Achilles Tendon Injury Research Articles

The Effects of Fibroblast Growth Factor-2 (FGF-2) on Achilles Tendon Injury

Category: Basic Sciences/Biologics; Ankle Introduction/Purpose: Achilles tendon defects are a challenging problem, and there is a need for new treatments. We investigated the use of Platelet-rich fibrin (PRF), a dense fibrin scaffold containing many growth factors and cytokines, for Achilles tendon injuries. The study found that PRF accelerates healing by promoting the proliferation and activation of tenocytes via FGF receptor/AKT signaling and TGF-β/SMAD3 signaling. While FGF-2, a growth factor in PRF, has been shown to promote tenocyte differentiation and proliferation, its effect on Achilles tendon injuries has not been reported. Therefore, this study aimed to investigate the effect of FGF-2 on Achilles tendon healing when administered alone and to determine its specific contribution to the healing process. Methods: We used a rat model of Achilles tendon defect. A 4-mm portion of the right Achilles tendon, 4 mm proximal to the calcaneal insertion, was resected to create a tendon defect. Gelatin hydrogel sheet (MedGel PI5) as a scaffold for PBS, FGF-2 (Rigroth®), and FGF receptor inhibitor (FGFRI: Pemigatinib) was placed into the gap before suturing it with nylon sutures. We observed HE-stained specimens at 200x and assessed histological healing by counting cells and vessels and grading cell morphology. The motor function was evaluated by the Basso, Beattie, and Bresnahan (BBB) score and the treadmill test. We compared the effects of FGF-2 on tenocytes isolated from rat Achilles tendons in the control, FGF2, and FGFRI groups. The proliferation and migration of tenocytes were measured by MTS assay and wound closure assay, respectively. Protein expression, such as Tenomodulin (Tnmd), Collagen Ⅰ, Ⅲ, and Screlaxis-A in cells, were evaluated by Western Blotting. Results: In the rat model, the number of cells, vessels and cell morphology scores at the defect sites increased in the FGF-2 group and decreased in the FGFRI group at 2 and 4 weeks postoperatively. In the motor functional evaluation, the FGF-2 group showed earlier improvement in the BBB score and the treadmill test compared to the control and FGFRI groups. The MTS assay showed that the number of viable cells was higher in the FGF-2 group and lower in the FGFRI group than in the control. Wound closure assay showed tenocyte migration was increased in the FGF-2 group and decreased in the FGFRI group. Regarding protein expression, Tnmd, Collagen I, III, and Screlaxis-A were increased in the FGF-2 group and decreased in the FGFRI group. Conclusion: In vivo, FGF-2 promoted healing of Achilles tendon injury, and FGFRI impeded it in terms of motor function and histology. Additionally, in vitro, FGF-2 promoted the proliferation and migration of tenocytes and enhanced extracellular matrix production, while FGFRI diminished these effects. Although native FGF-2 is produced at the injured site, further administration of FGF-2 accelerated Achilles tendon injury healing, while inhibiting the FGF receptor delayed recovery in this study. Therefore, FGF- 2 is very important in Achilles tendon injury healing and may promote recovery by enhancing angiogenesis, proliferation, and extracellular matrix production of tenocytes.

Incidence of Postoperative Rerupture of Achilles Tendon and Associated Risk Factors in South Korea: A National Population-Based Study

Category: Sports; Ankle Introduction/Purpose: Achilles tendon rerupture (ATRR) is a frequently occurring complication following the treatment of an Achilles tendon rupture (ATR) that can lead to disability; however, comprehensive risk factors for the development of postoperative ATRR remain unclear. We aimed to determine the incidence rate of postoperative ATRR and its associated risk factors, including comorbidities and medication, among the South Korean population. Methods: This study was performed based on Health Insurance Review and Assessment claims data, which covers 98% of the overall Korean population. Patients with ATR were identified according to the disease code S86.0 (Achilles tendon injury) of the Korean classification of disease between 2007 and 2020, and a washout period of 1 year was set. Instances of reoperation on the Achilles tendon between 42 and 365 days after the initial surgery, in the absence of infection or skin necrosis, were classified as cases of Achilles tendon rerupture (ATRR). Data on age, sex, comorbidities, and medications were collected and statistically analyzed. Results: Between 2009 and 2018, the incidence of surgical treatment for primary ATR was 9.91 per 100,000 person-years, showing a significant annual increase. The postoperative rerupture rate was 2.14% and did not show a significant increase. Male sex, young age, preexisting Achilles tendinopathy, osteoarthritis, and preoperative exposure to non-steroidal anti-inflammatory drugs and opioids were risk factors for postoperative ATRR. Conclusion: This information needs to be considered when determining the surgical treatment for patients with Achilles tendon rupture. The study results provoke further biological and clinical research on the risk factors for postoperative ATRR.

