Does Platelet-Rich Plasma Lead to Earlier Return to Sport When Compared With Conservative Treatment in Acute Muscle Injuries? A Systematic Review and Meta-analysis

The Role of Platelet-Rich Plasma Injection for Muscle Strains in Athletes

Muscle tears/strains are among the most common musculoskeletal injuries, posing a serious challenge for sports medicine. Aiming to reduce the time to return to play and the rate of reinjuries, apart from the traditional conservative treatments and rehabilitation protocols, new and innovative therapeutic options have emerged, particularly platelet-rich plasma (PRP). This study aims to present the available evidence regarding PRP injection for the treatment of muscle strains in athletes. Two databases were searched for articles published between January 2012 and December 2022 in Portuguese or English. The query used for the PubMed database was ("Muscles/injuries"[Mesh]) AND ("Athletes"[Mesh] OR "Athletic Injuries"[Mesh]) AND "Platelet-Rich Plasma"[Mesh], while for the Web of Science database the search was performed for "Platelet-rich plasma" AND "Muscle injuries" AND ("Athletes" OR "Athletic injuries"). Eleven studies involving athletes diagnosed with muscle injuries who received treatment with PRP injection alone, or in combination with traditional conservative treatment, compared to a control group, were included. Four randomized controlled trials, four systematic reviews/meta-analyses, two retrospective studies, and one comparative study were included. Current evidence from the highest-quality studies does not support the hypothesis of reduction of time to return to play and the rate of reinjuries after PRP injection, even though some studies reported positive results. However, the available evidence suggests that PRP might have a beneficial effect on the pain perceived by athletes following an acute muscle strain. It is challenging to arrive at definitive conclusions and translate these findings into a clinical context for treating muscle strains in athletes. The existing trials present several inconsistencies and limitations, with a heterogeneous set of patients and injuries, as well as the use of different and inconsistent methods for preparing, administering, and measuring the effects of PRP. To achieve consistent outcomes, standardizing PRP administration procedures is essential.

Percutaneous Interventions for Injuries in Athletes: Implications on Return to Play

For nonsurgical musculoskeletal (MSK) injuries in athletes, image-guided percutaneous intervention may aid in recovery and decrease return to play (RTP) time. These interventions fall into two major categories: to reduce inflammation (and therefore alleviate pain) or to promote healing. This review describes the risks and benefits of the various percutaneous interventions in MSK athletic injury and surveys the literature regarding the implication of these interventions on RTP.

Hamstring Injuries: A Current Concepts Review: Evaluation, Nonoperative Treatment, and Surgical Decision Making

The purpose of this current concepts review is to highlight the evaluation and workup of hamstring injuries, nonoperative treatment options, and surgical decision-making based on patient presentation and injury patterns. Hamstring injuries, which are becoming increasingly recognized, affect professional and recreational athletes alike, commonly occurring after forceful eccentric contraction mechanisms. Injuries occur in the proximal tendon at the ischial tuberosity, in the muscle belly substance, or in the distal tendon insertion on the tibia or fibula. Patients may present with ecchymoses, pain, and weakness. Magnetic resonance imaging remains the gold standard for diagnosis and may help guide treatment. Treatment is dictated by the specific tendon(s) injured, tear location, severity, and chronicity. Many hamstring injuries can be successfully managed with nonoperative measures such as activity modification and physical therapy; adjuncts such as platelet-rich plasma injections are currently being investigated. Operative treatment of proximal hamstring injuries, including endoscopic or open approaches, is traditionally reserved for 2-tendon injuries with >2 cm of retraction, 3-tendon injuries, or injuries that do not improve with 6 months of nonoperative management. Acute surgical treatment of proximal hamstring injuries tends to be favorable. Distal hamstring injuries may initially be managed nonoperatively, although biceps femoris injuries are frequently managed surgically, and return to sport may be faster for semitendinosus injuries treated acutely with excision or tendon stripping in high-level athletes.

Leukocyte-poor platelet-rich plasma and leukocyte-rich platelet-rich plasma promote myoblast proliferation through the upregulation of cyclin A, cdk1, and cdk2

Muscle injuries are common among athletes and often treated with platelet-rich plasma (PRP). However, whether the leukocyte concentration affects the efficacy of PRP in treating muscle injuries remains unclear. This study investigated the effects of leukocyte-poor platelet-rich plasma (LP-PRP) and leukocyte-rich platelet-rich plasma (LR-PRP) on myoblast proliferation and the molecular mechanisms underlying these effects. Myoblasts were treated with 0.5% LP-PRP, 0.5% LR-PRP, 1% LP-PRP, or 1% LR-PRP for 24 h. The gene expression of the LP-PRP- and LR-PRP-treated myoblasts was determined using RNA sequencing analysis. Cell proliferation was evaluated using an bromodeoxyuridine (BrdU) assay, and cell cycle progression was assessed through flow cytometry. The expression of cyclin A, cyclin-dependent kinase 1 (cdk1), and cdk2 was examined using Western blotting. The expression of myoblast determination protein 1 (MyoD1) was examined through Western blotting and immunofluorescence staining. The LP-PRP and LR-PRP both promoted the proliferation of myoblasts and increased differential gene expression of myoblasts. Moreover, the LP-PRP and LR-PRP substantially upregulated the expression of cyclin A, cdk1, and cdk2. MyoD1 expression was induced in the LP-PRP and LR-PRP-treated myoblasts. Our results corroborate the finding that LP-PRP and LR-PRP have similar positive effects on myoblast proliferation and MyoD1 expression.

