Revolving doors of tendinopathy: definition, pathogenesis and treatment

Erroneous Differentiation of Tendon Stem/Progenitor Cells in the Pathogenesis of Tendinopathy: Current Evidence and Future Perspectives

Tendinopathy is a condition characterized by persistent tendon pain, structural damage, and compromised functionality. Presently, the treatment for tendinopathy remains a formidable challenge, partly because of its unclear pathogenesis. Tendon stem/progenitor cells (TSPCs) are essential for tendon homeostasis, regeneration, remodeling, and repair. An innovative theory has been previously proposed, with insufficient evidence, that the erroneous differentiation of TSPCs may constitute one of the fundamental mechanisms underpinning tendinopathy. Over the past few years, there has been accumulating evidence for plausibility of this theory. In this review, we delve into alterations in the differentiation potential of TSPCs and the underlying mechanisms in the context of injury-induced tendinopathy, diabetic tendinopathy, and age-related tendinopathy to provide updated evidence on the erroneous differentiation theory. Despite certain limitations inherent in the existing body of evidence, the erroneous differentiation theory emerges as a promising and highly pertinent avenue for understanding tendinopathy. In the future, advanced methodologies will be harnessed to further deepen comprehension of this theory, paving the way for prospective developments in clinical therapies targeting TSPCs for the management of tendinopathy.

Editorial Commentary: Platelet-Rich Plasma for Rotator Cuff Repair Improves Retear Rate but Clinical Impact Is Yet to Be Seen

Rotator cuff tendon repair has a high failure rate due to the inferior quality of tendon material. Platelet-rich plasma (PRP) is considered a potential solution, although its clinical impact is uncertain. Recent literature indicates that while PRP may reduce retear rates radiologically, it does not significantly improve clinical outcomes such as pain and function. Early animal studies showed potential benefits, but initial clinical trials were inconclusive due to small sample sizes and varied PRP methods. Larger, recent studies suggest a possible benefit, yet definitive clinical advantages remain elusive. Advancing PRP research requires a dual approach: deeper understanding of tendon and PRP biology, as well as larger clinical trials focusing on specific PRP preparations and delivery methods. While current evidence is limited, PRP holds promise for improving rotator cuff repair outcomes, and ongoing research may eventually translate into significant clinical benefits.

Bi-Exponential 3D UTE-T1ρ Relaxation Mapping of Ex Vivo Human Knee Patellar Tendon at 3T

Introduction: The objective of this study was to assess the bi-exponential relaxation times and fractions of the short and long components of the human patellar tendon ex vivo using three-dimensional ultrashort echo time T1ρ (3D UTE-T1ρ) imaging. Materials and Methods: Five cadaveric human knee specimens were scanned using a 3D UTE-T1ρ imaging sequence on a 3T MR scanner. A series of 3D UTE-T1ρ images were acquired and fitted using single-component and bi-component models. Single-component exponential fitting was performed to measure the UTE-T1ρ value of the patellar tendon. Bi-component analysis was performed to measure the short and long UTE-T1ρ values and fractions. Results: The single-component analysis showed a mean single-component UTE-T1ρ value of 8.4 ± 1.7 ms for the five knee patellar tendon samples. Improved fitting was achieved with bi-component analysis, which showed a mean short UTE-T1ρ value of 5.5 ± 0.8 ms with a fraction of 77.6 ± 4.8%, and a mean long UTE-T1ρ value of 27.4 ± 3.8 ms with a fraction of 22.4 ± 4.8%. Conclusion: The 3D UTE-T1ρ sequence can detect the single- and bi-exponential decay in the patellar tendon. Bi-component fitting was superior to single-component fitting.

Platelet-Rich Plasma Augmentation of Arthroscopic Rotator Cuff Repair Lowers Retear Rates and Improves Short-Term Postoperative Functional Outcome Scores: A Systematic Review of Meta-Analyses

Purpose

The purpose of this study is to conduct a systematic review of meta-analyses of rotator cuff repair using platelet-rich plasma (PRP) to identify whether PRP improves clinical function and rate of tendon retears. We will (1) conduct a systematic review of the current meta-analyses of rotator cuff repair using platelet-rich plasma available in the literature, (2) evaluate the quality of these meta-analyses using the Preferred Reporting Items for Systematic Review (PRISMA) methodology, (3) identify whether PRP improves clinical function and rate of tendon retears, and develop guidance to improve future studies in this area.

Methods

We carried out a systematic review of previous meta-analyses published on the clinical outcomes of PRP used in the treatment of rotator cuff tears. We performed a comprehensive search of PubMed, Medline, Cochrane, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and Embase databases, using various combinations of the commercial names of each PRP preparation and “rotator cuff” (with its associated terms), looking specifically at human meta-analysis studies involving the repair of the rotator cuff tendon surgically in the English language. Data validity was assessed and collected on clinical outcomes. Following this, a meta-analysis was undertaken.