An Atelocollagen Injection Enhances the Healing of Nonoperatively Treated Achilles Tendon Tears: An Experimental Study in Rats.

There is growing interest in nonoperative treatment for the management of Achilles tendon ruptures (ATRs). However, nonoperative treatment is limited by the risk of tendon reruptures and low satisfaction rates. Recently, atelocollagen injections have been reported to have beneficial effects on tendon healing. To evaluate the beneficial effects of injected atelocollagen on Achilles tendon healing and investigate the mechanism of atelocollagen on tendon healing. Controlled laboratory study. Percutaneous tenotomy of the right Achilles tendon in 66 rats was performed. The animals were equally divided into the noninjection group (NG) and the collagen injection group (CG). At 1, 3, and 6 weeks, the Achilles functional index, cross-sectional area, load to failure, stiffness, stress, and the modified Bonar score were assessed. Transmission electron microscopy, western blotting, and immunohistochemistry were also performed. The Achilles functional index (-6.8 vs -43.0, respectively; P = .040), load to failure (42.1 vs 27.0 N, respectively; P = .049), and stiffness (18.8 vs 10.3 N/mm, respectively; P = .049) were higher in the CG than those in the NG at 3 weeks. There were no significant differences in histological scores between the 2 groups. Transmission electron microscopy analysis showed that the mean diameter of collagen fibrils in the CG was greater than that in the NG at 3 weeks (117.2 vs 72.6 nm, respectively; P < .001) and 6 weeks (202.1 vs 144.0 nm, respectively; P < .001). Western blot analysis showed that the expression of collagen type I in the CG was higher than that in the NG at 1 week (P = .005) and 6 weeks (P = .001). An atelocollagen injection had beneficial effects on the healing of nonoperatively treated Achilles tendon injuries. The Achilles tendon of CG rats exhibited better functional, biomechanical, and morphological outcomes compared with NG rats. The molecular data indicated that the mechanism of atelocollagen injections may be associated with an increased amount of collagen type I. An atelocollagen injection might be a good adjuvant option for the nonoperative treatment of ATRs.

Inversely engineered biomimetic flexible network scaffolds for soft tissue regeneration.

Graft-host mechanical mismatch has been a longstanding issue in clinical applications of synthetic scaffolds for soft tissue regeneration. Although numerous efforts have been devoted to resolve this grand challenge, the regenerative performance of existing synthetic scaffolds remains limited by slow tissue growth (comparing to autograft) and mechanical failures. We demonstrate a class of rationally designed flexible network scaffolds that can precisely replicate nonlinear mechanical responses of soft tissues and enhance tissue regeneration via reduced graft-host mechanical mismatch. Such flexible network scaffold includes a tubular network frame containing inversely engineered curved microstructures to produce desired mechanical properties, with an electrospun ultrathin film wrapped around the network to offer a proper microenvironment for cell growth. Using rat models with sciatic nerve defects or Achilles tendon injuries, our network scaffolds show regenerative performances evidently superior to that of clinically approved electrospun conduit scaffolds and achieve similar outcomes to autologous nerve transplantation in prevention of target organ atrophy and recovery of static sciatic index.

One Step Double Augmentation with Human Dermis Allograft and Homologous PRP in Misdiagnosed and or Chronic Achilles Tendon Ruptures.

