Can the Achilles tendon regenerate completely following percutaneous tenotomy in older children with clubfoot?

PURPOSE: The aims of the study were to document the outcomes of percutaneous Achilles tenotomy (pAT) performed in older children with clubfoot, by assessing the clinical, functional and ultrasonographic evidence of Achilles tendon regeneration. METHODS: A retrospective case series of older children with clubfoot treated between August 2011 and July 2020 was studied. Clinical assessment of ankle range of motion and calf strength, functional assessment of triceps surae muscle endurance by single leg heel-rise test, and ultrasonographic assessment of Achilles tendon echotexture and dimensions to assess tendon regeneration were performed. RESULTS: Percutaneous Achilles tenotomy was performed on 31 children (48 clubfeet) at a mean age of 5.24 ± 2.14 years (1-10.2 years). At a mean follow-up of 4.86 ± 1.97 years, all children demonstrated normal calf strength with mean dorsiflexion range of 13.64° (0-25°) and mean plantarflexion range of 37.95° (10-40°). The heel-rise endurance test was completed by 27 children with mean 25.85 heel rises/minute (range 17-30) and mean height of heel rise of 6.29 cm (range 4-10 cm). Normal fibrillar tendinous echotexture with homogenous echogenicity was seen on ultrasonography in 41 feet (85.4%) with mean tendon width of 9.7 mm (3.3-16 mm) and thickness of 5.1 mm (1.8-15 mm), comparable with unaffected feet. CONCLUSIONS: Clinical, functional and ultrasonographic parameters unequivocally demonstrate complete regeneration of the Achilles tendon, when pAT is performed in older children with delayed-presenting idiopathic clubfoot treated using Ponseti principles.

Double-Row Achilles Insertional Repair With Rip-Stop Increases Construct Strength Compared to Traditional Techniques: A Biomechanical Study.

BACKGROUND: Although double-row suture-anchored (DRSA) techniques for Achilles insertional tendinosis has proven successful, a reoccurring failure mode not yet addressed is suture tearing through the tendon. This study aims to address suture tearing by incorporating a rip-stop element. Authors hypothesized that the Rip-Stop group would demonstrate increased strength compared with more traditional techniques. METHODS: 12 paired cadaveric feet were used in this study (n = 24). One sample from each pair was assigned to receive the standard double-row (SDR) Achilles repair with 4.75-mm knotless anchors (n = 12). The control's matched sides were divided between 2 DRSA bridge groups: modified double-row (MDR) bridge with 3.9-mm anchors or rip-stop double-row (RS-DR) bridge repair with soft proximal anchors and 3.9-mm anchored distal row. In neutral position, specimens underwent 1000 cycles (20-100 N) followed by load to failure. Displacements, stiffness, ultimate load, and failure mode were recorded. RESULTS: RS-DR had the lowest initial displacement values followed by SDR and MDR (1.3 ± 0.4, 2.7 ± 1.4, and 3.2 ± 1.3 mm, respectively). Significance was detected when comparing initial displacement of RS-DR to MDR (P = .038). Cyclic displacement was lowest for RS-DR, followed by MDR and SDR (1.6 ± 0.9, 2.2 ± 1.1, and 4.5 ± 3.2 mm, respectively). Cyclic stiffness was similar for RS-DR and MDR (89.1 ± 24.6 and 81.9 ± 5.6 N/mm, respectively). RS-DR ultimate load (1116.8 ± 405.7 N) was statistically greater than SDR (465.6 ± 352.7, P = .003). CONCLUSION: RS-DR-repaired specimens demonstrated a decrease in displacement values and increased ultimate load and stiffness when compared to other groups. Results of this cadaveric model suggest that the addition of a rip-stop to DRSA Achilles repair is more impactful than anchor size. Limitations include that this was a time-zero biomechanical study, which cannot simulate the performance of the repairs during postoperative healing and recovery. CLINICAL RELEVANCE: A rip-stop technique for Achilles repair effectively improves dynamic mechanical characteristics and may mitigate suture tearing through tendon in a patient cohort.

