Comparison between platelet-rich plasma injections and hyaluronic acid injections in the treatment of patellar tendinopathies: a randomized 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

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

RESULTS

Analysis was done on 22 studies (10 IA and 12 NIA), with 17 (77.3%) studies 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 utilization and 14 (63.6%) reported no significant effect. Favorable outcomes were found in 4 (40.0%) of the 10 IA studies and 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 = 1).

CONCLUSION

Results of RCTs evaluating use of PRP on lower extremity tendinopathy were not influenced by industry sponsorship.

CLINICAL RELEVANCE

The majority of biomedical research is funded through industry sponsorship. While this relationship 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.

A Review of Patellar Tendinopathy in Athletes Involved in Jumping Sports

This review article discusses the anatomy and histopathology of the patellar tendon, as well as the risk factors and common interventions for patellar tendinopathy (PT) with a view to guide clinicians in treating athletes with patellar tendon pain. PT, or jumper's knee, refers to a chronic injury to the patellar tendon that affects athletes who engage in jumping and explosive movements. The condition is characterized by degeneration and disorganization of the collagen fibers in the tendon, an increase in mucoid ground substance, and fibroblast proliferation. Risk factors for patellar tendinopathy include participation in jumping sports, a greater counter-movement jump height, and training on hard surfaces. Nonoperative treatments for patellar tendinopathy include relative rest, stretching and strengthening exercises, and correction of biomechanical abnormalities. Surgery and other procedures, such as extracorporeal shockwave therapy (ESWT) and injection therapies, may be considered for patients who do not respond to conservative measures.

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.

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.

Assessment of the reporting quality of resistance training interventions in randomised controlled trials for lower limb tendinopathy: A systematic review

OBJECTIVES

1. To describe what exercises and intervention variables are used in resistance training interventions in randomised controlled trials for lower limb tendinopathy 2. To assess completeness of reporting as assessed by the Consensus on Exercise Reporting Template (CERT) and the Toigo and Boutellier framework. 3. To assess the implementation of scientific resistance training principles. 4. To assess therapeutic quality of exercise interventions with the i-CONTENT tool.

DATA SOURCES

We searched MEDLINE, CINAHL, AMED, EMBase, SPORTDiscus, and the Cochrane library databases.

REVIEW METHODS

Systematic review of randomised controlled trials that reported using resistance exercises for lower limb tendinopathies.

RESULTS

We included 109 RCTs. Eccentric heel drops were the most common exercise (43 studies), followed by isotonic heel raises (21), and single leg eccentric decline squats (18). Reporting of exercise descriptor items from the Toigo and Boutellier framework ranged from 0-13, with an average score of 9/13, and only 7 studies achieved a full 13/13. Reporting of items from the CERT ranged from 0-18, with an average score of 14/19. No study achieved a full 19/19, however 5 achieved 18/19. Scoring for resistance training principles ranged from 1-10, with only 11 studies achieving 10/10. Reporting across studies for the i-CONTENT tool ranged from 2-7, with an average score of 5 across included studies. A total of 19 studies achieved a full 7/7 score. Less than 50% of studies achieved an overall low risk of bias, highlighting the methodological concerns throughout studies.

CONCLUSION

The reporting of exercise descriptors and intervention content was generally high across RCTs for lower limb tendinopathy, with most allowing exercise replication. However, reporting for some tendinopathies and content items such as adherence was poor, limiting optimal translation to clinical practice.

Resistance Training Interventions for Lower Limb Tendinopathies: A Scoping Review of Resistance Training Reporting Content, Quality, and Scientific Implementation

The objectives of this scoping review were as follows: (1) to describe what exercises and intervention variables are used in resistance training interventions for lower limb tendinopathy,  (2) to assess the completeness of reporting as assessed by the Consensus on Exercise Reporting Template (CERT) and the Toigo and Boutellier framework, and (3) to assess the implementation of scientific resistance training principles. We searched MEDLINE, CINAHL, AMED, Embase, SPORTDiscus, and Cochrane Library databases. Randomized controlled trials, cohort studies, case series, case reports, and observational studies that reported using resistance exercises for lower limb tendinopathies were considered for inclusion, with 194 studies meeting the inclusion criteria. Completeness of the reporting of exercise descriptors and programme variables was assessed by the CERT and the Toigo and Boutellier framework. Reporting of exercise descriptor items from the Toigo and Boutellier framework ranged from 0 to 13, with an average score of 9/13, with only 9 studies achieving a full 13/13. Reporting of items from the CERT ranged from 0 to 18, with an average score of 13/19. No study achieved a full 19/19; however, 8 achieved 18/19. Scoring for resistance training principles ranged from 1 to 10, with only 14 studies achieving 10/10. Eccentric heel-drops were the most common exercise (75 studies), followed by isotonic heel raises (38), and single-leg eccentric decline squats (27). The reporting of exercise descriptors and intervention content was high across studies, with most allowing exercise replication, particularly for Achilles and patellar tendinopathy. However, reporting for some tendinopathies and content items such as adherence was poor, limiting optimal translation to clinical practice.