Misdiagnosed/chronic Achilles tendon injuries are rare and disabling for patients. The surgical treatment of these rare injuries aims to ensure the tendon heals mechanically and biologically. This is the prerequisite for a good clinical and functional outcome and reduces recurrences. The main aim of the study is to present a surgical technique that has proven to be original, reproducible, and capable of guaranteeing solid tendon repair and optimal tissue regeneration. We treated five patients, four males and one female, with the one-step double augmentation technique. All patients of this study complained of pain, but above all severe functional limitation that Achilles tendon injury had been causing for more than a month. In this study, we widely described the surgical technique, original and not found in the literature, which provides a biological graft (allograft of decellularized dermis) and homologous, thrombin-activated, platelet-rich plasma (H-PRP) in a single step. Surgical approach, always used by the first author, respected predefined steps: careful dissection and preparation of the peritendinous tissues from suture to the end of the procedure, tenorrhaphy, and augmentation with allopatch to obtain a mechanically effective repair to avoid recurrences, and finally "biological" augmentation with a unit of homologous, thrombin activated, PRP. We offered to all patients a regenerative rehabilitation program post-operatively. All patients were evaluated clinically (functional clinical tests and questionnaires) and instrumentally (elastic-sonography and perfusion MRI). The obtained results have been evaluated at a minimum follow-up of 18 months and a maximum of 24 months. In all patients pain was resolved, and district function and kinetic chains improved with resumption of daily activities, work, and sports. The present study confirmed the regenerative potential of decellularized dermis allograft and PRP (homologous and thrombin-activated). The same approach can also be exploited in cases of severe tendon destructuring and limited "intrinsic" regenerative potential at any age. The proposed one-step surgical technique of a double augmentation therefore appears useful, safe, reproducible, and applicable in all chronic tendon lesions with low regenerative potential.

Methods of Immobilization after Achilles Tendon Rupture Repair: A Comparative Study in Rat Model.

The Achilles tendon (AT) is the most frequently ruptured in the human body. Literature describing different immobilization methods' impact on tendon healing after AT repair is lacking. We compare plaster cast, splint, and K-wire to determine which is the most stable and has the fewest complications. Sixty rats aged 5-6 months were selected to establish Achilles tendon injury in two hind legs model. After suturing the ends of the AT together with a modified "Kessler" method (Prolene 5-0). The skin incision was interrupted and sutured with 1-0 thread. Rats were divided into three immobilization methods (plaster cast group, splint group, and K-wire group). In plaster cast group, the hind leg was cast with plaster in the extended position of the hip and knee joints, and the ankle joint was at 150°. Splint and K-wire group used splints and 0.8-mm K-wires, separately. The fixed period was 4 weeks. The incidence of stability and complications (death, necrosis of the legs, necrosis of the skin, and incisional infection) were recorded. Differences were detected using the chi-square test. Within 4 weeks observation, K-wires showed better stability (90%) compared with the other two ways (40% in plaster cast group, 65% in splint group; p < 0.05). Rats immobilized with K-wires (10%) suffered significantly lower complications compared with plaster cast and splint group (15%; p < 0.05). K-wire has better stability, lower complication rate than other methods. Immobilization with K-wire may be a promising tool in future clinical Achilles tendon rupture applications.

Growth factors in the treatment of Achilles tendon injury.

Achilles tendon (AT) injury is one of the most common tendon injuries, especially in athletes, the elderly, and working-age people. In AT injury, the biomechanical properties of the tendon are severely affected, leading to abnormal function. In recent years, many efforts have been underway to develop effective treatments for AT injuries to enable patients to return to sports faster. For instance, several new techniques for tissue-engineered biological augmentation for tendon healing, growth factors (GFs), gene therapy, and mesenchymal stem cells were introduced. Increasing evidence has suggested that GFs can reduce inflammation, promote extracellular matrix production, and accelerate AT repair. In this review, we highlighted some recent investigations regarding the role of GFs, such as transforming GF-β(TGF-β), bone morphogenetic proteins (BMP), fibroblast GF (FGF), vascular endothelial GF (VEGF), platelet-derived GF (PDGF), and insulin-like GF (IGF), in tendon healing. In addition, we summarized the clinical trials and animal experiments on the efficacy of GFs in AT repair. We also highlighted the advantages and disadvantages of the different isoforms of TGF-β and BMPs, including GFs combined with stem cells, scaffolds, or other GFs. The strategies discussed in this review are currently in the early stages of development. It is noteworthy that although these emerging technologies may potentially develop into substantial clinical treatment options for AT injury, definitive conclusions on the use of these techniques for routine management of tendon ailments could not be drawn due to the lack of data.