Utilizing Extracorporeal Shockwave Therapy for in-Season Athletes

An athlete’s health and availability to train and compete at an optimal performance level is a growing focus for professional sports organizations [...]

Lower Extremity Muscle Injuries in the Overhead Athlete

PURPOSE OF REVIEW

Lower extremity (LE) injuries are a common source of disability and time-loss for overhead athletes, and muscles have been found to be the predominant soft tissue structure affected. The current review highlights the orthopaedic literature examining lower extremity muscle injuries in overhead athletes in regard to epidemiology, diagnosis, and conventional and emerging treatment measures.

RECENT FINDINGS

The hamstring muscles have been found to be the most commonly injured lower extremity muscle group in professional baseball, followed by the adductors, quadriceps, iliopsoas, and gastrocnemius-soleus complex. Strains and contusions comprise over 90% of these muscle injuries. Various advanced imaging grading systems have been developed to help characterize the nature of a muscle injury, although a clear and consistent prognostic utility of these systems is still unclear. The vast majority of lower extremity muscle injuries in overhead athletes are managed nonoperatively, and there is promising data on the use of emerging treatments such as platelet-rich plasma and blood flow restriction therapy. Lower extremity muscle injuries-often referred to as strains-are a relatively common issue in high-demand overhead athletes and can be a significant source of time-loss. Within baseball, position players are affected far more often than pitchers, and sprinting and fielding are the most common activities leading to strains. Magnetic resonance imaging (MRI) is considered the gold standard imaging modality to evaluate these muscle injuries and will allow for a detailed assessment of tissue damage. Nonetheless, return-to-play is often dictated by a given athlete's progression through a nonoperative rehabilitation protocol, with surgical intervention reserved for less common, select injury patterns.

Prevention of Physical Risk and Rehabilitation of Muscle Injury in Sanda Competition

The Target. The purpose of this study is to explore the reduction of sports injury risk and verify the effective methods and means of athlete's muscle injury rehabilitation. Methods. In this study, 80 sanda athletes from a university were randomly selected as subjects, and the main parts of injury of all subjects were counted. After 12 weeks of muscle injury rehabilitation intervention, the pain, acute injury, and technical and tactical evaluation levels of subjects in the intervention group and the control group were compared. Results/Discussion. The overall performance of the 80 subjects' basic exercise ability was at a moderate level, and there was no significant difference between male and female subjects (P >0.05). After 12 weeks of rehabilitation intervention, there was no significant difference in the scores of shoulder joint flexibility, supine straight leg raising, and trunk stable support between male and female subjects in the intervention group in more than 7 sports (P >0.05). In the control group, there were significant differences in the scores of shoulder flexibility and trunk stability of male and female subjects (P < 0.05). Future research should further explore the effect of muscle injury rehabilitation on effectively reducing potential sports injuries and introduce advanced and effective medical rehabilitation methods.

Human Platelet-Rich Plasma Facilitates Angiogenesis to Restore Impaired Uterine Environments with Asherman’s Syndrome for Embryo Implantation and Following Pregnancy in Mice

Asherman’s syndrome (AS) is caused by intrauterine adhesions and inactive endometrium from repeated curettage of the uterine endometrium. AS is a major cause of recurrent implantation failure and miscarriage and is very difficult to treat because of the poor recovery of endometrial basal cells. Platelet-rich plasma (PRP) has abundant growth factors that may induce angiogenesis and cell proliferation. Here, we demonstrate that human PRP (hPRP) significantly enhances angiogenesis to restore embryo implantation, leading to successful pregnancy in mice with AS. In mice with AS, hPRP treatment considerably reduced the expression of fibrosis markers and alleviated oligo/amenorrhea phenotypes. Mice with AS did not produce any pups, but the hPRP therapy restored their infertility. AS-induced abnormalities, such as aberrantly delayed embryo implantation and intrauterine growth retardation, were considerably eliminated by hPRP. Furthermore, hPRP significantly promoted not only the elevation of various angiogenic factors, but also the migration of endometrial stromal cells. It also increased the phosphorylation of STAT3, a critical mediator of wound healing, and the expression of tissue remodeling genes in a fibrotic uterus. PRP could be a promising therapeutic strategy to promote angiogenesis and reduce fibrosis in impaired uterine environments, leading to successful embryo implantation for better clinical outcomes in patients with AS.

Calf Strain in Athletes

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Calf strain is a common condition. In high-performance athletes, calf strain contributes to a substantial absence from competition.