Results

Thirteen meta-analyses met the inclusion and exclusion criteria. All were considered of similar quality with Oxman-Guyatt index of 9 and PRISMA score of more than 24. A total of 1,800 patients with an average follow up of 12 to 36 months. The use of PRP for arthroscopic rotator cuff tear, when compared with controls, leads to a lower number of retears, improved short-term postoperative scores, and functional outcome. The following postoperative scores were reported: Constant: 12, Simple Shoulder Test: 10, ASES (American Shoulder and Elbow Surgeons): 9, UCLA (University of California, Los Angeles) 11, SANE (Single Assessment Numeric Evaluation) 1, VAS (visual analog scale): 6, and Retears: 13. Subgroup analysis showed that leukocyte content and gel application make no difference in the effectiveness of PRP. VAS score subgroup analysis showed short-term pain relief.

Conclusions

Our study shows that PRP is effective in reducing retears after rotator cuff repair and improving functional outcome scores and reducing short-term pain.

Level of Evidence

Level III, systematic review of Level I-III studies.

Impact of Patellar Tendinopathy on Player Performance in the National Basketball Association

Background:

The extent to which patellar tendinopathy affects National Basketball Association (NBA) athletes has not been thoroughly elucidated.

Purpose:

To assess the impact patellar tendinopathy has on workload, player performance, and career longevity in NBA athletes.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

NBA players diagnosed with patellar tendinopathy between the 2000-2001 and 2018-2019 seasons were identified through publicly available data. Characteristics, return to play (RTP), player statistics, and workload data were compiled. The season of diagnosis was set as the index year, and the statistical analysis compared post- versus preindex data acutely and in the long term, both within the injured cohort and with a matched healthy NBA control cohort.

Results:

A total of 46 NBA athletes were included in the tendinopathy group; all 46 players returned to the NBA after their diagnosis. Compared with controls, the tendinopathy cohort had longer careers (10.50 ± 4.32 vs 7.18 ± 5.28 seasons; P < .001) and played more seasons after return from injury (4.26 ± 2.46 vs 2.58 ± 3.07 seasons; P = .001). Risk factors for patellar tendinopathy included increased workload before injury (games started, 45.83 ± 28.67 vs 25.01 ± 29.77; P < .001) and time played during the season (1951.21 ± 702.09 vs 1153.54 ± 851.05 minutes; P < .001) and during games (28.71 ± 6.81 vs 19.88 ± 9.36 minutes per game; P < .001). Players with increased productivity as measured by player efficiency rating (PER) were more likely to develop patellar tendinopathy compared with healthy controls (15.65 ± 4.30 vs 12.76 ± 5.27; P = .003). When comparing metrics from 1 year preinjury, there was a decrease in games started at 1 year postinjury (−12.42 ± 32.38 starts; P = .028) and total time played (−461.53 ± 751.42 minutes; P = .001); however, PER at 1 and 3 years after injury was unaffected compared with corresponding preinjury statistics.

Conclusion:

NBA players with a higher PER and significantly more playing time were more likely to be diagnosed with patellar tendinopathy. Player performance was not affected by the diagnosis of patellar tendinopathy, and athletes were able to RTP without any impact on career longevity.

[Tendinopathies of the Achilles tendon]

Disorders of the Achilles tendon are among the most frequent musculoskeletal injuries in athletes as well as in the general population. It is very important to differentiate the different clinical pictures summarized under the general term achillodynia and to understand the pathogenesis in order to undertake the correct therapeutic measures. In the case of insertional tendinopathies in particular, a rheumatological origin should be clarified. Doppler ultrasound is the most important diagnostic tool. Evidence-based treatment methods include various training programs, shock wave treatment, diverse injection and surgical procedures, each of which are discussed in detail in this article.

Lower Limb Tendinopathy Tissue Changes Assessed through Ultrasound: A Narrative Review

Tendinopathy is a common disease that affects athletes, causing pain and dysfunction to the afflicted tendon. A clinical diagnose is usually combined with imaging and, among all the existing techniques, ultrasound is widely adopted. The aim of this review is to sum up the existing evidence on ultrasound as an imaging tool and guide for treatments in lower limbs tendinopathy. Using three different databases—PubMed, MEDLINE and CENTRAL—a literature search has been performed in May 2020 combining MeSH terms and free terms with Boolean operators. Authors independently selected studies, conducted quality assessment, and extracted results. Ultrasound imaging has a good reliability in the differentiation between healthy and abnormal tendon tissue, while there are difficulties in the identification of tendinopathy stages. The main parameters considered by ultrasound imaging are tendon thickness, hypoechogenicity of tendon structure and neovascularization of the tendon bound tissue. Ultrasound-guide is also used in many tendinopathy treatments and the available studies gave encouraging results, even if further studies are needed in this field.