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The tendon-bone junction (TBJ), a critical transitional zone where tendons and bones connect, is particularly prone to injury due to the forces from muscle contractions and skeletal movements. Once tendon-bone injuries occur, the complex original tissue structure is difficult to restore, increasing the risk of re-tear. In this study, we initially established a rabbit model of tendon-bone injury and treated it using either interference screw or suture anchor. Biomechanical testing demonstrated the maximum tension and strength of TBJ with interference screw fixation were superior. However, histologic and immunohistochemical results showed more tissue regeneration and expression of cartilage markers at the site of injury with suture anchor fixation. Moreover, Gelatin Methacryloyl encapsulated with exosomes from mesenchymal stem cell (GelMA-exosomes) were prepared, showing a consistent and stable exosome release characteristic. The combined application of GelMA-exosomes with either interference screws or suture anchors further enhanced the healing of tendon-bone injuries, which may be achieved by promoting cellular proliferation as well as regulating the decreased expression of local pro-inflammatory factors IL-1β, IL-6 and TNF-α and increased expression of anti-inflammatory factors IL-10 and TGF-β. This provides a viable therapeutic strategy to enhance tendon-bone healing., Competing Interests: Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Objective: To investigate the anti-adhesive effect and underlying mechanism of dynamic and static stress stimulation on the early healing process of rat Achilles tendon injury., Methods: Achilles tendon tissues of 15 male Sprague Dawley (SD) rats aged 4-6 weeks were isolated and cultured by enzyme digestion method. Rat Achilles tendon cells were treated with tumor necrosis factor α to construct the Achilles tendon injury cell model, and dynamic stress stimulation (dynamic group) and static stress stimulation (static group) were applied respectively, while the control group was not treated. Live/dead cell double staining was used to detect cell activity, ELISA assay was used to detect the expression of α smooth muscle actin (α-SMA), and real-time fluorescence quantitative PCR was used to detect the mRNA expression of collagen type Ⅰ (COL1A1), collagen type Ⅲ (COL3A1), and Scleraxis (SCX). Thirty male SD rats aged 4-6 weeks underwent Achilles tendon suture and were randomly divided into dynamic group (treated by dynamic stress stimulation), static group (treated by static stress stimulation), and control group (untreated), with 10 rats in each group. HE staining and scoring were performed to evaluate the healing of Achilles tendon at 8 days after operation. COL1A1 and COL3A1 protein expressions were detected by immunohistochemical staining, α-SMA and SCX protein expressions were detected by Western blot, and maximum tendon breaking force and tendon stiffness were detected by biomechanical stretching test., Results: In vitro cell experiment, when compared to the static group, the number of living cells in the dynamic group was higher, the expression of α-SMA protein was decreased, the relative expression of COL3A1 mRNA was decreased, and the relative expression of SCX mRNA was increased, and the differences were all significant ( P <0.05). In the in vivo animal experiment, when compared to the static group, the tendon healing in the dynamic group was better, the HE staining score was lower, the expression of COL1A1 protein was increased, the expression of COL3A1 protein was decreased, the relative expression of SCX protein was increased, the relative expression of α-SMA protein was decreased, and the tendon stiffness was increased, the differences were all significant ( P <0.05)., Conclusion: Compared with static stress stimulation, the dynamic stress stimulation improves the fibrosis of the scar tissue of the rat Achilles tendon, promote the recovery of the biomechanical property of the Achilles tendon, and has obvious anti-adhesion effect.

Introduction: Tendon injuries present a significant challenge for independent repair, and can progress into tendinopathy over time, highlighting the importance of early intervention. Dendritic cell-derived exosomes (DEXs) has been shown to shift the polarization of M1 macrophages, the predominant inflammatory cells in the early stages of tendon injury. This study introduces a therapeutic approach that effectively manages inflammation while promoting regeneration in the treatment of tendinopathy., Methods: The purification and characterization of DEXs were meticulously conducted. Experiments were carried out using an Achilles tendon rupture mouse model, with weekly DEXs treatment starting on postoperative day (POD) 4. In vitro, the function of DEXs was assessed by coculturing them with tendon stem/progenitor cells (TSPCs) in culture medium containing IL-1β. Tendon healing progress was evaluated using Sirius Red staining, Masson's trichrome staining, biomechanical testing, and immunofluorescence microscopy. The inflammatory microenvironment of injured tendons was evaluated using the Luminex procedure and flow cytometry analysis., Results: DEXs treatment significantly enhanced tendon cell differentiation, promoted collagen type I synthesis, and inhibited collagen type III synthesis, thereby expediting tendon healing. Furthermore, DEXs treatment improved the inflammatory microenvironment by reducing multiple cytokines (IL-1β, IL-4, IL-6, TNF-α, and IFN-γ) and induced the conversion of M1 macrophages to M2 macrophages by activating the PI3K/AKT pathway., Conclusion: DEXs demonstrated a potent ability to promote tendon healing while ameliorating the inflammatory microenvironment, suggesting their potential as a therapeutic approach to prevent the development of tendinopathy., Competing Interests: The authors declare that they have no competing interests in this work., (© 2024 Chen et al.)

» Platelet-rich plasma and hyaluronic acid are low-risk and potentially high-reward treatments for Achilles tendinopathy, although clinical studies have yielded mixed results with questionable methodological quality» Case series and reports have reported that bone marrow aspirate, stem cells, and amniotic membrane products can improve functional outcomes, alleviate pain, and facilitate return to sport and activities, but high-level evidence studies are lacking» Exosomes are a promising novel biologic with laboratory studies showing improved collagen organization and cell proliferation, greater tendon mechanical properties, and prevention of extracellular matrix breakdown.» Standardization of protocols with clear reporting is necessary for future studies evaluating orthobiologic therapies for Achilles tendon injuries., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSREV/B170)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Degenerative tendinopathy results from the accumulation of minor injuries following unsuccessful tendon repair during acute tendon injuries. The process of tendon repair is prolonged and varies between individuals, making it susceptible to reinjury. Moreover, treating chronic tendinopathy often requires expensive and extensive rehabilitation, along with a variety of combined therapies to facilitate recovery. This condition significantly affects the quality of life of affected individuals, underscoring the urgent need for more efficient and cost-effective treatment options. Although traditional treatments have improved significantly and are being used as substitutes for surgical interventions, the findings have been inconsistent and conflicting. This review aims to clarify these issues by exploring the strengths and limitations of current treatments as well as recent innovations in managing various forms of degenerative tendinopathy.

Partial or complete rupture of the tendon can damage the collagen structure, resulting in the disruption of the electrical signal pathway. It is a great challenge to reconstruct the original electrical signal pathway of the tendon and promote the regeneration and functional recovery of defective tendon. In this study, carbon fiber-mediated electrospinning scaffolds were fabricated by wrapping conductive, high-strength, loose single-bundle carbon fibers with nanofiber membranes. Due to the presence of nanofiber membranes, the maximum tensile force of the scaffolds was 2.4 times higher than that of carbon fibers, while providing excellent temporal and spatial prerequisites for tenocytes to adapt to electrical stimulation to accelerate proliferation and expression. The diameter of the carbon fiber monofilaments used in this study was 5.07 ± 1.20 μm, which matched the diameter of tendon collagen, allowing for quickly establishing the connection between the tendon tissue and the scaffold, and better promoting the recovery of the electrical signal pathway. In a rabbit Achilles tendon defect repair model, the carbon fiber-mediated electrospinning scaffold was almost filled with collagen fibers compared to a nonconductive polyethylene glycol terephthalate scaffold. Transcriptome sequencing revealed that fibromodulin and tenomodulin expression were upregulated, and their related proteoglycans and glycosaminoglycan binding proteins pathways were enhanced, which could regulate the TGF-β signaling pathway and optimize the extracellular matrix assembly, thus promoting tendon repair. Therefore, the scaffold in this study makes up for the shortage of conductive scaffolds for repairing tendon defects, revealing the potential impact of conductivity on the signaling pathway of tendon repair and providing a new approach for future clinical studies.

