticoids, can influence the therapeutic response. Areas covered: After reviewing the pertinent literature on the clinical results, basic information, both on the pathogenesis of tendinopathies and the effects of glucocorticoids on tendons, is reported. The pharmacological properties of glucocorticoids are useful to counteract some pathogenetic mechanisms of tendinopathies. However, several experimental studies suggest that the direct action of glucocorticoids on tendons is detrimental. Loss of collagen organization, impaired viability of fibroblasts, depletion of stem cells pool, and reduced mechanical properties have been observed. Expert opinion: Drawbacks of local glucocorticoids injections could be predicted on an individual basis, after a careful appraisal of patient characteristics and concomitant medications, along with the specific stage of tendon disease.

Effects of plasma rich in growth factors (PRGF) on biomechanical properties of Achilles tendon repair

PURPOSE

To assess the biomechanical effects of intra-tendinous injections of PRGF on the healing Achilles tendon after repair in a sheep model.

METHODS

Thirty sheep were randomly assigned into one of the six groups depending on the type of treatment received (PRGF or placebo) and survival time (2, 4 and 8 weeks). The Achilles tendon injury was repaired by suturing the tendinous edges employing a three-loop pulley pattern. A trans-articular external fixation system was then used for immobilization. The PRGF or placebo was administered on a weekly basis completing a maximum of three infiltrations. The force, section and tension values were compared between the operated and healthy Achilles tendons across all groups.

RESULTS

The PRGF-treated tendons had higher force at 8 weeks compared with the placebo group (p = 0.007). Between 2 and 4 weeks, a significant increase in force in both the PRGF-treated tendon (p = 0.0027) and placebo group (p = 0.0095) occurred. No significant differences were found for section ratio between PRGF-treated tendons and the placebo group for any of the time periods evaluated. At 2 weeks, PRGF-treated tendons had higher tension ratio compared with placebo group tendons (p = 0.0143). Both PRGF and placebo treatments significantly improved the force (p < 0.001 and p = 0.0095, respectively) and tension (p = 0.009 and p = 0.0039, respectively) ratios at 8 weeks compared with 2 weeks.

CONCLUSION

The application of PRGF increases Achilles tendon repair strength at 8 weeks compared with the use of placebo. The use of PRGF does not modify section and tension ratios compared with placebo at 8 weeks. The tension ratio progressively increases between 2 and 8 weeks compared with the placebo.

Intra-articular therapies for osteoarthritis

INTRODUCTION

Conventional medical therapies for osteoarthritis are mainly palliative in nature, aiming to control pain and symptoms. Traditional intra-articular therapies are not recommended in guidelines as first line therapy, but are potential alternatives, when conventional therapies have failed.

AREAS COVERED

Current and future intra-articular drug therapies for osteoarthritis are highlighted, including corticosteroids, hyaluronate, and more controversial treatments marketed commercially, namely platelet rich plasma and mesenchymal cell therapy. Intraarticular disease modifying osteoarthritis drugs are the future of osteoarthritis treatments, aiming at structural modification and altering the disease progression. Interleukin-1β inhibitor, bone morphogenic protein-7, fibroblast growth factor 18, bradykinin B2 receptor antagonist, human serum albumin, and gene therapy are discussed in this review. The evolution of drug development in osteoarthritis is limited by the ability to demonstrate effect. High quality trials are required to justify the use of existing intra-articular therapies and to advocate for newer, promising therapies.

EXPERT OPINION

Challenges in osteoarthritis therapy research are fundamentally related to the complexity of the pathological mechanisms of osteoarthritis. Novel drugs offer hope in a disease with limited medical therapy options. Whether these future intra-articular therapies will provide clinically meaningful benefits, remains unknown.

Is there a treatment protocol in which platelet-rich plasma is effective?

AIM

We aimed to reveal whether there are prospective suggestions for effective and standard platelet-rich plasma applications.

METHODS

We searched for clinical trials and traced all the references of incorporated documents.