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Player age and history of a calf strain or other leg injury are the strongest risk factors for calf strain injury and reinjury.

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Although the diagnosis is often clinical, magnetic resonance imaging and ultrasound are valuable to confirm the location of the strain and the grade of injury.

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Nonoperative treatment is effective for most calf strain injuries. Operative management, although rarely indicated, may be appropriate for severe cases with grade-III rupture or complications.

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Further investigation is necessary to elucidate the benefits of blood flow restriction therapy, deep water running, lower-body positive pressure therapy, platelet-rich plasma, and stem cell therapy for calf strain rehabilitation.

The Biological Use of Platelet-Rich Plasma in Skeletal Muscle Injury and Repair

Platelet-rich plasma (PRP) is a blood product that contains several growth factors and active proteins. PRP is thought to be used autologously to assist in the repair of injured tissues as well as to treat pain at the site of injury. The mechanism behind PRP in regenerative medicine has been well investigated and includes the identification and concentration of released growth factors and exosomes. The benefits of PRP have been highly recommended and are used widely in orthopaedics and sports medicine, including repair of injured skeletal muscle. This current report summarizes some of the more recent studies in the use of PRP as it relates to muscle healing, in both the in vitro and clinical arenas.

Evidence-Based Management and Factors Associated With Return to Play After Acute Hamstring Injury in Athletes: A Systematic Review

Background:

Considering the lengthy recovery and high recurrence risk after a hamstring injury, effective rehabilitation and accurate prognosis are fundamental to timely and safe return to play (RTP) for athletes.

Purpose:

To analyze methods of rehabilitation for acute proximal and muscular hamstring injuries and summarize prognostic factors associated with RTP.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

In August 2020, MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials, and SPORTDiscus were queried for studies examining management and factors affecting RTP after acute hamstring injury. Included were randomized controlled trials, cohort studies, case-control studies, and case series appraising treatment effects on RTP, reinjury rate, strength, flexibility, hamstrings-to-quadriceps ratio, or functional assessment, as well as studies associating clinical and magnetic resonance imaging factors with RTP. Risk of bias was assessed using the Cochrane Risk-of-Bias Tool for Randomized Trials or the Methodological Index for Non-Randomized Studies (MINORS).

Results:

Of 1289 identified articles, 75 were included. The comparative and noncomparative studies earned MINORS scores of 18.8 ± 1.3 and 11.4 ± 3.4, respectively, and 12 of the 17 randomized controlled trials exhibited low risk of bias. Collectively, studies of muscular injury included younger patients and a greater proportion of male athletes compared with studies of proximal injury. Surgery for proximal hamstring ruptures achieved superior outcomes to nonoperative treatment, whereas physiotherapy incorporating eccentric training, progressive agility, and trunk stabilization restored function and hastened RTP after muscular injuries. Platelet-rich plasma injection for muscular injury yielded inconsistent results. The following initial clinical findings were associated with delayed RTP: greater passive knee extension of the uninjured leg, greater knee extension peak torque angle, biceps femoris injury, greater pain at injury and initial examination, “popping” sound, bruising, and pain on resisted knee flexion. Imaging factors associated with delayed RTP included magnetic resonance imaging-positive injury, longer lesion relative to patient height, greater muscle/tendon involvement, complete central tendon or myotendinous junction rupture, and greater number of muscles injured.

Conclusion:

Surgery enabled earlier RTP and improved strength and flexibility for proximal hamstring injuries, while muscular injuries were effectively managed nonoperatively. Rehabilitation and athlete expectations may be managed by considering several suitable prognostic factors derived from initial clinical and imaging examination.

Use of Platelet-Rich Plasma Plus Suramin, an Antifibrotic Agent, to Improve Muscle Healing After Injuries

BACKGROUND

The increasing use of platelet-rich plasma (PRP) to treat muscle injuries raises concerns because transforming growth factor-beta (TGF-β) in PRP may promote fibrosis in the injured muscle and thus impair muscle regeneration.

PURPOSE

To investigate whether suramin (a TGF-β inhibitor) can reduce muscle fibrosis to improve healing of the injured muscle after PRP treatment and identify the underlying molecular mechanism.

STUDY DESIGN

Controlled laboratory study.

METHODS

Myoblasts isolated from the gastrocnemius muscle of Sprague Dawley rats were treated with PRP or PRP plus suramin. MTT assays were performed to evaluate cell viability. The expression of fibrosis-associated proteins (such as type I collagen and fibronectin), Smad2, and phosphorylated Smad2 was determined using Western blot analysis and immunofluorescent staining. An anti-TGF-β antibody was employed to verify the role of TGF-β in fibronectin expression. Gastrocnemius muscles were injured through a partial transverse incision and then treated using PRP or PRP plus suramin. Hematoxylin and eosin staining was conducted to evaluate the healing process 7 days after the injury. Immunofluorescent staining was performed to evaluate fibronectin expression. Muscle contractile properties-fast-twitch and tetanic strength-were evaluated through electric stimulation.