117 Achilles Tendon Rupture Clinic, a Successful and Reproducible Model

Abstract Background In the view of busy Emergency departments and general fracture clinics, a delay in the assessment, diagnosis and treatment of Achilles tendon injuries can lead to poor outcomes. A dedicated Achilles tendon rupture clinic can provide efficient care and avoid such complications. Aim To assess the efficiency of the dedicated Achilles tendon rupture clinic (model) in avoiding delay in the assessment and management of Achilles tendon injuries. Method Analysis of retrospectively collected data of the patients who have been reviewed in the Achilles clinic. All patients had Ultrasound scan (USS) by trained Orthopaedic surgeons to assess the size of the gap. Non operative treatment followed an approved functional rehabilitation protocol in the department. Data for analysis included : demographic data, Time interval between injury and assessment in the Achilles clinic ,size of the gap (USS) and ATRS (The Achilles tendon Total Rupture Score ). Results 45 patients have been reviewed in the Achilles tendon rupture clinic over nine months, the mean age was 52.05 the mean time interval between referral and assessment in the Achilles clinic was 6.1 days (SD 3.59 ), The mean size of the tear was 10.65 mm (SD 5.95). The mean ATSR score at three months follow up was 70.29 ( SD 15.3). Conclusions The model of dedicated Achilles tendon rupture clinic including on-site USS can help deliver a safe and more efficient arm of the trauma service to patients and avoid delay in management that might affect the patients functional outcome and require complex surgical procedures.

Preclinical tendon and ligament models: Beyond the 3Rs (replacement, reduction, and refinement) to 5W1H (why, who, what, where, when, how).

Several tendon and ligament animal models were presented at the 2022 Orthopaedic Research Society Tendon Section Conference held at the University of Pennsylvania, May 5 to 7, 2022. A key objective of the breakout sessions at this meeting was to develop guidelines for the field, including for preclinical tendon and ligament animal models. This review summarizes the perspectives of experts for eight surgical small and large animal models of rotator cuff tear, flexor tendon transection, anterior cruciate ligament tear, and Achilles tendon injury using the framework: "Why, Who, What, Where, When, and How" (5W1H). A notable conclusion is that the perfect tendon model does not exist; there is no single gold standard animal model that represents the totality of tendon and ligament disease. Each model has advantages and disadvantages and should be carefully considered in light of the specific research question. There are also circumstances when an animal model is not the best approach. The wide variety of tendon and ligament pathologies necessitates choices between small and large animal models, different anatomic sites, and a range of factors associated with each model during the planning phase. Attendees agreed on some guiding principles including: providing clear justification for the model selected, providing animal model details at publication, encouraging sharing of protocols and expertise, improving training of research personnel, and considering greater collaboration with veterinarians. A clear path for translating from animal models to clinical practice was also considered as a critical next step for accelerating progress in the tendon and ligament field.

The effect of caffeic acid on tendon healing in rats with an Achilles tendon injury model.