RESULTS

In literature, there was no study indicating which disease is treated by which mechanism of action, how much dose and content are prepared and applied, when the treatment is applied and how many cures are applied.

CONCLUSION

Guides introducing which concentrations of PRP are used for which diseases are to be prepared immediately by a committee which is comprised of primarily orthopedists, clinical pharmacologists and toxicologists.

AAOS Research Symposium Updates and Consensus: Biologic Treatment of Orthopaedic Injuries

Strategies that seek to enhance musculoskeletal tissue regeneration and repair by modulating the biologic microenvironment at the site of injury have considerable therapeutic potential. Current and emerging biologic approaches include the use of growth factors, platelet-rich plasma, stem cell therapy, and scaffolds. The American Academy of Orthopaedic Surgeons hosted a research symposium in November 2015 to review the current state-of-the-art biologic treatments of articular cartilage, muscle, tendon, and bone injuries and identify knowledge gaps related to these emerging treatments. This review outlines the findings of the symposium and summarizes the consensus reached on how best to advance research on biologic treatment of orthopaedic injuries.

Biologic Treatments for Sports Injuries II Think Tank-Current Concepts, Future Research, and Barriers to Advancement, Part 2: Rotator Cuff

Rotator cuff tears are common and result in considerable morbidity. Tears within the tendon substance or at its insertion into the humeral head represent a considerable clinical challenge because of the hostile local environment that precludes healing. Tears often progress without intervention, and current surgical treatments are inadequate. Although surgical implants, instrumentation, and techniques have improved, healing rates have not improved, and a high failure rate remains for large and massive rotator cuff tears. The use of biologic adjuvants that contribute to a regenerative microenvironment have great potential for improving healing rates and function after surgery. This article presents a review of current and emerging biologic approaches to augment rotator cuff tendon and muscle regeneration focusing on the scientific rationale, preclinical, and clinical evidence for efficacy, areas for future research, and current barriers to advancement and implementation.

Three-Dimensional Platelet-Rich Plasma Hydrogel Model to Study Early Tendon Healing

Since the experimental conditions of cell cultures may bias results, it is critical to use suitable models. This is also true in the context of tendon cell biology and the study of platelet-rich plasma (PRP) therapies and PRP-augmented cell-based therapies. We compared the culture of human tendon cells in 2 dimensions (2D) with PRP-supplemented media to culture in matching 3-dimensional (3D) PRP hydrogels. Cell proliferation, cell shape, and the pattern of gene and protein expression were examined. Our data revealed modifications in cell shape and enhanced expression of tenomodulin and scleraxis in 3D hydrogels. Additionally, protein secretion analysis using glass-based arrays specific for angiogenesis revealed differences in interleukin (IL)-6 and IL-8 protein expression between 2D cultures and 3D hydrogels, while the secretion of other angiogenic or inflammatory cytokines was unaffected. Our study suggests that 3D hydrogels are physiologically more relevant than 2D cultures in the study of tendon cells, based on cell shape, support of tenocyte proliferation, phenotype, and the pattern of gene and protein expression.

Emerging drugs for the treatment of knee osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is the most prevailing form of joint disease, with symptoms affecting 10 - 12% of the adult population with a projection of a 50% increase in prevalence in the next two decades. The disease characteristics are defined by articular cartilage damage, low-grade synovial inflammation and hypertrophic bone changes, leading to pain and functional deterioration. To date, available pain treatments are limited in their efficacy and have associated toxicities. No structural disease modification agents have been approved by regulatory agencies for this indication.

AREAS COVERED

We reviewed drugs in Phase II - III for OA pain and joint structure modification. Different aspects of structure modification are divided into targets of inflammatory pathway, cartilage catabolism and anabolism, and subchondral bone remodeling.

EXPERT OPINION

Further insight into the pathophysiology of the disease will allow for development of novel target classes focusing on the link between symptomatology and structural changes. Given the complexity of OA, one single therapy is unlikely to be universally and uniformly effective. Promising therapies are under development, but there are obstacles in the translation of treatment from preclinical models and trial designs need to be cognizant of the complex reasons for previous trial failures.