RESULTS

PRP plus 25 μg/mL of suramin promoted myoblast proliferation. PRP induced fibronectin expression in myoblasts, but suramin reduced this upregulation. The anti-TGF-β antibody also reduced the upregulation of fibronectin expression in the presence of PRP. The upregulation of phosphorylated Smad2 by PRP was reduced by either the anti-TGF-β antibody or suramin. In the animal study, no significant difference was discovered in muscle healing between the PRP versus PRP plus suramin groups. However, the PRP plus suramin group had reduced fibronectin expression at the injury site. Fast-twitch strength and tetanic strength were significantly higher in the injured muscle treated using PRP or PRP plus suramin.

CONCLUSION

Simultaneous PRP and suramin use reduced fibrosis in the injured muscle and promoted healing without negatively affecting the muscle's contractile properties. The underlying molecular mechanism may be associated with the phosphorylated Smad2 pathway.

CLINICAL RELEVANCE

Simultaneous PRP and suramin use may reduce muscle fibrosis without compromising muscle contractile properties and thus improve muscle healing.

Platelet-rich plasma: a narrative review

The aim of this article was to synopsize platelet-rich plasma (PRP) use in musculoskeletal pathologies through evidence-based assessment of the preparation, classification, mechanism of action and applications of PRP, thereby answering which PRP type is best for each clinical indication.

The literature search was performed using Medline, EMBASE and Cochrane Reviews databases for papers containing the key terms “platelet-rich plasma” AND “orthopaedics” AND (“classification” OR “mechanism of action” OR “preparation” OR “clinical application”). Generated papers were evaluated for pertinence in following areas: preparation, classification, mechanism of action, clinical application within orthopaedics. Non-English papers were excluded. Included studies were evaluated for quality.

Sixty studies were included in our review. There are many commercial PRP preparation kits with differing component concentrations. There is no consensus on optimal component concentrations. Multiple PRP classifications exist but none have been validated. Platelet-rich plasma acts via growth factors (GFs) released from α-granules within platelets. Growth factors have been shown to be beneficial in healing. Grossly elevated concentrations of GFs may have inhibitory effects on healing. Multiple systematic reviews show efficacy of PRP in tendinopathies, early osteoarthritis, acute muscle injuries and in combination with rotator cuff repair and anterior cruciate ligament reconstruction.

The literature suggests leukocyte-rich PRP (L-PRP) is more beneficial in tendinopathies and pure PRP (P-PRP) is more beneficial in cartilage pathology. However, different PRP preparations have not been directly compared in any pathology. Classification of PRP type is frequently not stated in research. Standardization of PRP research parameters is needed to streamline findings and generate clear indications for PRP types to yield maximum clinical benefit.

Cite this article: EFORT Open Rev 2021;6:225-235. DOI: 10.1302/2058-5241.6.200017

Platelet-Rich Plasma Injection for the Treatment of Hamstring Injuries: A Systematic Review and Meta-analysis With Best-Worst Case Analysis

BACKGROUND

Hamstring injuries are common and account for considerable time lost to play in athletes. Platelet-rich plasma has potential as a means to accelerate healing of these injuries.

PURPOSE

(1) To present the evidence of platelet-rich plasma injection in the treatment of hamstring injuries, (2) evaluate the "best-case scenario" in dichotomous outcomes, and (3) evaluate the "worst-case scenario" in dichotomous outcomes.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

Two authors systematically reviewed the PubMed, Embase, and Cochrane Library databases according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, with any discrepancies resolved by mutual consensus. The level of evidence was assessed per the criteria of the Oxford Centre for Evidence-Based Medicine and the quality of evidence by the Coleman Methodology Score. Meta-analysis by fixed effects models was used if heterogeneity was low (I² < 25%) and random effects models if heterogeneity was moderate to high (I²≥ 25%). P values <.05 were considered statistically significant.

RESULTS

A total of 10 studies were included with 207 hamstring injuries in the platelet-rich plasma group and 149 in the control group. Random-effects model for mean time to return to play that compared platelet-rich plasma + physical therapy to physical therapy alone non-significantly favored platelet-rich plasma + physical therapy (mean difference, -5.67 days). The fixed effects model for reinjury rates, which also compared platelet-rich plasma + physical therapy with physical therapy alone nonsignificantly favored platelet-rich plasma + physical therapy (risk ratio, 0.88). The best-case scenario fixed effects model for reinjury rates nonsignificantly favored platelet-rich plasma + physical therapy (risk ratio, 0.82). The worst-case scenario fixed effects model for reinjury rates nonsignificantly favored physical therapy alone (risk ratio, 1.13). The mean ± SD complication rate for either postinjection discomfort, pain, or sciatic nerve irritation was 5.2% ± 2.9% (range, 2.7% to 9.1%).

CONCLUSION

There has been statistically nonsignificant evidence to suggest that PRP injection ± PT reduced mean time to RTP or reinjury rates compared to no treatment or PT alone for hamstring injuries in a short-term follow-up. The complication profiles were favorable. Further studies of high quality and large cohorts are needed to better support or disprove the consensus of the systematic review and meta-analysis.