This study aims to examine the effect of caffeic acid on tendon healing histopathologically and biomechanically in rats with an Achilles tendon injury model. Twenty male Wistar-albino rats were used in this study. The rats were divided into two groups as the experimental group and control group. All rats underwent a bilateral achillotomy injury model and then surgical repair. Postoperatively, for four weeks, the experimental group was given intraperitoneal caffeic acid (100 mg/kg/day suspended in saline), while the control group was given only intraperitoneal saline. At the end of four weeks, after sacrificing each rat, right Achilles tendons were subjected to biomechanical analysis and the Achilles tendons were subjected to histopathological analysis. Bonar and Movin scores were used for histopathological analysis. In biomechanical analysis, tensile test was applied to Achilles tendons until rupture. For each tendon, failure load, displacement, cross-sectional area, maximum energy, total energy, length, stiffness, ultimate stress and strain parameters were recorded. According to Bonar and Movin scoring, the experimental group had lower scoring values than the control group (p=0.002 and p=0.002, respectively). Bonar scoring parameters were analyzed separately. Vascularity, collagen, and ground substance scores were lower in the experimental group compared to the control group (p=0.001, p=0.003, and p=0.047, respectively). No significant difference was found for tenocyte (p=0.064). In biomechanical analysis, failure load, displacement, ultimate stress, strain, and stiffness values were found to be higher in the experimental group compared to the control group (p=0.049, p=0.005, p=0.028, p=0.021, and p=0.049, respectively). The caffeic acid contributed positively to tendon healing histopathologically and biomechanically in rats with an Achilles tendon injury model.

Running-Related Achilles Tendon Injury: A Prospective Biomechanical Study in Recreational Runners.

There are relatively few running studies that have attempted to prospectively identify biomechanical risk factors associated with Achilles tendon (AT) injuries. Therefore, the aim was to prospectively determine potential running biomechanical risk factors associated with the development of AT injuries in recreational, healthy runners. At study entry, 108 participants completed a set of questionnaires. They underwent an analysis of their running biomechanics at self-selected running speed. The incidence of AT running-related injuries (RRI) was assessed after 1-year using a weekly questionnaire standardized for RRI. Potential biomechanical risk factors for the development of AT RRI injury were identified using multivariable logistic regression. Of the 103 participants, 25% of the sample (15 males and 11 females) reported an AT RRI on the right lower limb during the 1-year evaluation period. A more flexed knee at initial contact (odds ratio = 1.146, P = .034) and at the midstance phase (odds ratio = 1.143, P = .037) were significant predictors for developing AT RRI. The results suggested that a 1-degree increase in knee flexion at initial contact and midstance was associated with a 15% increase in the risk of an AT RRI, thus causing a limitation of training or a stoppage of running in runners.

Macrophage-Derived Extracellular DNA Initiates Heterotopic Ossification.

Heterotopic ossification (HO) severely affects people's lives; however, its pathological mechanism remains poorly understood. Although extracellular DNA (ecDNA) has been shown to play important roles in pathological calcification, its effects in HO development and progression remain unknown. The in vivo rat Achilles tendon injury model and in vitro collagen I calcification model were used to evaluate the effects of ecDNA in the ectopic calcifications and the main cell types involved in those pathological process. Histology, immunofluorescent staining, reverse transcriptase-polymerase chain reaction analysis and micro-computed tomography were used to identify the distribution of macrophage-derived ecDNA and elucidate their roles in HO. The results showed that the amount of ecDNA and ectopic calcification increased significantly and exhibited a strong correlation in the injured tendons of HO model compared with those of the controls, which was accompanied by a significantly increased number of M2 macrophages in the injured tendon. During in vitro co-culture experiments, M2 macrophages calcified the reconstituted type I collagen and ectopic bone collected from the injured tendons of HO rats, while those effects were inhibited by deoxyribonuclease. More importantly, deoxyribonuclease reversed the pathological calcification in the injured rat tendon HO model. The present study showed that ecDNA from M2 macrophages initiates pathological calcification in HO, and the elimination of ecDNA might be developed into a clinical strategy to prevent ectopic mineralization diseases. The use of deoxyribonuclease for the targeted degradation of ecDNA at affected tissue sites provides a potential solution to treat diseases associated with ectopic mineralization.

Chronological Changes in the Expression and Localization of Sox9 between Achilles Tendon Injury and Functional Recovery in Mice.