Background: Extensor tendon injuries require surgical repair, followed by rehabilitation to ensure optimal outcomes. Immobilization has been the cornerstone of postoperative management. However, immobilization after surgery frequently makes the finger stiffness, often resulting in reduced functionality and quality of life for patients. Recent studies indicate that early controlled motion can significantly improve outcomes, but safe early range of motion (ROM) exercise is a significant clinical challenge. This article aims to check the efficacy of the novel designed finger ROM brace for preventing finger stiffness for extensor tendon injuries with case series., Methods: A finger ROM brace was designed based on the natural finger movement. Like a real finger, there are two tiny hinge joints and three round-shape body components. The design aimed to be ergonomic dynamic splint assisting controlled motion to promote early motion, thus reducing tendon tension and preventing stiffness. Elastic resistant ROM exercise could be by inserting a silicone band into the groove on the components and free movement could be achieved by removing a silicone band., Result: Between December 2022 and July 2023, 10 patients who underwent tenorrhaphy because of extensor tendon laceration were involved. Complete extensor tendon laceration was 3 patients, other seven patients had partial laceration of extensor tendons. Surgery was performed within 2 days of injury, and no infection was observed in all patients. After the extensor tendon was confirmed as healed state by ultrasound, the patients were permit the active exercise wearing finger ROM brace with a silicone band. Within 1-2 weeks after elastic resistant exercise, the patients could achieve free full ROM movement without any complication., Conclusion: The novel finger ROM brace combines the advantages of dynamic splinting and under-actuated mechanisms to offer a comprehensive solution for preventing stiffness after extensor tendon suture. Future studies should focus on clinical trials to validate the efficacy and safety of this brace in a larger population., (© 2024. The Author(s).)

Background: Percutaneous and minimally invasive suturing techniques are very important in the treatment of acute Achilles tendon ruptures because they combine the advantages of surgical treatment (low re-rupture rate) and non-opervative treatment (low risk of complications). In the authors' approach, the percutaneous, peritendineum-preserving technique with the Dresden instrument has proven itself as a standard treatment for 20 years., Dresden Technique: Strict adherence to the original Dresden technique with posteromedial incision and subfascial preparation is crucial for the safe avoidance of the sural lesions regularly reported in percutaneous procedures. The rupture zone and the peritendineum should not be opened. By adding a third suture and using non-absorbable suture material, stability comparable to the open Krackow suture technique is achieved. Functional aftertreatment with protection in a special boot and appropriate supervision of the patient aims at early rehabilitation while minimizing the risk of re-rupture or loss of tension., Outlook: The focus of future efforts should be to further improve treatment results through individualized postoperative treatment adapted to tendon healing., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: The Achilles tendon is the strongest tendon in humans and is frequently injured, especially in the physically active young to middle-aged population. An increasing frequency of Achilles tendon ruptures (ATR) has been reported in several studies. However, there is no international consensus regarding possible non-operative (N-OP) or operative (surgical) treatment (OP)., Objectives: The aim of this article is to semi-quantitatively compare both treatment options for ATR by analyzing the results reported in the literature., Material and Methods: For this purpose, relevant categories were identified, and the literature was then evaluated in a PubMed analysis. Ten meta-analyses and two cost analyses were included. The data was extracted according to the categories and evaluated comparatively., Results: OP and N‑OP for acute ATR can lead to equally good restitution of clinical function if early functional rehabilitation is applied. The lower re-rupture rate is an advantage of OP, whereas the lower general complications speak in favor of N‑OP. The minimally invasive or percutaneous surgical technique (M-OP) appears to be advantageous over the open surgical technique (O-OP), although studies show an increased rate of lesions of the sural nerve., Conclusion: There is no consensus regarding the superiority of OP or N‑OP for acute ATR, as several studies conducted since the introduction of early mobilization protocols have shown similar results for these two interventions. Results and complications of M‑OP and O‑OP are also comparable. Considering the available data on the various surgical procedures, the authors prefer the M‑OP technique with adequate sural nerve protection for repair of acute ATR, combined with an early mobilization protocol., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Mesenchymal stromal cells (MSCs) have immense potential for use in musculoskeletal tissue regeneration; however, there is still a paucity of evidence on the effect of tenogenic MSCs (TMSCs) in tendon healing in vivo . This study aimed to determine the effects of growth differentiation factor 5 (GDF5)-induced rabbit MSCs (rbMSCs) on infraspinatus tendon healing in a New Zealand white rabbit model. In this study, bone marrow-derived rbMSCs were isolated, and 100 ng/mL GDF5 was used to induce tenogenic differentiation in rbMSC. The effects of GDF5 on rbMSC in vitro were assessed by total collagen assay, gene expression analysis, and immunofluorescence staining of tenogenic markers; native tenocytes isolated from rabbit tendon were used as a positive control. In in vivo , a window defect was created on the infraspinatus tendons bilaterally. After 3 weeks, the rabbits ( n = 18) were randomly divided into six groups and repaired with various interventions: (1) surgical suture; (2) fibrin glue (FG); (3) suture and FG; (4) suture, FG, and rabbit tenocytes (rbTenocyte); (5) suture, FG, and rbMSCs, and (6) suture, FG, and TMSC. All animals were euthanized at 6 weeks postoperatively. The in vitro GDF5-induced rbMSCs (or TMSC) showed increased total collagen expression, augmented scleraxis ( SCX ), and type-I collagen ( COL1A1 ) mRNA gene expression levels. Immunofluorescence showed similar expression in GDF5-induced rbMSC to that of rbTenocyte. In vivo histological analysis showed progressive tendon healing in the TMSC-treated group; cells with elongated nuclei aligned parallel to the collagen fibers, and the collagen fibers were in a more organized orientation, along with macroscopic evidence of tendon callus formation. Significant differences were observed in the cell-treated groups compared with the non-cell-treated groups. Histological scoring showed a significantly enhanced tendon healing in the TMSC- and rbMSC-treated groups compared with the rbTenocyte group. The SCX mRNA expression levels, at 6 weeks following repair, were significantly upregulated in the TMSC group. Immunofluorescence showed COL-1 bundles aligned in parallel orientation; this was further confirmed in atomic force microscopy imaging. SCX, TNC, and TNMD were detected in the TMSC group. In conclusion, GDF5 induces tenogenic differentiation in rbMSCs, and TMSC enhances tendon healing in vivo compared with conventional suture repair. Impact Statement Tendon tears and degeneration are debilitating clinical conditions. To date, the suture method is the only gold standard for repairing tendons. Mesenchymal stromal cells (MSCs) have been suggested for many years for their potential in tissue regeneration, especially in tendon-degenerative conditions. Growth differentiation factor 5 (GDF5) has been reported to induce human MSC into a tenogenic lineage (or TMSC), hence a potential cell source for tendon regeneration. This study reported on the potential of rabbit MSC to differentiate into TMSC via GDF5 induction and the potential of TMSC in tendon healing in a New Zealand white rabbit infraspinatus tendon model fulfilled with the 3R principle (reduce, reuse, and replace).

Background: Due to the spatiotemporal complexity of the composition, structure, and cell population of the tendon-bone interface (TBI), it is difficult to achieve true healing. Recent research is increasingly focusing on engineered exosomes, which are a promising strategy for TBI regeneration., Aim of Review: This review discusses the physiological and pathological characteristics of TBI and the application and limitations of natural exosomes in the field of tendon-bone healing. The definition, loading strategies, and spatiotemporal properties of engineered exosomes were elaborated. We also summarize the application and future research directions of engineered exosomes in the field of tendon-bone healing., Key Scientific Concepts of Review: Engineered exosomes can spatially deliver cargo to targeted sites and temporally realize the sustained release of therapeutic molecules in TBI. This review expounds on the multidifferentiation of engineered exosomes for tendon-bone healing, which effectively improves the biological and biomechanical properties of TBI. Engineered exosomes could be a promising strategy for tendon-bone healing., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Production and hosting by Elsevier B.V.)