PRP in wound healing applications

Platelets play a crucial role in hemostasis, tissue regeneration and host defense. Based on these settings, platelet-rich plasma (PRP) and its derivatives are therapeutically used to promote wound healing in several scenarios. This review summarizes the biological mechanisms underlying the most traditional as well as innovative applications of PRP in wound healing. These mechanisms involve the combined action of platelet-derived growth factors and cytokines, together with the role of plasma-derived fibrillar, antioxidant and homeostatic factors. In addition, regenerative treatments with PRP consist of personalized and non-standardized methods. Thus, the quality of PRP varies depending on endogenous factors (e.g., age; gender; concomitant medication; disease-associated systemic factors; nutrition) and exogenous factors (anticoagulants and cellular composition). This review also analyses whether these factors affect the biological mechanisms of PRP in wound healing applications.

Hamstring muscle injury in the athlete: state of the art

Hamstring injuries (HSI) are the source of significant impairment and disability for both professional and recreational athletes. The incidence and prevalence of HSIs has been well documented in the literature, as they are among the most common soft tissue injuries reported. The significant time loss due to injury and the inherent risk of reinjury pose a significant issue to the athlete, their career longevity and the success of their respective team. This review will deal predominantly with describing the prevalence and incidence of HSI in athletes, discuss risk factors and the mechanisms of injury for HSI, how to properly diagnose, image and prognosticate appropriate return to sport (RTS) for individuals who have sustained an HSI, prescribe treatment and prevention strategies and to discuss relevant options to decrease overall risk of primary and secondary recurrence of HSI.Current treatments of acute HSI necessitate a thorough understanding of the mechanism of injury, identifying muscle imbalances and/or weakness, inclusion of eccentric and concentric hamstring (HS) and hip extension (HE) exercises, evaluation of pathokinematic movement patterns and use non-surgical methods to promote healing and RTS. This methodology can be used prospectively to mitigate the overall risk of HSI. Injection therapies for HSI, including ultrasound-guided platelet-rich plasma and corticosteroids, may impart some short-term benefit, but the existing literature is largely inconclusive with respect to long-term functional outcomes. Future directions should prioritise injury prevention, early diagnosis and targeted interventions that combine both non-surgical and minimally invasive orthobiological approaches and identifying biomechanical risk factors prospectively to mitigate risk.

Gaelic Sport Injuries

The Gaelic sports of hurling and football, native to Ireland, are increasing in popularity worldwide. The injury profile of these sports requires multidisciplinary management by sports physicians, orthopaedic surgeons, and musculoskeletal (MSK) radiologists, among others. Advances in imaging modalities and interventional techniques have aided the diagnosis and treatment of sport injuries. In this article, we review the literature and our own institutional experience to describe common injury patterns identified in Gaelic games athletes, their main imaging features and relevant therapeutic interventions. We discuss the increasing prevalence of imaging services at sporting events and the central role of MSK radiologists in sports injury management.

Biological Basis of Treatments of Acute Muscle Injuries: A Short Review

Muscle strains occur frequently in recreational and professional sports. This article considers various treatment options in a biological context and reviews evidence of their efficacy. Treatments reviewed include the PRICE principle (P: rotection, R: est, I: ce, C: ompression, E: levation), early mobilization, physical therapy, hematoma aspiration, platelet-rich plasma injections, use of nonsteroidal anti-inflammatory drugs, corticosteroids, and local anesthetics, cellular therapies, and surgery.

Study protocol for a double-blind, randomised placebo-controlled trial evaluating clinical effects of platelet-rich plasma injection for acute grade-2 hamstring tear among high performance athletes

INTRODUCTION

Hamstring injury among athletes often results in significant morbidity. Currently, there are controversies regarding the clinical use of platelet-rich plasma (PRP) for the treatment of acute hamstring injury.

METHODS AND ANALYSIS

This study is a single-centre double-blind randomised placebo-controlled trial. Sixty-eight patients will be randomised to receive under ultrasound guidance either a single injection of leucocyte-rich PRP (LR-PRP) or normal saline. All patients will undergo a standardised hamstring rehabilitation programme under the supervision of a sports physiotherapist. Outcome data will be collected before intervention (baseline), and thereafter on a weekly basis. The primary outcome measure is the duration to return-to-play. It is defined as the duration (in days) from the date on which the injury occurred until the patients were pain-free, able to perform the active knee extension test and have regained hamstring muscle strength. Secondary outcome measures include assessment of pain intensity and the effect of pain on to day-to-day functions using the self-reported Brief Pain Inventory-Short Form questionnaire. Both the primary and secondary outcomes were assessed at baseline and thereafter once a week until return to play. Also, hamstring injury recurrence within the first 6 months after recovery will be monitored via telephone. The results of this study will provide insights into the effect of LR-PRP in muscle and may help to identify the best PRP application protocol for muscle injuries.

ETHICS AND DISSEMINATION

Ethics approval were obtained from the Medical Research Ethics Committee of the University of Malaya Medical Centre. Results of this trial will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ISRCTN76844299.

