Effect of Autologous Expanded Bone Marrow Mesenchymal Stem Cells or Leukocyte-Poor Platelet-Rich Plasma in Chronic Patellar Tendinopathy (With Gap >3 mm): Preliminary Outcomes After 6 Months of a Double-Blind, Randomized, Prospective Study

Autologous bone marrow derived mesenchymal stem cells are safe for the treatment of Achilles tendinopathy

Achilles tendinopathy is a disabling condition that affects more than 50% of runners. Pre-clinical studies in a large animal model of naturally-occurring tendinopathy similar to human Achilles tendinopathy has shown benefits of autologous bone marrow-derived mesenchymal stem cell (MSC) implantation. However, MSCs are advanced therapies medicinal products (ATMPs), with strict regulatory requirements. Guided by the regulator we carried out a first in man study to assess the safety and efficacy of autologous MSC injection in human patients with non-insertional Achilles tendinopathy. Ten patients, mean age 47 with mid-portion Achilles tendon pain and swelling for more than 6 months, underwent autologous cultured cell injections (median 12.2 × 106, range 5-19 × 106 cells) into their Achilles tendon. At 24 weeks follow-up, no serious adverse reactions or important medical events were observed. MOXFQ, EQ-5D-5L, and VISA-A scores improved clinically at 12 and 24 weeks. VAS pain improved increasingly at 6, 12 and 24 weeks. MOXFQ Pain and VISA-A Scores improved > 12 points from baseline to 24 weeks in 8 patients. Maximum anteroposterior tendon thickness as measured by greyscale US decreased by mean 0.8 mm at 24 weeks. This phase IIa study demonstrated the safety of autologous MSC injection for non-insertional Achilles tendinopathy and provides proof-of-concept of the technique in patients, all of whom had previously failed conservative treatments for chronic disease and leads the way for a larger randomised controlled trial.

Results of Randomized Controlled Trials of Platelet-Rich Plasma in Lower-Extremity Tendinopathy Are Not Influenced by Industry Sponsorship

PURPOSE

To determine whether industry affiliation influences the results of randomized controlled trials (RCTs) studying the use of platelet-rich plasma (PRP) for the treatment of patellar or Achilles tendinopathy.

METHODS

The PubMed, Scopus, Cochrane, and MEDLINE databases were searched in July 2023 for RCTs investigating PRP for the treatment of patellar or Achilles tendinopathy published between 2009 and July 2023. Industry affiliation was determined by analyzing each study's funding or conflict-of-interest section. Author disclosures were searched in the American Academy of Orthopaedic Surgeons disclosure database and the Centers for Medicare & Medicaid Services open payments database. An industry-affiliated (IA) designation was given if an author had a relevant disclosure or if the company that funded the study manufactured PRP. Otherwise, a non-industry-affiliated (NIA) designation was given. Fisher exact analysis was used to determine whether PRP had a favorable effect, no significant effect, or an unfavorable effect on outcome.

RESULTS

Analysis was performed on 22 studies (10 IA and 12 NIA), with 17 studies (77.3%) reporting a conflict of interest or funding for the research, 4 (18.2%) reporting no conflict of interest, and 1 (4.5%) with no reporting. Of the 22 included studies, 8 (36.4%) reported favorable outcomes regarding PRP use and 14 (63.6%) reported no significant effect. Favorable outcomes were found in 4 of the 10 IA studies (40.0%), whereas no significant effect was reported in 6 (60.0%). The 12 NIA studies included 4 (33.3%) with favorable results and 8 (66.7%) with no significant effect. The comparison between industry affiliation and results reported was not statistically significant (P > .999).

CONCLUSIONS

The results of RCTs evaluating the use of PRP in lower-extremity tendinopathy were not influenced by industry sponsorship.

CLINICAL RELEVANCE

Most biomedical research is funded through industry sponsorship. Although this relation is necessary as technologies are developed, it is important to scrutinize studies for evidence of industry bias to understand how this bias may be affecting study results published in the literature.