Tendon injuries are pervasive orthopedic injuries encountered by the general population. Nonetheless, recovery after severe injuries, such as Achilles tendon injury, is limited. Consequently, there is a pressing need to devise interventions, including biomaterials, that foster tendon healing. Regrettably, tissue engineering treatments have faced obstacles in crafting appropriate tissue scaffolds and efficacious nanomedical approaches. To surmount these hurdles, an innovative injectable hydrogel (CP@SiO 2 ), comprising puerarin and chitosan through in situ self-assembly, is pioneered while concurrently delivering mesoporous silica nanoparticles for tendon healing. In this research, CP@SiO 2 hydrogel is employed for the treatment of Achilles tendon injuries, conducting extensive in vivo and in vitro experiments to evaluate its efficacy. This reults demonstrates that CP@SiO 2 hydrogel enhances the proliferation and differentiation of tendon-derived stem cells, and mitigates inflammation through the modulation of macrophage polarization. Furthermore, using histological and behavioral analyses, it is found that CP@SiO 2 hydrogel can improve the histological and biomechanical properties of injured tendons. This findings indicate that this multifaceted injectable CP@SiO 2 hydrogel constitutes a suitable bioactive material for tendon repair and presents a promising new strategy for the clinical management of tendon injuries., (© 2024 Wiley‐VCH GmbH.)

Orthopaedic and sports medicine clinicians can improve outcomes for transgender patients by understanding the physiological effects of gender-affirming hormone therapy (GAHT). This narrative review investigated the role of GAHT on bone mineral density, fracture risk, thromboembolic risk, cardiovascular health and ligament/tendon injury in this population. A search from the PubMed database using relevant terms was performed. Studies were included if they were levels 1-3 evidence. Due to the paucity of studies on ligament and tendon injury risk in transgender patients, levels 1-3 evidence on the effects of sex hormones in cisgender patients as well as basic science studies were included for these two topics. This review found that transgender patients on GAHT have an elevated fracture risk, but GAHT has beneficial effects on bone mineral density in transgender women. Transgender women on GAHT also have an increased risk of venous thromboembolism, stroke and myocardial infarction compared with cisgender women. Despite these elevated risks, studies have found it is safe to continue GAHT perioperatively for both transgender women and men undergoing low-risk operations. Orthopaedic and sports medicine clinicians should understand these unique health considerations for equitable patient care., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

The aim of this study was to evaluate the effect of adipose-derived stem cells (ADSCs) in the treatment of acute rupture of the Achilles tendon. It was a cross-sectional study involving 15 patients. Patients were randomly divided: group 1-rupture; group 2-suture; group 3-rupture + ADSCs. In the AOFAS score, the score was higher in group 3 with a significant difference. In the ATRS score, the score was higher in groups 2 and 3, also with a significant difference. As for the ultrasound score, there was a significant difference between the experimental groups in relation to this score, however, in the multiple comparisons test, comparing two groups at a time, it was possible to observe a significant difference of the experimental groups. It can be concluded that cell therapy in this condition may be a treatment option due to tissue regeneration and significant recovery of function., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: Surgical outcomes for proximal hamstring avulsion injury (PHAI) are well documented, yet comparative analyses with nonsurgical approaches remain scarce., Purpose: To compare the functional outcomes between surgical and nonsurgical interventions for PHAI., Study Design: Cohort study; Level of evidence, 3., Methods: This comparative study, conducted at a sports surgery center between January 2012 and July 2021, focused on patients with primary PHAI. The study was a retrospective analysis of prospectively collected data. Group selection involved utilizing propensity score matching to compare an arm of patients who were surgically treated (indications included patients with complete injury, patients with partial injury with >2 cm of retraction, and patients for whom 6 months of nonsurgical treatment failed) with another arm of patients who refused surgery. The primary outcome was evaluated using the Parisian Hamstring Avulsion Score (PHAS). The secondary outcomes included the Tegner Activity Scale (TAS) score; University of California, Los Angeles (UCLA) score; rate and quality of return to sport (RTS); and patient satisfaction., Results: The study included 32 patients (mean age, 55.8 years [SD, 8.4 years]) in the nonsurgical treatment arm and 95 patients in the surgical treatment arm (mean age, 53.4 years [SD, 7.7 years]) ( P > .05). The interval from injury to treatment was 5.7 months (SD, 9.6 months) for the surgical group and 12.7 months (SD, 25.9 months) for the nonsurgical group ( P > .05). At the final follow-up (nonsurgical group: mean, 56.5 months [SD, 28.2 months]; surgical group: mean, 50.7 months [SD, 33.1 months]), the PHAS was significantly higher in the surgical group (mean, 86.3 [SD, 13.7]) compared with the nonsurgical group (mean, 69.8 [SD, 15.1]) ( P < .0001). Higher activity scores were also observed in the surgical group for the TAS and UCLA scores ( P = .0224 and P = .0026, respectively). A higher percentage of the surgical group (68.4%) returned to sports compared with the nonsurgical group (46.9%) ( P = .0354), with a greater proportion in the surgical group returning at the same or higher level (67.7% vs 26.7%) ( P = .0069). Additionally, a higher satisfaction level was reported by patients in the surgical group (89.5%) in contrast to the nonsurgical group (25%) ( P < .0001). Three patients in the surgical group experienced complications (2 reruptures and 1 hyperesthesia at the pudendal nerve territories). Odds ratios (ORs) indicated that patients in the surgical group were significantly more likely to achieve or exceed median scores for the PHAS (OR, 6.79; P < .001), TAS score (OR, 2.29; P = .045), and UCLA score (OR, 3.63; P = .003), as well as to RTS at any level (OR, 2.46; P = .031) or at the preinjury level or higher (OR, 6.04; P < .001)., Conclusion: This study demonstrated that surgical treatment of PHAI significantly enhances long-term functional scores, including the PHAS, TAS score, UCLA score, satisfaction, and RTS, at a mean follow-up of >4 years compared with nonsurgical treatment., Registration: NCT02906865 (ClinicalTrials.gov identifier)., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: N.L. is a consultant for WebSurvey Society, Paris, France. A.H. is a consultant for Arthrex and DePuy. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Treatment outcomes for Achilles tendon ruptures depend upon prompt diagnosis and management. A local study in 2018 highlighted inefficiencies in patient management, and a revised protocol was introduced allowing investigation and referral to be initiated by other healthcare professionals. This retrospective audit evaluates the impact of this on the timescale from presentation to treatment. It analyzes all suspected Achilles tendon ruptures within one District General Hospital from April 2021 to March 2022. Data regarding patient timelines was compared to the 2018 study. Over 12 months, 99 patients were referred to Virtual Fracture Clinic, 87.8% (n = 87) of which had a complete or partial tear on ultrasound scan (USS). In comparison to 2018, the average time from presentation to USS request reduced from 2.9 to 1.1 days (p < .01). 95% were scanned within one week of USS request and 31.3% within 48 hours (81% and 18%, previously). The average time from USS request to scan went from 6.8 to 3.2 days (p < .01). The time from presentation to treatment decision reduced from 10.9 to 6.2 days (p < .01) and the percentage of patients with a definitive treatment plan within one week increased from 34.5% to 74.2% (p < .01). Patients required 0.8 fewer appointments (p < .01) giving an estimated total saving of $10,110 ($128 per patient) during the analyzed period. The Achilles Tendon Rupture Pathway has significantly improved the proportion of patients undergoing USS within 48 hours and receiving a treatment decision within one week. This study demonstrates an efficient, cost-saving and replicable pathway for Achilles tendon ruptures., (Crown Copyright © 2024. Published by Elsevier Inc. All rights reserved.)