Tendons help transmit forces from the skeletal muscles and bones. However, tendons have inferior regenerative ability compared to muscles. Despite studies on the regeneration of muscles and bone tissue, only a few have focused on tendinous tissue regeneration, especially tendon regeneration. Sex-determining region Y-box transcription factor 9 (Sox9) is an SRY-related transcription factor with a DNA-binding domain and is an important control factor for cartilage formation. Sox9 is critical to the early-to-middle stages of tendon development. However, how Sox9 participates in the healing process after tendon injury is unclear. We hypothesized that Sox9 is expressed in damaged tendons and is crucially involved in restoring tendon functions. We constructed a mouse model of an Achilles tendon injury by performing a 0.3 mm wide partial excision in the Achilles tendon of mice, and chronologically evaluated the function restoration and localization of the Sox9 expressed in the damaged sites. The results reveal that Sox9 was expressed simultaneously with the formation of the pre-structure of the epitenon, an essential part of the tendinous tissue, indicating that its expression is linked to the functional restoration of tendons. Lineage tracing for Sox9 expressed during tendon restoration revealed the tendon restoration involvement of cells that switched into Sox9-expressing cells after tendon injury. The stem cells involved in tendon regeneration may begin to express Sox9 after injury.

Clinical Management of Achilles Tendon Injury with Tendon Gap Defect in a Horse Using Tissue Engineering: A Case Report

Clinical Management of Achilles Tendon Injury with Tendon Gap Defect in a Horse Using Tissue Engineering: A Case Report

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

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

Are commercial genetic injury tests premature?

Several direct-to-consumer (DTC) genetic testing companies have emerged that claim to be able to test for susceptibility for musculoskeletal injuries. Although there are several publications on the emergence of this industry, none have critically evaluated the evidence for the use of genetic polymorphisms in commercial tests. The aim of this review was to identify, where possible, the polymorphisms and to evaluate the current scientific evidence for their inclusion. The most common polymorphisms included COL1A1 rs1800012, COL5A1 rs12722, and GDF5 rs143383. The current evidence suggests that it is premature or even not viable to include these three polymorphisms as markers of injury risk. A unique set of injury-specific polymorphisms, which do not include COL1A1, COL5A1, or GDF5, identified from genome-wide association studies (GWAS) is used by one company in their tests for 13 sports injuries. However, of the 39 reviewed polymorphisms, 22 effective alleles are rare and absent in African, American, and/or Asian populations. Even when informative in all populations, the sensitivity of many of the genetic markers was low and/or has not been independently validated in follow-up studies. The current evidence suggests it is premature to include any of the reviewed polymorphisms identified by GWAS or candidate gene approaches in commercial genetic tests. The association of MMP7 rs1937810 with Achilles tendon injuries, and SAP30BP rs820218 and GLCCI1 rs4725069 with rotator cuff injuries does warrant further investigation. Based on current evidence, it remains premature to market any commercial genetic test to determine susceptibility to musculoskeletal injuries.

Presurgical Perspectives and Post-treatment Evaluation of Achilles Tendon Injuries.

The Achilles is a commonly injured tendon, prone to degeneration and tear. Achilles tendon treatment ranges from conservative management to injections, tenotomy, open versus percutaneous tendon repair, graft reconstruction, and flexor hallucis longus transfer. Interpreting postoperative imaging of the Achilles tendon is a difficult task for many providers. This article clarifies these issues by presenting the imaging findings following standard treatments and depicts expected appearance versus recurrent tear and other complications.

Analytical relationships for 2D Re-entrant auxetic metamaterials: An application to 3D printing flexible implants

Both 2D and 3D re-entrant designs are among the well-known prevalent auxetic structures exhibiting negative Poisson's ratio. The present study introduces novel analytical relationships for 2D re-entrant hexagonal honeycombs for both negative and positive ranges of the cell interior angle θ (θ<0 showing a negative Poisson's ratio). The derived analytical solutions are validated against finite element method (FEM) and experimental results. The results show that, compared to the analytical solutions available in the literature, the analytical relationships presented in this study provide the most accurate results for elastic modulus, Poisson's ratio, and yield stress. The analytical/computational tools are then implemented for designing Kinesio taping (KT) structures applicable to treatment of Achilles tendon injuries. One of the main features of the Achilles tendon is a natural auxetic behavior. Poisson's ratio distribution of an Achilles tendon is obtained using longitudinal and transverse strains and are then used to design and 3D print thermoplastic polyurethane (TPU) KT structures with non-uniform distribution of auxetic unit cells. The presented novel KT shows that it is capable of replicating the deformation and global and local Poisson's ratio distributions, similar to those of the Achilles tendon. Due to the absence of similar formulations and procedures in the literature, the results are expected to be instrumental for designing and 3D printing of flexible implants with unusual auxeticity.