The Use of Platelet-Rich Plasma and Stem Cell Injections in Musculoskeletal Injuries

Injuries to the musculoskeletal (MSK) system can have a significant impact on an individual's activities of daily living, as this multifunctional unit is associated with physical movement. Treatment of MSK injuries often involves corticosteroid injections, supplements, pharmaceutical agents, and/or surgery. While these approaches have been shown to be effective for some patients over both the short and long term, they can be associated with limited relief, adverse effects, and/or decreases in activities of daily living. An unmet need exists to develop and/or implement more effective treatment approaches for MSK injuries. Treatment options being explored include platelet-rich plasma (PRP) and stem cell injections. This review outlines the current state of research evaluating PRP and stem cell injections in the treatment of various MSK injuries. A literature search was conducted using the PubMed database to identify the relevant published articles related to the use of PRP and/or stem cell injections for the treatment of MSK and cartilage injuries. PRP and stem cell injections have been shown to improve an individual's quality of life (QOL) and are associated with fewer side effects as compared to invasive standards of care in multiple MSK injuries such as plantar fasciitis, Achilles tendinopathy, acute muscle and tendon tears, ligament injuries, chondral and medial collateral ligament (MCL) knee injuries and arthritis, rotator cuff lesions, and avascular femoral necrosis. Specifically, these studies on PRP and stem cell injections suggest that both approaches are associated with a quicker return to activities of daily living while providing longer lasting relief without significant adverse events. The studies reviewed demonstrated PRP and stem cell approaches to be effective and safe for the treatment of certain MSK injuries, but as standardized protocols were not utilized across studies in the discussion of similar injuries, it was therefore difficult to compare their efficacy and safety. As such, further research is warranted to establish standardized research protocols across MSK injury studies to gain further insight into the efficacy, safety, and durability of PRP and stem cell injections.

Most Orthopaedic Platelet-Rich Plasma Investigations Don't Report Protocols and Composition: An Updated Systematic Review

PURPOSE

To systematically review the literature to assess the heterogeneity of platelet-rich plasma (PRP) preparation and composition reporting for the treatment of musculoskeletal/orthopaedic pathologies.

METHODS

A systematic review was performed by searching PubMed, the Cochrane Library, and Embase to identify Level I and Level II studies from 2016 to 2022 that evaluated the use of PRP therapy for musculoskeletal pathologies. The search phrase used was "platelet-rich plasma clinical studies." Studies were assessed based on their reporting of the PRP preparation methods and reporting of PRP composition.

RESULTS

One hundred twenty-four studies (in 120 articles) met inclusion criteria for analysis. Of these studies, 15 (12.1%) provided comprehensive reporting, including a clear, well-described, and reproducible preparation protocol that future investigators can follow. Thirty-three studies (26.6%) quantitatively reported the final PRP product composition.

CONCLUSIONS

Among the studies using PRP for the treatment of musculoskeletal/orthopaedic pathologies, less than 20% provided a clear, well-described, and reproducible PRP preparation protocol, and only one-fourth of studies reported on the final PRP product composition.

CLINICAL RELEVANCE

A diverse current reporting of PRP composition between studies provides a high heterogeneity of the term "PRP," which becomes a limitation for a comparison of studies using PRP.

Treatment of Tendon Injuries in the Servicemember Population across the Spectrum of Pathology: From Exosomes to Bioinductive Scaffolds

Tendon injuries in military servicemembers are one of the most commonly treated nonbattle musculoskeletal injuries (NBMSKIs). Commonly the result of demanding physical training, repetitive loading, and frequent exposures to austere conditions, tendon injuries represent a conspicuous threat to operational readiness. Tendon healing involves a complex sequence between stages of inflammation, proliferation, and remodeling cycles, but the regenerated tissue can be biomechanically inferior to the native tendon. Chemical and mechanical signaling pathways aid tendon healing by employing growth factors, cytokines, and inflammatory responses. Exosome-based therapy, particularly using adipose-derived stem cells (ASCs), offers a prominent cell-free treatment, promoting tendon repair and altering mRNA expression. However, each of these approaches is not without limitations. Future advances in tendon tissue engineering involving magnetic stimulation and gene therapy offer non-invasive, targeted approaches for improved tissue engineering. Ongoing research aims to translate these therapies into effective clinical solutions capable of maximizing operational readiness and warfighter lethality.