Background: Mesenchymal stem cells are an innovative therapeutic for various equine orthopaedic diseases, including soft tissue injuries., Objectives: To evaluate the safety and efficacy of tenogenic primed equine allogeneic peripheral blood-derived mesenchymal stem cells (tpMSCs) in horses with naturally occurring superficial digital flexor tendon (SDFT) and suspensory ligament (SL) injuries., Study Design: Multicentre, blinded, randomised, placebo-controlled clinical trial., Methods: One hundred client-owned horses with SDFT and SL injuries were randomised to receive an intralesional tpMSC (66) or saline (34) injection. Clinical and ultrasonographic evaluation was performed before treatment and on Days 56 ± 3 and 112 ± 3 after treatment. Long-term data on re-injury was collected up to 2 years after treatment., Results: Significantly more tpMSC-treated horses achieved improvement in fibre alignment score (FAS) (100% vs. 54.5%, p < 0.001) and echogenicity (97.0% vs. 57.6%, p < 0.001) on Day 112 ± 3, and their lesion size decreased significantly (-27.6 ± 25.91 vs. -4.6 ± 26.64 mm 2 , p < 0.001) compared to the placebo group. A FAS = 0 was achieved in 65% of tpMSC-treated horses, as compared to 9% of placebo-treated horses at Day 112 ± 3. The attending veterinarians reported no re-injury in 41 of 53 tpMSC and in 2 of 26 saline-treated horses available for long-term follow-up (p < 0.001)., Main Limitations: As this study consisted of client-owned horses, no samples for histology were collected. Long-term follow-up was only available for a subset of enrolled horses., Conclusions: The intralesional administration of tpMSCs was safe and improved the quality of healing and long-term outcomes in sports horses with naturally occurring SDFT and suspensory injuries., (© 2023 Boehringer Ingelheim Vetmedica. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Tendons are fibroblastic structures that link muscle and bone. There are two kinds of tendon injuries, including acute and chronic. Each form of injury or deterioration can result in significant pain and loss of tendon function. The recovery of tendon damage is a complex and time-consuming recovery process. Depending on the anatomical location of the tendon tissue, the clinical outcomes are not the same. The healing of the wound process is divided into three stages that overlap: inflammation, proliferation, and tissue remodeling. Furthermore, the curing tendon has a high re-tear rate. Faced with the challenges, tendon injury management is still a clinical issue that must be resolved as soon as possible. Several newer directions and breakthroughs in tendon recovery have emerged in recent years. This article describes tendon injury and summarizes recent advances in tendon recovery, along with stem cell therapy, gene therapy, Platelet-rich plasma remedy, growth factors, drug treatment, and tissue engineering. Despite the recent fast-growing research in tendon recovery treatment, still, none of them translated to the clinical setting. This review provides a detailed overview of tendon injuries and potential preclinical approaches for treating tendon injuries.

Background: There is no consensus on the frequency and timing of platelet-rich plasma (PRP) injection in tendon healing. We aimed to evaluate the effectiveness of single versus multiple PRP injections in the healing of patellar tendon defects in the experimental model, through histological and biomechanical investigation., Methods: Forty-four male skeletally mature Dutch rabbits were randomly divided into the five study groups ( A, B,C, D,E). After creating a longitudinal acute patellar tendon defect on both knees (One-third the width of the patella tendon), the right legs of the rabbits were used as the intervention group and the left legs as the control groups. Animals in groups A, B, and C were euthanized on days 7, 14, and 28, respectively, after the first PRP injection. Animals in group D received the second PRP injection on day 10 and was euthanized on day 14. Animals in group D received the second and third PRP injections on days 10 and 20, respectively, and were euthanized on day 28. The outcomes were evaluated histologically (modification of Movin's Grading) and biomechanically., Results: The inflammatory condition was exaggerated in groups D and E. Load at failure was higher in the non-injected side of groups D and E, while there was no significant difference between the right and left legs of the three groups A, B and C. In other word, groups with a single PRP injection were more resistant to the increasing load compared to the groups with multiple PRP injections., Conclusions: PRP improves tendon healing if injected early after injury, while its injection after the initial phase of injury hampers tendon healing. In addition, a single PRP injection seems to be more effective than multiple PRP injection. Therefore, in cases where PRP injection is indicated for tendon repair, such as acute tendon injury, we recommend using a single PRP injection during tendon repair surgery., (© 2024. The Author(s).)

Recent research shows that the functional outcome after an acute Achilles tendon rupture is comparable after conservative versus operative treatment. It is therefore recommended to treat patients conservatively, but strong reasons for surgical treatment exist. In principle, no additional radiographic diagnostic exams are indicated for the diagnosis. An appropriate anamnesis, palpable gap and positive Thompson test have an excellent sensitivity. In case of doubt, an ultrasound should be performed as the first step. A shared decision process should be pursued for establishing treatment plan. However, it is recommended that patients be treated conservatively unless strong arguments for surgical intervention are present. It is important to properly inform patients, and thus manage expectations about the expected rehabilitation process. If there is an increased risk of re-rupture, such as in athletes or during physically demanding work, surgical treatment can be considered. Then a surgical technique in which expertise and experience has been gained should be used as no difference in outcome have been found after open versus minimal invasive techniques.

Tendons, complex fibrous structures, are subjected to great tensions, which can give rise to the so-called tendinopathies. This study aimed to evaluate photobiomodulation and human Amniotic Membrane applied as single or combined therapies to treat induced Achilles tendon lesions. Seventy-five rats were divided into five groups (n=15): C- control Sham surgery; I- tendon injury; LA- tendon injury treated with photobiomodulation; AM- tendon injury treated with Amniotic Membrane; LAM- tendon injury + photobiomodulation and Amniotic Membrane, subdivided into three groups (n=5) with analysis at 3, 7, and 14 days. The tendon injuries were made with a 20 g weight released from a mini guillotine onto the ankle in dorsiflexion. AM and LAM groups received an Amniotic Membrane fragment while LA and LAM groups received transcutaneous photobiomodulation, using a 660 nm wavelength laser. The inflammatory cells showed statistical differences between groups C and I (p<0.05), I and AM (p<0.01), I and LA (p<0.05), and I and LAM (p<0.01). Both photobiomodulation and Amniotic Membrane were shown to enhance tendon repair, and the association of photobiomodulation plus Amniotic Membrane was the most effective treatment. We conclude that the association of photobiomodulation plus Amniotic Membrane was effective in accelerating and improving the tendon regeneration process.

Background: Operative treatment is widely used for acute proximal hamstring avulsions, but its effectiveness compared with that of nonoperative treatment has not been shown in randomized trials., Methods: In this noninferiority trial at 10 centers in Sweden and Norway, we enrolled patients 30 to 70 years of age with a proximal hamstring avulsion in a randomized trial and a parallel observational cohort. Treatments were operative reinsertion of the tendons or nonoperative management. The primary end point was the Perth Hamstring Assessment Tool (PHAT) at 2 years of follow-up. Secondary outcomes included scores on the Lower Extremity Functional Scale (LEFS)., Results: A total of 119 patients were enrolled in the randomized trial and 97 patients in the observational cohort. In the per-protocol analysis of the randomized trial, the mean (±standard deviation) PHAT scores were 79.9±19.5 and 78.5±19.4 in the operative and nonoperative groups, respectively (PHAT scores range from 0 to 100, with higher scores indicating higher function). The prespecified noninferiority limit of 10 points was not crossed (mean difference, -1.2; 95% confidence interval [CI], -8.6 to 6.2; P=0.009 for noninferiority). Analyses of secondary outcomes, including a mean difference in the LEFS score of -1.6 (95% CI, -5.2 to 2.0), aligned with the primary outcome. The observed numbers of adverse events in the randomized trial were nine in the operative group versus three in the nonoperative group (odds ratio, 0.3; 95% CI, 0.1 to 1.2). In the analysis of the observational cohort, the mean PHAT score difference between the nonoperative and operative treatment groups was -2.6 (95% CI, -9.9 to 4.6)., Conclusions: In patients 30 to 70 years of age with proximal hamstring avulsions, nonoperative treatment was noninferior to operative treatment. (Funded by Afa Försäkring and others; ClinicalTrials.gov number, NCT03311997.).