Novel Insights into the Pathogenesis of Spinal Sarcopenia and Related Therapeutic Approaches: A Narrative Review

Spinal sarcopenia is a complex and multifactorial disorder associated with a loss of strength, increased frailty, and increased risks of fractures and falls. In addition, spinal sarcopenia has been associated with lumbar spine disorders and osteoporosis, which renders making decisions on treatment modalities difficult. Patients with spinal sarcopenia typically exhibit lower cumulative survival, a higher risk of in-hospital complications, prolonged hospital stays, higher postoperative costs, and higher rates of blood transfusion after thoracolumbar spine surgery. Several studies have focused on the relationships between spinal sarcopenia, appendicular muscle mass, and bone-related problems-such as osteoporotic fractures and low bone mineral density-and malnutrition and vitamin D deficiency. Although several techniques are available for measuring sarcopenia, each of them has its advantages and shortcomings. For treating spinal sarcopenia, nutrition, physical therapy, and medication have been proven to be effective; regenerative therapeutic options seem to be promising owing to their repair and regeneration potential. Therefore, in this narrative review, we summarize the characteristics, detection methodologies, and treatment options for spinal sarcopenia, as well as its role in spinal disorders.

Platelet Concentrates in Musculoskeletal Medicine

Platelet concentrates (PCs), mostly represented by platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) are autologous biological blood-derived products that may combine plasma/platelet-derived bioactive components, together with fibrin-forming protein able to create a natural three-dimensional scaffold. These types of products are safely used in clinical applications due to the autologous-derived source and the minimally invasive application procedure. In this narrative review, we focus on three main topics concerning the use of platelet concentrate for treating musculoskeletal conditions: (a) the different procedures to prepare PCs, (b) the composition of PCs that is related to the type of methodological procedure adopted and (c) the clinical application in musculoskeletal medicine, efficacy and main limits of the different studies.

Platelet-rich plasma for sports-related muscle, tendon and ligament injuries: an umbrella review

BACKGROUND

Platelet-rich plasma (PRP) has been used in different non-transfusion indications due to its role in tissue regeneration and healing. The aim of this overview of systematic reviews (umbrella review) is to provide a summary of the existing research syntheses related to PRP use for sports-related muscle, tendon and ligament injuries.

MATERIALS AND METHODS

Literature searches were performed in MEDLINE, Embase, and Cochrane Library to identify systematic reviews focusing on PRP use for sports-related muscle, tendon and ligament injuries. The methodological quality of included studies was assessed using the checklist for systematic reviews and research syntheses developed by the Joanna Briggs Institute and the GRADE assessment.

RESULTS

Twenty-two studies met the inclusion criteria. Five studies evaluated PRP use for acute muscle injury, and 17 evaluated PRP use for tendon and ligament injury. Studies were heterogeneous in terms of the dose and number of PRP injections, and the control groups. Three of the 5 reviews evaluating acute muscle injury concluded that PRP had no effect on the outcomes considered. One review shows superior efficacy of rehabilitation exercise compared to PRP. One review shows that PRP may result in an earlier return to sport for acute grade I-II injury. Eight out of the 17 reviews evaluating PRP for tendon and ligament injuries show a statistically significant (p<0.05) difference in pain and/or function outcome measures favouring PRP compared to controls, although most of the observed differences were small. Adverse events data and quality of life outcomes were rarely analysed or reported in the included studies and were considered clinically insignificant.

DISCUSSION

In most of the included reviews, the available evidence was judged to be of low/very low quality due to risk of bias, inconsistency and imprecision, thus making the level of certainty of these findings low and not adequate to support the general use of PRP in this setting.

Hamstring Injuries in Athletes: Evidence-based Treatment

Hamstring injuries are common in athletes and can cause notable disability. They can be separated based on proximal, muscle belly, and distal injuries, with proximal and distal injuries more commonly requiring surgical intervention. Most injuries do not require acute MRI; however, MRI is useful in proximal and distal injuries as well as muscle belly tears that fail to respond to nonsurgical treatment. Acute repair of proximal avulsions, both partial and complete, result in successful outcomes, whereas chronic complete repairs are more difficult and less reliable. Muscle belly injuries have predictable outcomes but recurrence is common. Nonsurgical treatments focus on eccentric strengthening with the possible addition of low WBC platelet-rich plasma, which may have the potential to hasten recovery and decrease re-rupture. Distal injuries are relatively rare but may require surgical intervention. Hamstring reinjury is common, making continuation of preventive therapies after return to sport essential. Future research with larger sample sizes are required to determine how to decrease injury and reinjury rates, to evaluate the efficacy of platelet-rich plasma and to determine other treatments that may accelerate recovery after injury.

Efficacy of platelet-rich plasma for non-transfusion use: Overview of systematic reviews

INTRODUCTION

Platelet-rich plasma (PRP) is a blood component therapy with a supraphysiological concentration of platelets derived from allogenic or, more commonly, autologous blood. PRP has been used in different non-transfusion indications because of its role in the promotion of tissue repair and healing, in fields such as Traumatology, Dermatology and Dentistry.