Advances in mesenchymal stem cells therapy for tendinopathies

Tendinopathies are chronic diseases of an unknown etiology and associated with inflammation. Mesenchymal stem cells (MSCs) have emerged as a viable therapeutic option to combat the pathological progression of tendinopathies, not only because of their potential for multidirectional differentiation and self-renewal, but also their excellent immunomodulatory properties. The immunomodulatory effects of MSCs are increasingly being recognized as playing a crucial role in the treatment of tendinopathies, with MSCs being pivotal in regulating the inflammatory microenvironment by modulating the immune response, ultimately contributing to improved tissue repair. This review will discuss the current knowledge regarding the application of MSCs in tendinopathy treatments through the modulation of the immune response.

Management of Patellar Tendinopathy

Patellar tendinopathy is a common pathology typically seen in athletes involved in repetitive explosive jumping and running activities. Also known as jumpers' knee, it is commonly seen in high-level basketball players. Typically, athletes continue to play with symptoms, which can be aggravated and progress to partial patellar tendon tears. When partial patellar tendon tears occur, prolonged recovery and decreased performance is commonly seen. The pathology and treatment can be frustrating for both the athlete and medical provider. Patellar tendinopathy typically does not involve inflammation but rather microinjury to the tendon fibers, which leads to mucoid degeneration, necrosis, and loss of transitional fibrocartilage. When partial tendon tears do occur, the typical location is posteromedially adjacent to the patella. Treatment involves a stepwise approach starting with nonoperative means, including activity modification, nonsteroidal anti-inflammatories, and physical therapy focused on eccentrics. Extracorporeal shock wave treatments and injections with platelet-rich plasma or bone marrow aspirate concentrate should be considered, with evolving literature to support their use. Ultrasound percutaneous tendon scrapping with a needle supplemented with the aforementioned injections is an emerging treatment option that the authors have found to be helpful, although further studies are required. Surgical intervention is considered after failure of nonoperative treatments, and typically occurs in tears greater than 50% of the tendon thickness and in tendons with increased thickness (>8.8 mm). Open or arthroscopic debridement can be considered, with no studies showing superior outcomes with either technique; however, no high-quality comparison studies exist. The authors prefer an open technique where, much like a bone-patellar tendon-bone harvest, the unhealthy proximal tendon and bone are excised with then closure of the healthy tendon with absorbable sutures. Suture anchor repair may also be used when necessary. In a recent systematic review, surgical management of patellar tendinopathy has been shown to result in improved patient-reported outcomes with return to sport at high levels.1 Treatment for the difficult and sometimes frustrating pathology of patellar tendinopathy continues to evolve, with biologic and less-invasive ultrasound-based treatments showing promise, and surgical intervention providing reliable outcomes.

Platelet Concentrates Preconditioning of Mesenchymal Stem Cells and Combined Therapies: Integrating Regenerative Strategies for Enhanced Clinical Applications

This article presents a comprehensive review of the factors influencing the efficacy of mesenchymal stem cells (MSCs) transplantation and its association with platelet concentrates (PCs). It focuses on investigating the impact of PCs' composition, the age and health status of platelet donors, application methods, and environmental factors on the outcomes of relevant treatments. In addition, it delves into the strategies and mechanisms for optimizing MSCs transplantation with PCs, encompassing preconditioning and combined therapies. Furthermore, it provides an in-depth exploration of the signaling pathways and proteomic characteristics associated with preconditioning and emphasizes the efficacy and specific effects of combined therapy. The article also introduces the latest advancements in the application of biomaterials for optimizing regenerative medical strategies, stimulating scholarly discourse on this subject. Through this comprehensive review, the primary goal is to facilitate a more profound comprehension of the factors influencing treatment outcomes, as well as the strategies and mechanisms for optimizing MSCs transplantation and the application of biomaterials in regenerative medicine, offering theoretical guidance and practical references for related research and clinical practice.

Safety and Efficacy of Bone Marrow-Derived Mesenchymal Stem Cells for Chronic Patellar Tendinopathy (With Gap >3 mm) in Patients: 12-Month Follow-up Results of a Phase 1/2 Clinical Trial

Background

In a previous study, the authors found that at 6 months after treatment with a 20 × 106 dose of bone marrow-derived mesenchymal stem cells (BM-MSCs), patients showed improved tendon structure and regeneration of the gap area when compared with treatment using leukocyte-poor platelet-rich plasma (Lp-PRP). The Lp-PRP group (n = 10), which had not seen tendon regeneration at the 6-month follow-up, was subsequently offered treatment with BM-MSCs to see if structural changes would occur. In addition, the 12-month follow-up outcomes of the original BM-MSC group (n = 10) were evaluated.