With up to 50 incidents per 100,000 inhabitants, Achilles tendon ruptures are among the most frequent tendon injuries encountered in orthopedics and trauma surgery. Apart from high-risk forms of sport, degenerative processes are primarily responsible for weakening and ultimately rupture. In addition to assessing the typical clinical signs with inability to perform powerful plantar flexion, the diagnostics include easy to earn examination techniques, such as the Thompson test and ultrasound as the imaging gold standard. Conservative and surgical treatment are available depending on the constitution, age and requirements of the patient. The latter option is divided into conventional open, minimally invasive or percutaneous procedures. Good to very good results can be expected regardless of the form of treatment, provided that early functional rehabilitation is carried out. The average rerupture rate is 5% and the return to sport rate is around 80%., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Purpose: In this study, we aimed to investigate the effects of hyperbaric oxygen therapy and enoxaparin sodium, which are known to accelerate bone tissue healing as well as tendon and soft tissue healing, on the healing of Achilles tendon rupture., Methods: Thirty-six rats were used in the present study. All rats were divided into groups of nine. The groups were the enoxaparin sodium group, enoxaparin sodium and hyperbaric oxygen group, hyperbaric oxygen group and control group. After 21 days, the process was completed, and the rats were sacrificed. Achilles tendon samples were evaluated histopathologically., Results: The groups were compared according to the results of statistical analysis based on the histopathological data. There was no significant difference between the groups in terms of acute inflammation (p = 0.785) or chronic inflammation (p = 0.827) scores, but there were significant differences in neovascularization (p = 0.009), proliferation (p < 0.001) and fibrosis (p = 0.006) scores., Conclusion: Our study showed that the use of enoxaparin sodium and hyperbaric oxygen had a positive effect on the healing of the Achilles tendon. Based on these results, we believe that the use of enoxaparin sodium and hyperbaric oxygen therapy after Achilles tendon rupture will be beneficial for healing and preventing complications., (© 2024. The Author(s).)

The long head of the biceps (LHB) tendon is a common source of shoulder pain. Often associated with other injuries, the tendon can alone be responsible of the symptoms. Spontaneous rupture has been observed to allow for pain relief. The spectrum of LHB lesions is broad. Repetitive motion, carrying heavy loads, have been associated with diagnosis. Specific tests have been described to diagnose biceps injuries, their implementation can remain difficult in the presence of associated pathologies. The combination of a history and clinical examination with the use of targeted imaging is required to establish the diagnosis. The management of bicipital pathologies is frequently carried out following main surgical procedures. Isolated management of biceps lesions can provide a satisfactory result when a comprehensive procedure cannot be performed., Competing Interests: Les auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Background and Purpose: The aim of our study was to assess the regional variations in Achilles tendon rupture incidence and treatment methods in Finland during the period 1997-2019., Methods: The Finnish National Hospital Discharge Register (NHDR) and the Finnish Register of Primary Health Care Visits (PHCR) were searched to identify all adult patients diagnosed with Achilles tendon rupture during our study period. The population-based annual incidence and incidences of surgically and non-surgically treated Achilles tendon ruptures were calculated for each hospital district., Results: Achilles tendon rupture incidence increased from 17.3 per 105 person-years in 1997 to 32.3 per 105 in 2019. The mean incidence of Achilles tendon ruptures ranged from 26.4 per 105 (North Savo) to 37.2 per 105 (Central Ostrobothnia). The incidence of Achilles tendon ruptures increased in all areas. The proportion of non-surgical treatment of Achilles tendon ruptures ranged in 1997 from 7% (Vaasa) to 67% (Åland) and in 2019 from 73% (Southwest Finland) to 100% (East Savo, Kainuu, Länsi-Pohja, Åland). During the study period, a shift towards non-surgical treatment was evident in all hospital districts., Conclusion: Regional variations in Achilles tendon rupture incidence exist in Finland; however, the incidence increased in all areas during the follow-up period. More Achilles tendon rupture patients are currently being treated non-surgically throughout the country.

Tendon injuries are common orthopedic ailments with a challenging healing trajectory, especially in cases like the Achilles tendon afflictions. The healing trajectory of tendon injuries is often suboptimal, leading to scar formation and functional impairment due to the inherent low metabolic activity and vascularization of tendon tissue. As pressing is needed for effective interventions, efforts are made to explore biomaterials to augment tendon healing. However, tissue engineering approaches face hurdles in optimizing tissue scaffolds and nanomedical strategies. To navigate these challenges, an injectable hydrogel amalgamated with human umbilical vein endothelial cells-derived exosomes (HUVECs-Exos) was prepared and named H-Exos-gel in this study, aiming to enhance tendon repair. In our research involving a model of Achilles tendon injuries in 60 rats, we investigated the efficacy of H-Exos-gel through histological assessments performed at 2 and 4 weeks and behavioral assessments conducted at the 4-week mark revealed its ability to enhance the Achilles tendon's mechanical strength, regulate inflammation and facilitate tendon regeneration and functional recovery. Mechanically, the H-Exos-gel modulated the cellular behaviors of macrophages and tendon-derived stem cells (TDSCs) by inhibiting inflammation-related pathways and promoting proliferation-related pathways. Our findings delineate that the H-Exos-gel epitomizes a viable bioactive medium for tendon healing, heralding a promising avenue for the clinical amelioration of tendon injuries., (© 2024. The Author(s).)

There are many high-level studies comparing nonoperative treatment, open repair, and minimally invasive repair for Achilles tendon ruptures. This article summarizes the most up-to-date literature comparing these treatment options. The authors' preferred protocol for nonoperative treatment is discussed. Preferred techniques for open repair and chronic Achilles repair are discussed with reference to the literature., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Pulley injuries are common among rock climbers, which is a growing population. Hand therapists need a therapeutic intervention which promotes healing and enables participation., Purpose: The purpose of this case series is to detail the functional outcomes of a 12-week protocol using a pulley ring orthosis (PRO) among rock climbers with a grade I, II, or III pulley injury., Study Design: A prospective repeated measures case series followed the healing timeline of four participants who rock climbed while wearing the invervention device, the PRO, with weekly measurements to monitor healing METHODS: Participants with a grade I, II, or III A2 pulley injury were custom fitted for a PRO, which they wore while rock climbing a minimum of 3 times per week for 12 weeks. Weekly check-ins were scheduled for subjective and objective measurements., Results: All participants demonstrated indicators of full healing, which, in this study, is defined as progressive improvement in strength, function, and pain, without interruption of their typical rock climbing schedules., Conclusions: Providers should consider the use of a PRO as a protective orthosis for rock climbing patients with a low-grade A2 pulley injury who want to continue rock climbing while they are healing., Competing Interests: Declaration of competing interest The corresponding author, E.H., currently fabricates the PRO in her private clinic, Hand And Rock-climbing Therapeutic Network LLC, and bills the PRO as the L Code FO L3925., (Copyright © 2024 Elsevier Inc. All rights reserved.)