Achilles Tendon Injuries in the Pediatric Population.

Achilles tendon injuries are common in adults, and there is extensive literature describing the injury characteristics and treatment of these adult injuries. However, Achilles injuries are rare in the pediatric population and as a result, there is limited research reported on this age group. We therefore sought to characterize the injury presentation, treatment and outcomes for pediatric patients with partial and complete Achilles injuries. A retrospective chart review was conducted of patients aged 0-18 treated for Achilles tendon injuries at 2 geographically distinct tertiary institutions between 2008 and 2021. Data collected included demographics, injury characteristics, and treatment course. Injury types were separated into 2 cohorts: traumatic Achilles injuries and ruptures due to muscular contraction. Traumatic injuries were further delineated into 2 injury mechanisms: open injuries related to penetrating trauma and closed injuries related to blunt trauma. Standard descriptive analyses were utilized to summarize findings. Thirty-nine patients (43.6% female, median age 15 years) were identified, 29 (74.4%) of whom had complete tears. Twenty-five patients (64.1%) presented with traumatic injuries; among these, 48.0% (n=12/25) were ≤12 years. All patients ≤12 years sustained a traumatic injury. The most common traumatic mechanism was an open laceration due to penetrating trauma (68.0%), followed by closed ruptures associated with blunt trauma (32.0%). Fourteen patients (35.9%) presented with closed ruptures due to muscular contraction. Four patients (10.2%) had a prior history of clubfoot treated with Achilles tenotomy. Thirty-five patients (89.7%) were surgically treated with an open repair. The median immobilization period across all patients was 11 weeks (interquartile range: 10-12), starting most commonly with a posterior splint (46.2%) and concluding with a CAM boot (94.9%). Of patients with full follow-up data (n=22/39), all resumed normal activities, with a median clearance time of 6 months (interquartile range: 5-7.9). We found that older adolescents (≥14y) were more likely to rupture their Achilles tendon through a forceful muscular contraction, whereas younger patients (≤12y) were more likely to injure their Achilles via a traumatic mechanism. Most patients were treated operatively and returned to sports at a median time of 6 months. A further prospective study is warranted to better characterize treatment protocols and patient outcomes in this population. Level-IV.

Pro-inflammatory activity of long noncoding RNA FOXD2-AS1 in Achilles tendinopathy

Achilles tendinopathy is a prevalent clinical problem that plagues athletes and general populations. Achilles tendon healing is a complex process, and so far, there is no successful long-term solution to Achilles tendinopathy in the field of microsurgery due to its poor natural regeneration ability. Limitations in understanding the pathogenesis of Achilles tendon development and Achilles tendon injury hinder clinical treatment developments. There is an increasing demand for innovative conservative treatments that can improve Achilles tendon injury. In this study, a Sprague–Dawley rat model of Achilles tendinopathy was established. Lentiviral vectors that interfere with the expression of FOXD2-AS1, miR-21-3p, or PTEN were injected every 3 days. Rats were euthanized after 3 weeks, and the effect of FOXD2-AS1, miR-21-3p, or PTEN on Achilles tendon healing was analyzed by histological observation, biomechanical test, and examinations of inflammatory factors and tendon markers. As measured, downregulating FOXD2-AS1 or upregulating miR-21-3p improved histological structure, suppressed inflammation, promoted the expression of tendon markers, and optimized the biomechanical properties of Achilles tendon. Upregulating PTEN was capable of reversing the promoting effect of inhibition of FOXD2-AS1 on Achilles tendon healing. As concluded, deficiency of FOXD2-AS1 accelerates the healing of Achilles tendon injury and improves tendon degeneration by regulating the miR-21-3p/PTEN axis and promoting the activation of the PI3K/AKT signaling pathway.