Purpose

To evaluate the outcomes of all patients (n = 20) at 12 months after BM-MSC treatment and observe if the Lp-PRP pretreated group experienced any type of advantage.

Study Design

Cohort study; Level of evidence, 2.

Methods

Both the BM-MSC and original Lp-PRP groups were assessed at 12 months after BM-MSC treatment with clinical examination, the visual analog scale (VAS) for pain during daily activities and sports activities, the Victorian Institute of Sport Assessment-Patella score for patellar tendinopathy, dynamometry, and magnetic resonance imaging (MRI). Differences between the 2 groups were compared with the Student t test.

Results

The 10 patients originally treated with BM-MSCs continued to show improvement in tendon structure in their MRI scans (P < .0001), as well as in the clinical assessment of their pain by means of scales (P < .05). Ten patients who were originally treated with Lp-PRP and then with BM-MSCs exhibited an improvement in tendon structure in their MRI scans, as well as a clinical pain improvement, but this was not significant on the VAS for sports (P = .139). Thus, applying Lp-PRP before BM-MScs did not yield any type of advantage.

Conclusion

The 12-month follow-up outcomes after both groups of patients (n = 20) received BM-MSC treatment indicated that biological treatment was safe, there were no adverse effects, and the participants showed a highly statistically significant clinical improvement (P < .0002), as well as an improvement in tendon structure on MRI (P < .0001). Preinjection of Lp-PRP yielded no advantages.

Current Concepts in Patellar Tendinopathy: An Overview of Imaging, Pathogenesis, and Nonoperative and Operative Management

» Approximately 1 in 3 high-impact athletes develops patellar tendinopathy (PT), with the proximal insertion of the patellar tendon being the most commonly affected anatomical site.» Nonoperative treatment options are effective in reducing pain and restoring functionality in most patients with PT. However, operative intervention should be considered when conservative management fails.» A comprehensive review of the literature on surgical procedures, including both open and arthroscopic approaches, was conducted with a specific focus on clinical outcomes and return to sports.» Both open surgery and arthroscopic surgery for PT have demonstrated favorable success rates and return-to-sport outcomes, with arthroscopic treatment potentially expediting the recovery process.

3D-printed hydrogel particles containing PRP laden with TDSCs promote tendon repair in a rat model of tendinopathy

Long-term chronic inflammation after Achilles tendon injury is critical for tendinopathy. Platelet-rich plasma (PRP) injection, which is a common method for treating tendinopathy, has positive effects on tendon repair. In addition, tendon-derived stem cells (TDSCs), which are stem cells located in tendons, play a major role in maintaining tissue homeostasis and postinjury repair. In this study, injectable gelatine methacryloyl (GelMA) microparticles containing PRP laden with TDSCs (PRP-TDSC-GM) were prepared by a projection-based 3D bioprinting technique. Our results showed that PRP-TDSC-GM could promote tendon differentiation in TDSCs and reduce the inflammatory response by downregulating the PI3K-AKT pathway, thus promoting the structural and functional repair of tendons in vivo.

Intra-articular injection of bone marrow aspirate concentrate (BMAC) or adipose-derived stem cells (ADSCs) for knee osteoarthritis: a prospective comparative clinical trial

BACKGROUND

We determined whether autologous mesenchymal stem cells (MSCs) injections provide clinical and functional improvements in knee osteoarthritis (KOA) patients, and whether the results differ between autologous bone marrow cells (BMAC) and adipose-derived stromal cells (ADSCs).

METHODS

Between January 2021 and April 2022, 51 patients undergoing intra-articular injection of BMAC and 51 patients undergoing intra-articular injection of ADSCs were prospectively recruited. The Kellgren and Lawrence (K-L) classification was used to grade the severity of osteoarthritis. Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), and visual analog scale (VAS) were collected for all 102 patients in the previous week before the procedures, and at the one and 6 months from injection.