A major problem after tendon injury is adhesion formation to the surrounding tissue leading to a limited range of motion. A viable strategy to reduce adhesion extent is the use of physical barriers that limit the contact between the tendon and the adjacent tissue. The purpose of this study was to fabricate an electrospun bilayered tube of hyaluronic acid/polyethylene oxide (HA/PEO) and biodegradable DegraPol® (DP) to improve the anti-adhesive effect of the implant in a rabbit Achilles tendon full laceration model compared to a pure DP tube. Additionally, the attachment of rabbit tenocytes on pure DP and HA/PEO containing scaffolds was tested and Scanning Electron Microscopy, Fourier-transform Infrared Spectroscopy, Differential Scanning Calorimetry, Water Contact Angle measurements, and testing of mechanical properties were used to characterize the scaffolds. In vivo assessment after three weeks showed that the implant containing a second HA/PEO layer significantly reduced adhesion extent reaching levels comparable to native tendons, compared with a pure DP implant that reduced adhesion formation only by 20 %. Tenocytes were able to attach to and migrate into every scaffold, but cell number was reduced over two weeks. Implants containing HA/PEO showed better mechanical properties than pure DP tubes and with the ability to entirely reduce adhesion extent makes this implant a promising candidate for clinical application in tendon repair., Competing Interests: Declaration of competing interest The authors declare that they do not have any competing interests., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: To investigate early structural and mechanical predictors of plantarflexor muscle strength and the magnitude of Achilles tendon (AT) nonuniform displacement at 6 and 12 months after AT rupture., Methods: Thirty-five participants (28 males and 7 females; mean ± SD age 41.7 ± 11.1 years) were assessed for isometric plantarflexion maximal voluntary contraction (MVC) and AT nonuniformity at 6 and 12 months after rupture. Structural and mechanical AT and plantarflexor muscle properties were measured at 2 months. Limb asymmetry index (LSI) was calculated for all variables. Multiple linear regression was used with the 6 and 12 month MVC LSI and 12 month AT nonuniformity LSI as dependent variables and AT and plantarflexor muscle properties at 2 months as independent variables. The level of pre- and post-injury sports participation was inquired using Tegner score at 2 and 12 months (scale 0-10, 10 = best possible score). Subjective perception of recovery was assessed with Achilles tendon total rupture score (ATRS) at 12 months (scale 0-100, 100=best possible score)., Results: Achilles tendon resting angle (ATRA) symmetry at 2 months predicted MVC symmetry at 6 and 12 months after rupture (β = 2.530, 95% CI 1.041-4.018, adjusted R 2  = 0.416, p = 0.002; β = 1.659, 95% CI 0.330-2.988, adjusted R 2  = 0.418, p = 0.016, respectively). At 12 months, participants had recovered their pre-injury level of sports participation (Tegner 6 ± 2 points). The median (IQR) ATRS score was 92 (7) points at 12 months., Conclusion: Greater asymmetry of ATRA in the early recovery phase may be a predictor of plantarflexor muscle strength deficits up to 1 year after rupture., Trial Registration: This research is a part of "nonoperative treatment of Achilles tendon rupture in Central Finland: a prospective cohort study" that has been registered in ClinicalTrials.gov (NCT03704532)., (© 2024 The Author(s). Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Background: Achilles tendon is vital in maintaining the stability and function of ankle joint. It is quite difficult to achieve the structural and functional repair of Achilles tendon in tissue engineering., Methods: A tissue-engineered tendon micro-tissue was prepared using rat tail tendon extracellular matrix (TECM) combined with rat adipose stem cells (ADSCs) to repair Achilles tendon injuries. The TECM was prepared by repeated freezing and thawing. The in vitro characteristics of TECM and its effect on ADSCs proliferation were detected. This tissue-engineered tendon micro-tissue for Achilles tendon repair in vivo was evaluated based on general characteristics, gait analysis, ultrasound findings, histological analysis, and biomechanical testing., Results: The results showed that the TECM scaffold had good biocompatibility for ADSCs. At 2 weeks post-surgery, collagen types I and III and tenomodulin expression were higher, and vascular endothelial growth factor expression was lower in the micro-tissue group than other groups. At 4 and 8 weeks post-surgery, the results of histological analysis and ultrasound findings showed that the repaired tendon tissue was smooth and lustrous, and was arranged regularly and evenly in the micro-tissue group. Gait analysis confirmed that better motor function recovery was noted in micro-tissue group than other groups. In addition, the mechanical properties of the repaired tendon tissue in micro-tissue group were better than other groups., Conclusion: Tissue-engineered tendon micro-tissue fabricated by TECM and ADSCs has good biocompatibility and can promote structural and functional repair of tendon in vivo. This composite biomaterial has broad application prospects in tissue engineering., (© 2024. The Author(s).)

Background: Achilles tendon rupture (ATR) account for 10.7% of all tendon and ligament injuries and causes lasting muscular deficits and have a profound impact on patients' quality of life. The incidence, characteristics and management of ATR in the United Kingdom (UK) is poorly understood. This investigation aims to understand the incidence of ATR in the UK., Methods: Prospective data collection of ATR incidence from a United Kingdom Emergency department. Retrospective review of management protocols and immobilisation duration from electronic medical records., Results: ATR incidence is 8 per 100,000 people per annum. Participants were predominately male (79.2%) and primarily reported a sporting mechanism of injury (65.2%). Mean immobilisation duration was 63.1 days. 97.1% were non-surgically managed post ATR. 46.2% of participants had experienced a previous ATR or Achilles tendinopathy prior to their current ATR., Conclusion: The incidence of ATR found was 8. cases per 100,000 people per annum. Most ATR were managed non-surgically in this cohort. The majority of ruptures occurred during sporting activity. Almost one quarter (23.3%) of individuals report Achilles pain prior to ATR., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Briggs-Price et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Abstract: A 72-year-old male presented for evaluation of a 2-wk history left buttock pain that began while playing pickleball. He sustained a left inversion ankle sprain while in a squatted position and landed on his left buttock. Four days after his injury, he developed extensive bruising involving his lower back, buttock, and left thigh. On examination, he had tenderness to palpation at the left side of the sacrum and in the region of the deep external rotators. Left hip range of motion was full in extension but limited to 90° of flexion, which reproduced left-sided buttock pain. External rotation provoked pain, but internal rotation was full and pain free. MRI of the pelvis demonstrated a grade 2 partial thickness tear of the left gluteus maximus muscle at its distal myotendinous junction with associated retraction and intramuscular hematoma. He was managed with compression with biking shorts, icing, acetaminophen, and physical therapy. He returned to pickleball approximately 4 wk after his injury, and at his 4-wk follow-up, he reported 99% improvement in his symptoms with the only remaining complaint being minimal discomfort with gluteal stretching., (Copyright © 2024 by the American College of Sports Medicine.)

The purpose of this study was to investigate whether 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) combined with n-hydroxysuccinimide (NHS) can repair tendon damage caused by peracetic acid-ethanol and gamma irradiation sterilization. The semitendinosus tendons of 15 New Zealand white rabbits were selected as experimental materials, and the tendons were sterilized in a solution containing 1% (v/w) peracetic acid and 24% (v/w) ethanol. After 15 kGy gamma irradiation sterilization, the tendons were randomly divided into three groups (n = 10). The tendons were repaired with EDCs of 0, 2.5 and 5 mM combined with 5 mM NHS for 6 h, the tendons were temporarily stored at - 80 ± °C. The arrangement and spatial structure of collagen fibers were observed by light microscopy and scanning electron microscopy, the collagen type and collagen crimp period were observed under a polarizing microscope, and the collagen fibril diameter and its distribution were measured by transmission electron microscopy, from which the collagen fibril index and mass average diameter were calculated. The resistance of collagen to enzymolysis was detected by the free hydroxyproline test, and tensile fracture and cyclic loading tests of each group of tendons were carried out, from which the elastic modulus, maximum stress, maximum strain, strain energy density and cyclic creep strain were calculated. The obtained results showed that the gap between loose collagen fibers in the 0 mM control group was wider, the parallel arrangement of tendons in the 2.5 and 5 mM groups was more uniform and regular and the fiber space decreased, the crimp period in the 5 mM group was lower than that in the 0 mM group (P < 0.05), and the concentration of hydroxyproline in the 5 mM group (711.64 ± 77.95 μg/g) was better than that in the control group (1150.57 ± 158.75 μg/g). The elastic modulus of the 5 mM group (424.73 ± 150.96 MPa) was better than that of the 0 mM group (179.09 ± 37.14 MPa). Our results show that EDC combined with NHS can repair damaged tendons after peracetic acid-ethanol and gamma radiation treatment, and 5 mM EDC has better morphological performance, anti-enzymolysis ability and biomechanical properties than 2.5 mM EDC., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Non-thermal atmospheric-pressure plasma (NTAPP) has been widely studied for clinical applications, e.g., disinfection, wound healing, cancer therapy, hemostasis, and bone regeneration. It is being revealed that the physical and chemical actions of plasma have enabled these clinical applications. Based on our previous report regarding plasma-stimulated bone regeneration, this study focused on Achilles tendon repair by NTAPP. This is the first study to reveal that exposure to NTAPP can accelerate Achilles tendon repair using a well-established Achilles tendon injury rat model. Histological evaluation using the Stoll's and histological scores showed a significant improvement at 2 and 4 weeks, with type I collagen content being substantial at the early time point of 2 weeks post-surgery. Notably, the replacement of type III collagen with type I collagen occurred more frequently in the plasma-treated groups at the early stage of repair. Tensile strength test results showed that the maximum breaking strength in the plasma-treated group at two weeks was significantly higher than that in the untreated group. Overall, our results indicate that a single event of NTAPP treatment during the surgery can contribute to an early recovery of an injured tendon., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Nakazawa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