OBJECTIVE

To provide a synthesis of the efficacy of PRP for different clinical situations.

METHODS

Systematic searches were carried out in MEDLINE, Embase, Cochrane Library and LILACS in July 2018 to identify systematic reviews (SRs) of randomized clinical trials (RCTs) focusing on PRP for non-transfusion use. Two authors independently screened all retrieved references in two stages (titles and abstracts at a first stage and full texts at a second stage). The methodological quality of SRs that met the eligibility criteria was appraised by AMSTAR 2. Conclusions were based on the most recent SRs with highest quality.

RESULTS

One thousand two hundred and forty references were retrieved. After checking the inclusion criteria, 29 SRs of RCTs related to three different fields (wound care, Orthopedics and Dentistry) were included. The results suggest the benefit of PRP for different clinical situations, such as diabetic wounds, acute lesions of musculoskeletal system, rotator cuff lesions, tendinopathies, knee and hip osteoarthritis, total knee arthroplasty, allogenic bone graft for dental implants and periodontal intrabony defects.

CONCLUSION

There is low to moderate quality evidence supporting the efficacy of PRP for specific clinical situations. The low quality of the evidence limits the certainty of these findings. Well-planned and well-conducted RCTs are still needed to further assess the efficacy of PRP.

Classification systems for platelet-rich plasma

There is good scientific rationale to support the use of growth factors to promote musculoskeletal tissue regeneration. However, the clinical effectiveness of platelet-rich plasma (PRP) and other blood-derived products has yet to be proven. Characterization and reporting of PRP preparation protocols utilized in clinical trials for the treatment of musculoskeletal disease is highly inconsistent, and the majority of studies do not provide sufficient information to allow the protocols to be reproduced. Furthermore, the reporting of blood-derived products in orthopaedics is limited by the multiple PRP classification systems available, which makes comparison of results between studies challenging. Several attempts have been made to characterize and classify PRP; however, no consensus has been reached, and there is lack of a comprehensive and validated classification. In this annotation, we outline existing systems used to classify preparations of PRP, highlighting their advantages and limitations. There remains a need for standardized universal nomenclature to describe biological therapies, as well as a comprehensive and reproducible classification system for autologous blood-derived products.

Cite this article: Bone Joint J 2019;101-B:891–896.

Influence of Platelet-Rich and Platelet-Poor Plasma on Endogenous Mechanisms of Skeletal Muscle Repair/Regeneration

The morpho-functional recovery of injured skeletal muscle still represents an unmet need. None of the therapeutic options so far adopted have proved to be resolutive. A current scientific challenge remains the identification of effective strategies improving the endogenous skeletal muscle regenerative program. Indeed, skeletal muscle tissue possesses an intrinsic remarkable regenerative capacity in response to injury, mainly thanks to the activity of a population of resident muscle progenitors called satellite cells, largely influenced by the dynamic interplay established with different molecular and cellular components of the surrounding niche/microenvironment. Other myogenic non-satellite cells, residing within muscle or recruited via circulation may contribute to post-natal muscle regeneration. Unfortunately, in the case of extended damage the tissue repair may become aberrant, giving rise to a maladaptive fibrotic scar or adipose tissue infiltration, mainly due to dysregulated activity of different muscle interstitial cells. In this context, plasma preparations, including Platelet-Rich Plasma (PRP) and more recently Platelet-Poor Plasma (PPP), have shown advantages and promising therapeutic perspectives. This review focuses on the contribution of these blood-derived products on repair/regeneration of damaged skeletal muscle, paying particular attention to the potential cellular targets and molecular mechanisms through which these products may exert their beneficial effects.

Treatment of Muscle Injuries with Platelet-Rich Plasma: a Review of the Literature

PURPOSE OF REVIEW

This review discusses the current literature regarding the use of platelet-rich plasma (PRP) in the treatment of muscle strain injuries. Case series as well as experimental trials for both human and animal models are covered.

RECENT FINDINGS

Multiple studies have examined outcomes for the use of PRP in the treatment of muscle strain injuries. PRP has been shown to promote muscle recovery via anabolic growth factors released from activated platelets, and in doing so, potentially reduces pain, swelling, and time for return to play. In vitro studies support the regenerative potential of PRP for acute soft tissue injuries. Multiple clinical case series for PRP injections in the setting of muscle strains demonstrate imaging evidence for faster healing, less swelling, which can decrease time for return to play. These studies, however, are retrospective in nature, and few randomized controlled studies exist to demonstrate a clear clinical benefit. Additionally, there is tremendous heterogeneity regarding the injectant preparation, optimum platelet concentration, presence of leukocytes, and volume of PRP which should be administered as well as number of and timing of treatments.