RESULTS

Knee KOOS scores, knee OKS scores, and VAS pain scores changed in similar ways in the two treatment groups. Both treatment groups demonstrated significant improvement pre-procedure to post-procedure in knee KOOS scores (p < 0.0001), knee OKS scores (p < 0.0001), and VAS pain scores (p < 0.0001). Patients with K-L grade 2 showed better functional and clinical outcomes than patients with K-L grades 3 and 4 (p < 0.0001).

CONCLUSION

Both intra-articular BMAC and ADSC injections significantly improved pain and functional outcomes at 6-month follow-up in patients with KOA. The difference between BMAC and ADCSs groups as tissue sources of MSCs was not statistically significant in terms of clinical and functional outcomes.

Orthobiologics: Current Status in 2023 and Future Outlook

Orthobiologic agents, including platelet-rich plasma, connective tissue progenitor cells derived from bone marrow, adipose, and other tissues, and purified cytokines and small peptides, have tremendous potential to target deficiencies in soft-tissue healing. The principal limitation currently is the variability in the composition and biologic activity of orthobiologic formulations, making it difficult to choose the optimal treatment for a specific tissue or pathology. Current data suggest that orthobiologics are "symptom-modifying," but there is little evidence that they can lead to true tissue regeneration ("structure-modifying"). A critically important need at this time is to identify sentinel markers of potency and biologic activity for different orthobiologic formulations so that we can match the treatment to the desired biologic effect for a specific tissue or pathology. Improved understanding of the underlying cellular and molecular mechanisms of tissue degeneration and repair will allow a precision medicine approach where we can choose the optimal orthobiologic treatment of specific orthopaedic problems. It is important for the clinician to be aware of the evolving regulatory status of orthobiologic treatments. Emerging therapies such as the use of exosomes and gene therapy approaches hold great promise as improved methods to both treat symptoms and affect tissue regeneration.

The Efficiency and Safety of Platelet-Rich Plasma Dressing in the Treatment of Chronic Wounds: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Recently, many clinical trials have applied platelet-rich plasma (PRP) dressings to treat wounds that have stopped healing, which are also called chronic wounds. However, the clinical efficiency of PRP dressings in treating chronic wounds is still controversial. Therefore, we conducted this study to compare PRP dressings with normal saline dressings in treating chronic wounds. Relevant randomized controlled trials focusing on utilizing PRP dressings in treating chronic wounds were extracted from bibliographic databases. Finally, 330 patients with chronic wounds, reported in eight randomized controlled trials, were included in this study. In total, 169 out of 330 (51.21%) were treated with PRP dressings, and 161 out of 330 (48.79%) were treated with normal saline dressings. The pooled results showed that the complete healing rate of the PRP group was significantly higher than that of saline group at 8 weeks and 12 weeks, respectively. In addition, there were no significant differences in wound infection and adverse events. Compared with normal saline dressing, the PRP dressing could effectively enhance the prognosis of chronic wounds. Furthermore, the PRP did not increase wound infection rate or occurrence of adverse events as an available treatment for chronic wounds.

Tendon appearance at imaging may be altered, but it may not indicate pathology

Both in tendon repair following a tear and in tendinopathy, recovery from pain and restoration of (acceptable) function does not go hand in hand with the appearance of the affected tendon at imaging. The tendon may remain altered for a long while and possibly forever, indicating a possible dissociation between morphology and symptoms. The predictive value of asymptomatic abnormal findings remains limited, and interventions in such instances are inappropriate and not supported by current evidence. Once an initial imaging investigation has depicted the condition of the tendon, additional imaging investigations are unlikely to provide further information or change prognosis in patients in whom abnormalities compatible with a diagnosis of tendinopathy have been identified by either ultrasonography or MRI. Patient education and close clinical monitoring are recommended. This is applicable to the patellar tendon, Achilles tendon, rotator cuff, for both tendon repair and tendinopathy. Given the modest risk of sonographic abnormalities to develop in symptomatic tendinopathy, planning and trying to implement any form of intervention may not be warranted. The current evidence mostly arises from low-quality studies, with heterogeneous risk factors and populations, and caution must be maintained when interpreting the significance of such incidental findings in athletes.