CRISPR-Cas13 holds substantial promise for tissue repair through its RNA editing capabilities and swift catabolism. However, conventional delivery methods fall short in addressing the heightened inflammatory response orchestrated by macrophages during the acute stages of tendon injury. In this investigation, macrophage-targeting cationic polymers are systematically screened to facilitate the entry of Cas13 ribonucleic-protein complex (Cas13 RNP) into macrophages. Notably, SPP1 (OPN encoding)-producing macrophages are recognized as a profibrotic subtype that emerges during the inflammatory stage. By employing ROS-responsive release mechanisms tailored for macrophage-targeted Cas13 RNP editing systems, the overactivation of SPP1 is curbed in the face of an acute immune microenvironment. Upon encapsulating this composite membrane around the tendon injury site, the macrophage-targeted Cas13 RNP effectively curtails the emergence of injury-induced SPP1-producing macrophages in the acute phase, leading to diminished fibroblast activation and mitigated peritendinous adhesion. Consequently, this study furnishes a swift RNA editing strategy for macrophages in the inflammatory phase triggered by ROS in tendon injury, along with a pioneering macrophage-targeted carrier proficient in delivering Cas13 into macrophages efficiently., (© 2024 Wiley‐VCH GmbH.)

Return to play (RTP) and functional outcomes are critical to treatment success for acute Achilles tendon rupture (AATR). This systematic review and meta-analysis explored treatment superiority essential in optimal treatment selection concerning individual patients and their expectations regarding RTP and functional outcomes. This study was in accordance with the preferred reporting items for systematic reviews and meta-analyses guidelines. The included studies were assessed regarding the level and quality of evidence. Fixed-effects models were employed for I 2 < 25% and random-effects models for I 2 ≥ 25%. The RTP rate meta-analysis of surgical vs conservative treatment revealed no significant difference. This was similar to the subgroup analysis of open repair and conservative treatment. The RTP rate and Achilles Tendon Total Rupture Score (ATRS) meta-analysis of open repair + earlier rehabilitation (ER) vs + later rehabilitation (LR) also revealed no significant differences. The mean time to RTP meta-analysis of open repair + ER vs + LR showed that open repair + ER was significantly favored (-4.19 weeks; p = .002). The ATRS meta-analysis of conservative treatment with ER vs with LR revealed no significant difference. This meta-analysis has revealed that the RTP rates following treatment of AATR are high. Therefore, the decision for surgical vs conservative treatment or open repair + ER vs + LR for AATR should not be selected based on the expectation of RTP. However, open repair + ER can be advocated over + LR for reduced mean time to RTP., (Copyright © 2024 the American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.)

Due to their function, tendons are exposed to acute injuries. This type of damage to the musculoskeletal system represents a challenge for clinicians when natural regeneration and treatment methods do not produce the expected results. Currently, treatment is long and associated with long-term complications. In this review, we discuss the use of stem cells in the treatment of tendons, including how to induce appropriate cell differentiation based on gene therapy, growth factors, tissue engineering, proteins involved in regenerative process, drugs and three-dimensional (3D) structures. A multidirectional approach as well as the incorporation of novel components of the therapy will improve the techniques used and benefit patients with tendon injuries in the future.

Background: Platelet-rich plasma (PRP) and mesenchymal stromal or stem cells (MSCs) have been investigated as treatments for equine tendon and ligament injuries, but little consensus exists on the efficacy of these treatments. The study sought to evaluate the efficacy of PRP and MSC treatments by systematic review and meta-analysis., Methods: A systematic review was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. Inclusion criteria required an original, peer-reviewed study where horses were administered MSCs or PRP (or both), and a comparator group was described. Studies were assessed for risk of bias and study quality. Random effects meta-analysis with inverse variance weighting was used to calculate pooled estimates of the ORs for the primary outcomes of return to performance and reinjury., Results: The search criteria identified 764 unique studies, and 21 studies met the inclusion criteria for the systematic review. Seventeen studies were further assessed for the primary outcomes of return to performance and reinjury rate within a meta-analysis. Meta-analyses revealed no increase in the likelihood of a return to performance with any of the biologic treatments. However, MSCs and MSCs administered concurrently with PRP provide a reduced risk of reinjury., Clinical Relevance: The current study identified a decrease in reinjury rate in horses administered MSCs or a combination of MSCs and PRP for tendinopathy and desmopathy. However, results should be interpreted with consideration of the heterogeneity of findings, poor study quality, and high risk of bias in the majority of studies.

Background: Achilles tendon is composed of dense connective tissue and is one of the largest tendons in the body. In veterinary medicine, acute ruptures are associated with impact injury or sharp trauma. Healing of the ruptured tendon is challenging because of poor blood and nerve supply as well as the residual cell population. Platelet-rich plasma (PRP) contains numerous bioactive agents and growth factors and has been utilized to promote healing in bone, soft tissue, and tendons., Objective: The purpose of this study was to evaluate the healing effect of PRP injected into the surrounding fascia of the Achilles tendon after allograft in rabbits., Methods: Donor rabbits (n = 8) were anesthetized and 16 lateral gastrocnemius tendons were fully transected bilaterally. Transected tendons were decellularized and stored at -80°C prior to allograft. The allograft was placed on the partially transected medial gastrocnemius tendon in the left hindlimb of 16 rabbits. The allograft PRP group (n = 8) had 0.3 mL of PRP administered in the tendon and the allograft control group (n = 8) did not receive any treatment. After 8 weeks, rabbits were euthanatized and allograft tendons were transected for macroscopic, biomechanical, and histological assessment., Results: The allograft PRP group exhibited superior macroscopic assessment scores, greater tensile strength, and a histologically enhanced healing process compared to those in the allograft control group., Conclusions: Our results suggest administration of PRP on an allograft tendon has a positive effect on the healing process in a ruptured Achilles tendon., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Korean Society of Veterinary Science.)

Spontaneous tendon or ligament ruptures are quite rare and mostly associated with chronic systemic diseases such as diabetes mellitus, systemic lupus erythematosus, rheumatoid arthritis, and chronic kidney disease (CKD). In this study, we present the first documented case of a spontaneous rupture of the medial patellofemoral ligament (MPFL) in a pediatric patient. The patient was undergoing long-term peritoneal dialysis (PD) and had a history of severe secondary hyperparathyroidism. Additionally, we discussed spontaneous tendon and ligament ruptures associated with CKD or dialysis through a comprehensive literature review. This case report highlights the importance of recognizing that spontaneous tendon or ligament injuries are not exclusive to adults; children with CKD can also be affected. Several factors including poor parathyroid hormone (PTH) and metabolic acidosis control, prolonged CKD duration and presence of malnutrition play role in the pathogenesis. Early diagnosis is crucial as it allows for timely surgical intervention and leads to a favorable functional recovery., (© 2024 Wiley Periodicals LLC.)