The Role of Hyaluronic Acid for Soft Tissue Indications: A Systematic Review and Meta-Analysis

CONTEXT

Soft tissue injuries are often treated with injectables such as corticosteroids and platelet-rich plasma (PRP) to reduce inflammation and promote healing. There is increasing evidence examining the use of hyaluronic acid (HA) for the management of soft tissue injuries.

OBJECTIVE

To evaluate the treatment effect and role of HA for available soft tissue indications.

DATA SOURCES

A search of PubMed, MEDLINE, EMBASE, and CENTRAL from the inception date of each database through February 24, 2021, was conducted for all randomized controlled trials (RCTs) involving the use of HA for soft tissue indications. Two reviewers independently screened articles for eligibility and extracted data from included studies for analysis. We assessed risk of bias for all included studies and pooled outcomes using a fixed-effects model. Outcomes (ie, function and pain relief) were categorized to short-term (<6 weeks, 6-12 weeks) and mid-term (>12 weeks) data. We present effect estimates as mean differences (MDs) and standardized mean differences (SMDs) and present the estimate of effect of HA for available indications in relation to available comparators.

STUDY DESIGN

Meta-analysis of RCTs.

LEVEL OF EVIDENCE

Level 1.

RESULTS

Of the 6930 articles screened, 19 RCTs (n = 1629 patients) were eligible and included in this review. HA was evaluated across a variety of soft tissue indications including rotator cuff disease, elbow pain, ankle sprains, Achilles tendinopathy, patellar tendinopathy, and trigger finger. Of the 19 RCTs, 11 were placebo-controlled and 9 used active comparators (PRP, cortisone, prolotherapy, or extracorporeal shockwave therapy). The pooled treatment effect of HA across most soft indications against placebo and active comparators demonstrated benefit in short-term pain <6 weeks (MD visual analogue scale [VAS] 2.48, 95% CI 2.31-2.65) and 6 to 12 weeks (MD VAS 2.03, 95% CI 1.86-2.20). Mid-term pain relief also favored HA over comparators across indications >12 weeks from administration (MD VAS 3.57, 95% CI 3.35-3.78). High heterogeneity was present with rotator cuff (10 trials, I² = 94%), and elbow tendinopathy (2 trials, I² = 99%). We identified uncertain benefit for trigger finger (2 trials, I² = 67%). Heterogeneity for ankle sprains, patellar tendinopathy and Achilles tendinopathy could not be assessed as they only had 1 trial each.

CONCLUSION

This systematic review and meta-analysis support HA's efficacy in the treatment of a variety of soft tissue indications. Understanding the relative effects of HA to other injectable modalities requires additional, large trials.

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.

The Impact of Hyaluronic Acid on Tendon Physiology and Its Clinical Application in Tendinopathies

The physical-chemical, structural, hydrodynamic, and biological properties of hyaluronic acid within tendons are still poorly investigated. Medical history and clinical applications of hyaluronic acid for tendinopathies are still debated. In general, the properties of hyaluronic acid depend on several factors including molecular weight. Several preclinical and clinical experiences show a good efficacy and safety profile of hyaluronic acid, despite the absence of consensus in the literature regarding the classification according to molecular weight. In in vitro and preclinical studies, hyaluronic acid has shown physical-chemical properties, such as biocompatibility, mucoadhesivity, hygroscopicity, and viscoelasticity, useful to contribute to tendon healing. Additionally, in clinical studies, hyaluronic acid has been used with promising results in different tendinopathies. In this narrative review, findings encourage the clinical application of HA in tendinopathies such as rotator cuff, epicondylitis, Achilles, and patellar tendinopathy.

Tendon Stem/Progenitor Cell Subpopulations and Their Implications in Tendon Biology

Tendon harbors a cell population that possesses stem cell characteristics such as clonogenicity, multipotency and self-renewal capacity, commonly referred to as tendon stem/progenitor cells (TSPCs). Various techniques have been employed to study how TSPCs are implicated in tendon development, homeostasis and healing. Recent advances in single-cell analysis have enabled much progress in identifying and characterizing distinct subpopulations of TSPCs, which provides a more comprehensive view of TSPCs function in tendon biology. Understanding the mechanisms of physiological and pathological processes regulated by TSPCs, especially a particular subpopulation, would greatly benefit treatment of diseased tendons. Here, we summarize the current scientific literature on the various subpopulations of TSPCs, and discuss how TSPCs can contribute to tissue homeostasis and pathogenesis, as well as examine the key modulatory signaling pathways that determine stem/progenitor cell state. A better understanding of the roles that TSPCs play in tendon biology may facilitate the development of novel treatment strategies for tendon diseases.