Efficacy of Platelet-Rich Plasma Versus Placebo in the Treatment of Tendinopathy: A Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To evaluate the efficacy of platelet-rich plasma (PRP) injections versus placebo in the treatment of tendinopathy.

DATA SOURCES

We performed a systematic literature search in MEDLINE, Embase, Scopus, CINAHL, Cochrane Library, and ClinicalTrials.gov through November 2020 to identify randomized controlled trials (RCTs) that evaluated the clinical efficacy of PRP versus placebo for the treatment of tendinopathy. Outcomes were analyzed on an intention-to-treat basis with random-effects models.

MAIN RESULTS

A total of 13 RCTs were included in this meta-analysis. The pooled analysis showed no significant difference in pain relief at 4 to 6 weeks (standard mean difference [SMD]: -0.18, 95% confidence intervals [CI]: -0.62 to 0.26), 12 weeks (SMD: -0.14, 95% CI: -0.55 to 0.26), and ≥24 weeks (SMD: -0.56, 95% CI: -1.16 to 0.05) or function improvement at 4 to 6 weeks (SMD: 0.11, 95% CI: -0.13 to 0.35), 12 weeks (SMD: 0.18, 95% CI: -0.13 to 0.49), and ≥24 weeks (SMD: 0.26, 95% CI: -0.14 to 0.66) for PRP compared with placebo in the treatment of tendinopathy. The sensitivity analysis indicated no significant difference in pain relief or function improvement at 12 weeks between PRP and placebo for different types of tendinopathies, treatment regimens, leukocyte concentrations, or cointerventions.

CONCLUSIONS

Platelet-rich plasma injection was not found to be superior to placebo in the treatment of tendinopathy, as measured by pain relief and functional improvement at 4 to 6, 12, and ≥24 weeks.

Platelet-rich plasma injection in the treatment of patellar tendinopathy: a systematic review and meta-analysis

Purpose

The objective of the study was to assess the efficacy of autologous platelet-rich plasma (PRP) injections in the treatment of patellar tendinopathy.

Methods

The PubMed, MEDLINE, EMBASE, CINAHL, and Cochrane Central Register of Controlled Trials databases were searched for clinical trials which compared PRP injection with other ‘active treatment’ interventions (‘Non-PRP’ injection and ‘No-injection’ treatments) or ‘No-active treatment’ interventions. Randomized and non-randomized clinical trials that had been published up to 15 November 2021, were included in the meta-analysis. The primary outcome, pain relief, was measured on a ‘visual analog scale.’ Secondary outcomes were knee functional activities and quality of life (QoL). The PRISMA guidelines were followed throughout the study.

Results

Eight comparative studies were identified for inclusion in the meta-analysis. Assessment of these studies revealed that there were no significant differences in pain relief, functional outcomes, and QoL in the short, medium, and long term between PRP injection and Non-PRP injection interventions. Similarly, comparison of PRP injection to the No-active treatment intervention showed no differences in short- and medium-term pain relief. However, when PRP injection was compared to the No-injection treatment intervention extracorporeal shock wave therapy (ECWT), the former was found to be more effective in terms of pain relief in the medium term (mean difference [MD] − 1.50; 95% confidence interval [CI] − 2.72 to − 0.28) and long term (MD − 1.70; 95% CI, − 2.90 to − 0.50) and functional outcomes in the medium term (MD 13.0; 95% CI 3.01–22.99) and long term (MD 13.70; 95% CI 4.62–22.78).

Conclusions

In terms of pain relief and functional outcomes, the PRP injection did not provide significantly greater clinical benefit than Non-PRP injections in the treatment of patellar tendinopathy. However, in comparison with ESWT, there was a significant benefit in favor of PRP injection.

Cell therapy efficacy and safety in treating tendon disorders: a systemic review of clinical studies

Purpose

Despite substantial animal evidence, cell therapy in humans remains in its infancy. The purpose of this study was to examine the potential therapeutic effects and safety of cell therapy in the treatment of tendon disorders.