Human Achilles tendon mechanical behavior is more strongly related to collagen disorganization than advanced glycation end-products content.

Diabetes is associated with impaired tendon homeostasis and subsequent tendon dysfunction, but the mechanisms underlying these associations is unclear. Advanced glycation end-products (AGEs) accumulate with diabetes and have been suggested to alter tendon function. In vivo imaging in humans has suggested collagen disorganization is more frequent in individuals with diabetes, which could also impair tendon mechanical function. The purpose of this study was to examine relationships between tendon tensile mechanics in human Achilles tendon with accumulation of advanced glycation end-products and collagen disorganization. Achilles tendon specimens (n = 16) were collected from individuals undergoing lower extremity amputation or from autopsy. Tendons were tensile tested with simultaneous quantitative polarized light imaging to assess collagen organization, after which AGEs content was assessed using a fluorescence assay. Moderate to strong relationships were observed between measures of collagen organization and tendon tensile mechanics (range of correlation coefficients: 0.570-0.727), whereas no statistically significant relationships were observed between AGEs content and mechanical parameters (range of correlation coefficients: 0.020-0.210). Results suggest that the relationship between AGEs content and tendon tensile mechanics may be masked by multifactorial collagen disorganization at larger length scales (i.e., the fascicle level).

Achilles Tendinopathy, A Brief Review and Update of Current Literature.

ABSTRACT: Chronic pain in the Achilles tendon is a common problem in both athletes and nonathletes alike. The etiology for the development of Achilles tendinopathy has not been fully elucidated, and there remains multiple theories to explain the pain and dysfunction accompanying this condition. The diagnosis of Achilles tendon problems continues to rely on the clinical history and physical examination. The optimal management of pain, restoration of function, and return-to-sports participation with Achilles tendinopathy are evolving because of the advancement in technologies and research regarding its pathophysiology. This article aims to provide a brief review of the relevant anatomy, differential diagnosis, imaging findings, and an update of the literature on conservative and minimally invasive managements of chronic Achilles tendinopathy.

Assessment of Functional Conservative Treatment of Acute Complete Achilles Tendon Rupture.

BACKGROUND: In recent years, treatment for Achilles tendon rupture (ATR) went through radical changes: from the conservative non-weight bearing approach to a functional protocol. This functional protocol allows complete weight bearing after only 2 weeks by placing the foot in a plastic boot in tapered down equines and using interchangeable wedges under the heel. This change of approach has dramatically lowered the rate of re-rupture. OBJECTIVES: To describe our preliminary results with this functional protocol and to assess outcome measures in the functional conservative treatment. METHODS: The study comprised 15 people who were evaluated clinically and by sonograph. We measured calf circumference, ankle joint range of motion (ROM), and single-leg heel-rise test (SLHRT). In addition, standard scoring methods (Achilles Tendon Rupture Score and Physical Activity Scale) were examined. RESULTS: In our cohort 14 people successfully gained SLHRT. The mean Achilles Tendon Rupture Score functional questionnaire and Physical Activity Scale physical activity questionnaire score was 85.6 of 100, and 4.7 of 6, respectively. There were no significant differences in ankle ROM compared to the uninjured limb. There was statistically significant reduction in the calf circumference and soleus muscle thickness sonographically. CONCLUSIONS: It seems that the conservative functional treatment of ATR demonstrates good functional outcomes, with the patients returning to close to normal activity, although noted muscle wasting and weakness. This protocol presents a true alternative to surgery and should be considered for most non-insertional Achilles tendon tears.

Grafting of iPS cell-derived tenocytes promotes motor function recovery after Achilles tendon rupture.