Case: A 19-year-old female athlete experienced calf pain during sport. A complete Achilles tendon rupture was diagnosed 4 weeks after injury. Ultrasound revealed discontinuity of the Achilles tendon with 2.0 cm of diastasis, persisting in plantarflexion. Plantarflexion immobilization was initiated, and progressive dorsiflexion was used until 10 weeks from injury. At 1 year from injury, ankle magnetic resonance imaging revealed a contiguous tendon, the patient was pain-free, and had returned to high-level athletics with equivalent sport performance relative to her preoperative status., Conclusion: Certain Achilles tendon ruptures in young people may be treated nonoperatively with good clinical outcomes, even if diagnosis and immobilization are delayed and tendon diastasis persists in maximum plantarflexion., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/C289)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Purpose of the Study: The aim of this study is to describe injury patterns, characteristics, treatment modalities and functional outcomes after punching related injuries., Material and Methods: Retrospective data of cases admitted to emergency department following punch injury between January 1, 2012, and December 31, 2022. was collected. Patient's demographic data, the dominant and injured upper extremity side, punched object, a time of patient admission were recorded. Smoking habit and blood ethanol level were documented. Trauma mechanism, diagnosis (1: dermabrasions: skin, 2: lacerations: neurovascular structures or tendons and 3: osseous pathologies), treatment modalities were analyzed. Outcomes were assessed using the DASH questionnaire (Disabilities of the Arm, Shoulder, and Hand) at the last follow-up., Results: A total of 1052 patients (male=968 (92%), female=84 (8%)) with mean age 24.6 ± 7.2 included this study. Six hundred and twenty-one (59%) patients punched a solid object and 675 (64%) had osseous pathology. The most commonly fractured bone, injured tendon, injured nerve, and injured artery were 5th metacarpal, extensor digitorum communis (EDC), ulnar nerve, and ulnar artery, respectively. The majority of the patients, (73%) were smokers while 15% of the patients had high level of blood ethanol concentration on admission (82±12.3 mg/100 ml). A comparison between smokers and non-smokers did not reveal any significant differences (p=0.425) in terms of diagnosis whereas 74% of alcoholic patients admitted with lacerations which was statistically significant (p=0.023). Injuries of 321 (30.5%) patients required surgery in the operating room, while 711(67.5 %) patients received interventions in the emergency room setting. The average DASH score differed between subgroups, with significantly higher scores in patients with laceration type injuries (7.2 SD), indicating more disability (p=0.001) DISCUSSION. The study reveales a high prevalence of hand injuries among individuals aged 18 to 40, with the dominant hand being most affected, primarily due to physical violence and self-harming behaviors. Primary contributing factors to this pattern are the escalated incidents of physical violence and self-harming behaviors arising from an inability to manage anger impulses. Punching solid objects, especially during late afternoon and evening periods often associated with alcohol use, was a common cause, resulting in metacarpal fractures being the most reported injury. Multiple tendon and nerve injuries were frequent, highlighting the severity and complexity of these traumas, often necessitating surgical intervention., Conclusions: These findings highlight the several key aspects, including demographic characteristics of the patient population, common causes and types of injuries observed, and the association between alcohol use as well as the specific injury profiles. Satisfactory results can be achieved with both conservative and surgical treatment for punch injuries., Key Words: punching, fisting, boxing injuries, laceration, blood ethanol level.

Tendinopathy is a disorder of musculoskeletal system that primarily affects athletes and the elderly. Current treatment options are generally comprised of various exercise and loading programs, therapeutic modalities, and surgical interventions and are limited to pain management. This study is to understand the role of TRIM54 (tripartite motif containing 54) in tendonitis through in vitro modeling with tendon-derived stem cells (TDSCs) and in vivo using rat tendon injury model. Initially, we observed that TRIM54 overexpression in TDSCs model increased stemness and decreased apoptosis. Additionally, it rescued cells from tumor necrosis factor α-induced inflammation, migration, and tenogenic differentiation. Further, through immunoprecipitation studies, we identified that TRIM54 regulates inflammation in TDSCs by binding to and ubiquitinating YOD1. Further, overexpression of TRIM54 improved the histopathological score of tendon injury as well as the failure load, stiffness, and young modulus in vivo. These results indicated that TRIM54 played a critical role in reducing the effects of tendon injury. Consequently, these results shed light on potential therapeutic alternatives for treating tendinopathy., Competing Interests: Conflict of interest The authors declare no conflict of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Tendon and ligament injuries, prevalent requiring surgical intervention, significantly impact joint stability and function. Owing to excellent mechanical properties and biochemical stability, Nondegradable synthetic materials, including polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE), have demonstrated significant potential in the treatment of tendon and ligament injuries. These above materials offer substantial mechanical support, joint mobility, and tissue healing promotion of the shoulder, knee, and ankle joint. This review conclude the latest development and application of nondegradable materials such as artificial patches and ligaments in tendon and ligament injuries including rotator cuff tears (RCTs), anterior cruciate ligament (ACL) injuries, and Achilles tendon ruptures., (© 2023 Wiley-VCH GmbH.)

Background: Due to its limited blood supply and irregular mechanical loading, the Achilles tendon is the most frequently ruptured tendon. Despite the rising incidence of acute Achilles tendon rupture (AATR), the optimal treatment remains controversial. Missed diagnoses and delayed treatments lead to poor outcomes and limited treatment options. This study aimed to identify potential biomarkers for diagnosing and developing therapies for AATR., Methods: We employed the coupled isobaric tag for relative and absolute quantitation-liquid chromatography-electrospray ionization-tandem mass spectrometry approach to investigate protein expression in tissues from AATR patients. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to identify differentially expressed proteins (DEPs) between AATR patients and healthy individuals. A protein-protein interaction (PPI) network of DEPs was constructed using the Search Tool for the Retrieval of Interacting Genes. The screened hub genes were selectively verified by immunohistochemical staining., Results: We identified 410 DEPs between AATR patients and controls. The DEPs were significantly enriched in GO terms such as the extracellular region, extracellular region part, and defense response, as well as KEGG pathways, including complement and coagulation cascades, focal adhesion, and regulation of actin cytoskeleton. The main hub nodes in the PPI network comprised fibronectin 1 (FN1), major histocompatibility complex, class I, B (HLA-B), filamin A (FLNA), heat shock 27-kDa protein 1 (HSPB1), heat shock protein family A member 5 (HSPA5), apolipoprotein A4 (APOA4), and myosin IC (MYO1C). Although APOA4 and collagens I, II, and III were detectable in healthy tendons, immunohistochemical staining confirmed higher expression of these proteins in the acutely ruptured Achilles tendon., Conclusions: Our findings lay a foundation for further molecular studies of AATR. Inflammation and age-related degeneration may contribute to the pathogenesis of AATR. Moreover, the identified DEPs could be potential biomarkers for AATR diagnosis and treatment., (© 2023. The Author(s).)

Background: Much has been written about the diagnosis and treatment of soft tissue mallet injuries. However, there has been little regarding the characteristics of this injury affecting patients' prognosis. The purpose of this prospective study was to identify factors influencing the outcome of treatment of soft tissue mallet injuries., Methods: Patients diagnosed with soft tissue mallet injuries were enrolled prospectively in a protocol of dorsal splinting for 6 to 12 weeks, followed by weaning over 2 weeks and then evaluated at 6, 9, and ≥ 12 months., Results: Thirty-seven patients (38 digits) completed the study. Treatment success was defined as a final extensor lag of <15° and failure as a final extensor lag of ≥ 15°. Those failing splint treatment were older compared with those successfully treated. Patient compliance was significantly associated with a successful outcome. Factors that did not significantly affect success included time to treatment, initial injury severity, splinting duration, sex, and ligamentous laxity. Disabilities of Arm, Shoulder, and Hand scores >0 were not associated with treatment failure. Radiographic and clinical extension lag were statistically comparable., Conclusions: This study shows strong association between the success of splint treatment, younger patient age, and compliance with the treatment protocol. Despite this finding, most patients did not report any functional limitations, irrespective of the treatment success. In contrast to prior results, time to treatment and initial extensor lag did not significantly affect treatment success., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Tendon injuries, commonly associated with sports activities, pose significant challenges in terms of treatment and recovery due to limited tendon regeneration and the formation of proliferative scars. Stem cell-based therapy has shown promising application, but there are still challenges. Physical and biological cues are instrumental in guiding stem cell differentiation and maturation. This study focuses on exploring the effects of matrix biomechanics on tendon stem/progenitor cells (TSPCs) differentiation. We fabricated polydimethylsiloxane (PDMS) substrates with different elastic modulus to mimic the mechanical characteristics of healthy tendons. A tissue-engineered culture system was developed for tenogenesis, and pre-differentiated tissue-engineered tendons were transplanted in vivo to assess their efficacy in regenerating patella tendon injuries. Furthermore, we demonstrated that the biomechanical stimuli activated the integrin-αm to enhance the tenogenesis capacity of TSPCs. Our findings highlight the importance of biomechanics in tendon tissue engineering and provide a novel perspective for enhancing tendon regeneration., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interests that may have impacted the research presented in this manuscript., (Copyright © 2023. Published by Elsevier Inc.)