Methods

According to the PRISMA guideline, a systematic review was performed on clinical studies concerning cell therapy in tendon disorders. A comprehensive search including the 5 databases of MEDLINE, Embase, Scopus, Web of Science, and Cochrane Library until December 2021 was carried out and associated with hand searching. The quality of the eligible studies was assessed using the tools suggested by Cochrane recommendations. Qualitative synthesis was performed in 2 tables and discussed separately for rotator cuff, elbow, patella, Achilles, and gluteal tendons.

Results

Through 6017 records, 22 studies were included in the qualitative synthesis, including 658 patients. All the studies administered autologous cells, except one that used allogenic adipose-derived mesenchymal stem cells (Allogenic AD-MSC). Almost all studies demonstrated the safety of cell injection in their follow-up period with no serious side effects or immunologic reactions, with only a few related minor adverse events in some cases.

The included studies showed the effectiveness of cell injection in tendinopathies of different sites, rotator cuff, elbow, patella, Achilles, and gluteal tendons. Among the rotator cuff studies, 4 comparative studies claimed that cell therapy is a more efficient treatment with a lower retear rate and pain level compared to the control group. However, one study found no differences between the groups. No controlled study has been performed on elbow tendinopathies, but 5 case series demonstrated the effectiveness of cell injection in elbow tendon disorders. For Achilles tendinopathies, only one randomized controlled trial (RCT) found that both cell therapy and control groups showed significant pain reduction and functional improvement with no statistical differences at the 6 months follow-up, but the cell therapy group had improved faster at earlier follow-ups. Patellar tendinopathy was studied in 2 RCTs, one did not show a significant difference and the other showed superior improvement compared to controls.

Conclusion

Cell therapy showed promising results and the available evidence suggests that it is safe at several sites of tendon disease. Based on available evidence, cell therapy should be suggested in specific conditions at each site. To approve cell therapy for tendon diseases, randomized clinical trials are required with a large sample size and long-term follow-ups.

Level of evidence

IV

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00520-9.

Knee Extensor Mechanism Tendinopathy: Evaluation, Treatment, and Prevention

ABSTRACT

Knee extensor mechanism tendinopathy, including patellar and quadriceps tendinopathy, is common among athletes and those involved in jumping sports. It is largely a clinical diagnosis that presents as anterior knee pain and stiffness with associated tenderness over the affected tendon. Imaging modalities, including ultrasound and/or magnetic resonance imaging, may be helpful with the diagnosis of difficult cases or in the planning of interventional procedures. Focused and structured rehabilitation using eccentric or heavy slow resistance exercise in conjunction with load management is important for recovery. Adjuvant therapies (e.g., injections or surgery) may be necessary in recalcitrant cases or those with insufficient response to rehabilitation efforts. Prevention strategies focus on improving biomechanics, landing mechanism and lower-extremity balance, flexibility, and strength.

Application of Orthobiologics in Achilles Tendinopathy: A Review

Orthobiologics are biological materials that are intended for the regeneration of bone, cartilage, and soft tissues. In this review, we discuss the application of orthobiologics in Achilles tendinopathy, more specifically. We explain the concepts and definitions of each orthobiologic and the literature regarding its use in tendon disorders. The biological potential of these materials can be harnessed and administered into injured tissues, particularly in areas where standard healing is disrupted, a typical feature of Achilles tendinopathy. These products contain a wide variety of cell populations, cytokines, and growth factors, which have been shown to modulate many other cells at local and distal sites in the body. Collectively, they can shift the state of escalated inflammation and degeneration to reestablish tissue homeostasis. The typical features of Achilles tendinopathy are failed healing responses, persistent inflammation, and predominant catabolic reactions. Therefore, the application of orthobiologic tools represents a viable solution, considering their demonstrated efficacy, safety, and relatively easy manipulation. Perhaps a synergistic approach regarding the combination of these orthobiologics may promote more significant clinical outcomes rather than individual application. Although numerous optimistic results have been registered in the literature, additional studies and clinical trials are still highly desired to further illuminate the clinical utility and efficacy of these therapeutic strategies in the management of tendinopathies.

Patellar Tendinopathy: Critical Analysis Review of Current Nonoperative Treatments

»

Patellar tendinopathy is an attritional injury of the patellar tendon that is frequently identified in jumping athletes. Through repetitive or explosive movements, considerable loads and high peak strains are generated across the patellar tendon.