Tendon self-renewal is a rare occurrence because of the poor vascularization of this tissue; therefore, reconstructive surgery using autologous tendon is often performed in severe injury cases. However, the post-surgery re-injury rate is relatively high, and the collection of autologous tendons leads to muscle weakness, resulting in prolonged rehabilitation. Here, we introduce an induced pluripotent stem cell (iPSC)-based technology to develop a therapeutic option for tendon injury. First, we derived tenocytes from human iPSCs by recapitulating the normal progression of step-wise narrowing fate decisions in vertebrate embryos. We used single-cell RNA sequencing to analyze the developmental trajectory of iPSC-derived tenocytes. We demonstrated that iPSC-tenocyte grafting contributed to motor function recovery after Achilles tendon injury in rats via engraftment and paracrine effects. The biomechanical strength of regenerated tendons was comparable to that of healthy tendons. We suggest that iPSC-tenocytes will provide a therapeutic option for tendon injury.

Static foot posture and its relation to clinical variables in ankylosing spondylitis.

AIM: Postural abnormalities of the foot are common in rheumatic diseases. Static foot posture is a poorly studied clinical parameter in ankylosing spondylitis (AS). The aim of the study was to evaluate static foot posture in patients with AS and to determine the potential impact of clinical variables on foot posture. METHOD: Fifty patients with AS and 40 age- and sex-matched healthy controls were enrolled in the study. Disease activity was measured using the Ankylosing Spondylitis Disease Activity Score. Axial mobility was evaluated with the Bath Ankylosing Spondylitis Metrology Index three-point answer scale. Functional status was assessed by the Bath Ankylosing Spondylitis Functional Index and Health Assessment Questionnaire-Disability Index. Enthesitis and foot posture were evaluated by the Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) and Foot Posture Index-6, respectively. RESULTS: Patients with AS revealed significantly higher scores of foot posture index when compared with controls (P = 0.005). Abnormal foot posture (pronated and supinated) was more common in the patient group (P < 0.01). According to the multinomial logistic regression analysis, a higher MASES score was associated with supinated foot posture in AS patients (odds ratio 1.47, 95% confidence interval 1.03-2.09, P = 0.035). In addition, supinated foot posture was associated with enthesitis of the Achilles tendon (P = 0.002). CONCLUSION: Enthesitis is related to deteriorated static foot posture in patients with AS. Enthesitis of the Achilles tendon is closely associated with the supinated foot posture.

Beyond the Diagnosis: Using Patient Characteristics and Domains of Tendon Health to Identify Latent Subgroups of Achilles Tendinopathy.

OBJECTIVE: To identify latent subgroups among patients with Achilles tendinopathy, describe patient characteristics and clinical attributes that defined each subgroup, and develop a clinical classification model for subgroup membership. DESIGN: Cross-sectional study. METHODS: One hundred forty-five participants (men, n = 73; mean ± SD age, 51 ± 14 years) with clinically diagnosed Achilles tendinopathy completed a baseline evaluation, including demographics and medical history, patient-reported outcome measures, a clinical exam, tendon structure measures via ultrasound imaging and continuous shear-wave elastography, and a functional test battery. Subgroups were identified using mixture modeling. We compared the subgroups using a 1-way analysis-of-variance or chi-square test and the Tukey post hoc test to identify defining attributes. We developed a clinical classification model using logistic regression and receiver operating characteristic curves. RESULTS: Three latent subgroups were identified and named by their distinctive patient characteristics and clinical attributes. The activity-dominant subgroup (n = 67), on average, had the highest physical activity level, function, and quality of life; reported mild symptoms; and was the youngest. The psychosocial-dominant subgroup (n = 56), on average, had the worst symptoms, impaired function, heightened psychological factors, the poorest quality of life, minimal tendon structural alterations, and was obese and predominantly female. The structure-dominant subgroup (n = 22), on average, had the most tendon structural alterations, severe functional deficits, moderate symptoms and psychological factors, reduced quality of life, and was the oldest, obese, and predominantly male. The clinical classification model correctly classified 85% (123/145) of participants. CONCLUSION: Three Achilles tendinopathy subgroups (activity dominant, psychosocial dominant, and structure dominant) differed in patient characteristics and clinical attributes. J Orthop Sports Phys Ther 2021;51(9):440-448. Epub 1 Jun 2021. doi:10.2519/jospt.2021.10271.