A contemporary view of platelet-rich plasma therapies: moving toward refined clinical protocols and precise indications

The positive extensive clinical experience with platelet-rich plasma (PRP) in different medical areas has prompted researchers to explore clinical opportunities for optimized PRP therapies. PRP is safe but we have to make it more effective. The growing diversity of formulations and presentations enrich the field of PRP research and offer hope to refine clinical indications. Moving toward targeting the right disease phenotypes with the right PRP formulation or combination product (PRP + cell products) can offer opportunities to change treatment options in osteoarthritis and nonhealing wounds. Both are active areas of research that could offer opportunities, although cost efficacy is still an open question. Our position is to believe that these serious disease areas are likely to benefit from PRP therapies.

Platelet-rich plasma and the shoulder: clinical indications and outcomes

PURPOSE OF REVIEW

The orthopedic community has seen a rapid rise in the clinical use of platelet-rich plasma (PRP) in the management of shoulder pathologies over the past decade. The purpose of this paper is to review the current literature regarding the indications and outcomes of PRP for the surgical and non-surgical management of common shoulder pathologies, including rotator cuff tears.

RECENT FINDINGS

Multiple studies have been published recently regarding the use of PRP for the operative and non-operative treatment of rotator cuff tears. There has been less research published on the use of PRP in the management of other conditions of the shoulder. Despite attempts to standardize and classify PRP formulations, there remains great variation in the inter- and intra-subjection composition, preparation, and administration techniques of PRP, limiting the conclusions that can be drawn regarding the utility and effectiveness of this biologic treatment as reported by Mazzocca et al. (J Bone Joint Surg Am. 94(4):308-16, 2012). Recent literature has shown equivocal to minor benefit of PRP use for shoulder pain, function, and healing. While few complications have been reported and PRP administration appears to carry little risk to the patient, the body of literature is currently inconclusive regarding the clinical benefit and cost-effectiveness of PRP in the treatment of shoulder pathology. As for PRP use specifically as an adjunct to surgical rotator cuff repairs, there is no clear consensus on its effectiveness in either clinical or structural outcomes. To further delineate the efficacy of PRP for shoulder pathology, it is essential that more double-blinded, randomized controlled investigations with large sample sizes and standardized PRP preparations be performed.

The use of platelets in regenerative medicine and proposal for a new classification system: guidance from the SSC of the ISTH

Autologous and single-donor allogenic platelet preparations are increasingly being used in many areas of regenerative medicine. However, there are few properly controlled randomized clinical trials, and the preparation, content and characteristics of platelet preparations are generally poorly defined and controlled. The Platelet Physiology Subcommittee of the Scientific and Standardization Committee (SSC) of the ISTH formed a working party of experts with the aim of producing consensus recommendations for guidance on the use of platelets in regenerative medicine. Owing to a lack of investigations that provide definitive evidence for the efficacy, definition and use of different platelet preparations in regenerative medicine, there were insufficient data to develop evidence-based guidelines. Therefore, the RAND method was used, which obtains a formal consensus among experts particularly when scientific evidence is absent, scarce and/or heterogeneous. Using this approach, each expert scored as 'appropriate', 'uncertain' or 'inappropriate' a series of 45 statements about the practice of regenerative medicine with platelets, which included different sections on general aspects, platelet preparations, clinical trial design, and potential utility in different clinical scenarios. After presentation and public discussion at SSC meetings, the assessments were further refined to produce final consensus recommendations, which constitute the subject of the present report.

Platelet-Rich Plasma Releasate Promotes Regeneration and Decreases Inflammation and Apoptosis of Injured Skeletal Muscle

BACKGROUND

Platelet-rich plasma (PRP) contains various cytokines and growth factors that may be beneficial to the healing process of injured muscle. Based on the authors' previous study, PRP releasate can promote proliferation and migration of skeletal muscle cells in vitro, so animal studies are performed to support the use of PRP to treat muscle injury in vivo.

PURPOSE

To investigate the effect of PRP releasate on regeneration of injured muscle, as well as its effect on inflammatory reaction and cell apoptosis, in the early stages of the muscle-healing process.

STUDY DESIGN

Controlled laboratory study.

METHODS

The gastrocnemius muscles of Sprague-Dawley rats were injured by partial transverse incision and then treated with PRP releasate. Hematoxylin and eosin stain was used to evaluate the healing process of injured muscle at 2, 5, and 10 days after injury. TUNEL assay was used to evaluate the cell apoptosis of injured muscle after PRP releasate treatment. Immunohistochemistry was used to stain the CD68-positive cells during the healing process. Muscle contractile properties, including fast-twitch and tetanic strength, were evaluated by electric stimulation.

RESULTS

The results revealed that PRP releasate treatment could enhance the muscle-healing process and decrease CD68-positive cells and apoptotic cells. Furthermore, the tetanic strength was significantly higher in injured muscle treated with PRP releasate.

CONCLUSION

In conclusion, PRP releasate could enhance the healing process of injured muscle and decrease inflammatory cell infiltration as well as cell apoptosis.

CLINICAL RELEVANCE

PRP promotes skeletal muscle healing in association with decreasing inflammation and apoptosis of injured skeletal muscle. These findings provide in vivo evidence to support the use of PRP to treat muscle injury.