»

This leads to microinjury of tendon fibers, local mucoid degeneration, and loss of the fibrocartilaginous tissue that attaches tendon to bone.

»

Management of patellar tendinopathy often begins with nonoperative modalities: progressive tendon loading and eccentric rehabilitative exercise programs are the most effective. While a variety of additional treatment modalities are available, the comparative efficacy of these supportive treatments is not well differentiated at this time.

»

In this article, we analyze the existing literature regarding nonoperative treatment of patellar tendinopathy and provide additional insight on the effectiveness of current modalities.

Management of patellar tendinopathy: a systematic review and network meta-analysis of randomised studies

Objectives

We performed a systematic review and network meta-analysis (NMA) of randomised controlled trials (RCTs) to provide insights into the effectiveness of available treatment modalities in patellar tendinopathy(PT).

Methods

Several databases were searched in May 2021 for RCTs assessing the effectiveness of any intervention compared with any other intervention, placebo or no treatment for pain and/or function in PT. The risk of bias and strength of evidence were assessed with the Cochrane Collaboration and GRADE (Grading of Recommendations, Assessment, Development and Evaluations)/GRADE-NMA tools.

Results

A total of 37 RCTs were eligible that assessed 33 different interventions and their combinations, most represented by single studies. Based on pairwise meta-analyses of two RCTs, extracorporeal shockwave therapy (ESWT) does not appear to be superior to sham ESWT (eccentric exercise in both groups) for short-term pain (mean differences (MD) +0.1, 95% CI (−0.8 to 1), p=0.84) or function (MD −1.8, 95% CI (–8 to 4.4), p=0.57). Based on a pairwise meta-analysis of three RCTs, isometric exercise appears as effective as isotonic exercise for immediate postintervention pain relief (MD −1.03, 95% CI (−2.6 to 0.5), p=0.19). Our NMA showed that topical glyceryl trinitrate (GTN) and hyaluronic acid injection, both combined with eccentric exercise and moderate, slow resistance exercise had the highest probability of being the most effective interventions (low/very low strength of evidence).

Conclusions

Promising interventions with inadequate evidence, such as topical GTN, hyaluronic acid injections and isometric and slow resistance exercise, should be further investigated through high-quality RCTs. Meanwhile, eccentric loading with or without adjuncts should remain the first-line treatment for all individuals with patellar tendinopathy.

Cell-Based Therapies for the Treatment of Shoulder and Elbow Tendinopathies: A Scoping Review

Introduction

Tendinopathies are a common cause of disability among the general population, and their management is challenging due to the degenerative nature of these disorders. The aim of this paper is to perform a scoping review of the available clinical evidence on the application of cell-based therapies for the management of elbow and rotator cuff tendinopathies, in order to summarize the current application methods and to shed light on the therapeutic potential and current limitations of these biologic approaches.

Materials and Methods

A scoping review of the literature was performed on the PubMed and Scopus databases using the following inclusion criteria: clinical reports of any level of evidence, written in English, with no time limitation, on the use of cell-based approaches to treat rotator cuff or elbow tendinopathies, including studies on biological augmentation during the surgical procedure. Exclusion criteria were as follows: case reports or mini case series (<5 patients), articles not written in English, and reviews. Relevant data were then extracted and collected in a single database with the consensus of the two observers to be analyzed for the purposes of the present manuscript.

Results

Seven papers dealing with rotator cuff tears were included. Four of them investigated the effect of injections, either MSCs alone or in combination with PRP, whereas three studies investigated the use of MSCs in combination with surgery. In all cases, an improvement was found in terms of clinical scores, with even evidence of tendon healing documented at second-look arthroscopy. Six papers dealt with elbow tendinopathies: three studies described the use of MSCs either with or without surgery, reporting significant clinical improvement and three studies analyzed the use of different types of cells (collagen-producing cells and autologous tenocytes) and, even in this case, clinical improvement was reported.

Conclusion

All the papers included suggested a beneficial role of cell-based approaches to treat common upper limb tendinopathies, with an overall satisfactory safety profile. However, the lack of high-level evidence and the presence of controversial issues, such as interproduct variability, harvest source, and application strategies, do not allow standardization of these novel biologic approaches, whose efficacy needs to be confirmed with properly designed randomized trials.