Dutch multidisciplinary guideline on Achilles tendinopathy.

OBJECTIVE: To provide a comprehensive, evidence-based overview of the risk factors, prevention, diagnosis, imaging, treatment and prognosis for Achilles tendinopathy. To make clinical recommendations for healthcare practitioners and patients. DESIGN: Comprehensive multidisciplinary guideline process funded by the Quality Foundation of the Dutch Federation of Medical Specialists. This process included a development, commentary and authorisation phase. Patients participated in every phase. DATA SOURCES: Multiple databases and existing guidelines were searched up to May 2019. Information from patients, healthcare providers and other stakeholders were obtained using a digital questionnaire, focus group interview and invitational conference. STUDY ELIGIBILITY CRITERIA: Studies on both insertional and/or midportion Achilles tendinopathy were eligible. Specific eligibility criteria were described per module. DATA EXTRACTION AND SYNTHESIS: To appraise the certainty of evidence, reviewers extracted data, assessed risk of bias and used the Grading of Recommendations Assessment, Development and Evaluation method, where applicable. Important considerations were: patient values and preferences, costs, acceptability of other stakeholders and feasibility of implementation. Recommendations were made based on the results of the evidence from the literature and the considerations. PRIMARY OUTCOME MEASURE: The primary and secondary outcome measures were defined per module and defined based on the input of patients obtained in collaboration with the Netherlands Patient Federation and healthcare providers from different professions. RESULTS: Six specific modules were completed: risk factors and primary prevention, diagnosis, imaging, treatment prognosis and secondary prevention for Achilles tendinopathy. SUMMARY/CONCLUSION: Our Dutch multidisciplinary guideline on Achilles tendinopathy provides six modules developed according to the standards of the Dutch Federation of Medical Specialists. Evidence-based recommendations for clinical practice are given for risk factors, prevention, diagnosis, imaging, treatment and prognosis. This guideline can assist healthcare providers and patients in clinical practice.

Effects of kinesiophobia and pain on performance and willingness to perform jumping tests in Achilles tendinopathy: A cross-sectional study.

OBJECTIVES: Fear of movement may be a source of systemic bias in studies reporting functional deficits in patients with Achilles tendinopathy. The purpose of this study was to assess the effects of kinesiophobia on completion rate and performance on tests evaluating lower extremity function, while controlling for self-reported pain. DESIGN: Cross-sectional study; SETTING: Tendon research laboratory. PARTICIPANTS: Ninety-four participants with Achilles tendinopathy. MAIN OUTCOME MEASURES: Completion (yes/no) and performance (cm) on the counter-movement jump, hopping, and drop counter-movement jump. RESULTS: The models fit the data (R^2 = 0.81, both models). TSK score did not predict completion (beta = -0.01, 95% CI = -0.13 - 0.09, P = 0.74) but pain did (beta = -0.36, 95% CI = -0.53 to -0.19, P < 0.0001). TSK score did not predict performance (beta = -0.06, 95% CI = -0.14 - 0.003, P = 0.07), but pain did (beta = -0.15, 95% CI = -0.22 to -0.07, P < 0.0001). CONCLUSIONS: Kinesiophobia did not affect the physical performance tests in patients with Achilles tendinopathy. Measures of physical performance should be interpreted alongside self-reported pain.

Shockwave Therapy Plus Eccentric Exercises Versus Isolated Eccentric Exercises for Achilles Insertional Tendinopathy: A Double-Blinded Randomized Clinical Trial.

BACKGROUND: There remains a lack of consensus regarding the treatment of Achilles insertional tendinopathy. The condition is typically treated with eccentric exercises despite the absence of satisfactory and sustained results. Shockwave therapy was presented as an alternative, but there is a paucity of literature, with good outcomes, supporting its use. The purpose of the present single-center, double-blinded, placebo-controlled, randomized trial was to determine if the use of shockwave therapy in combination with eccentric exercises improves pain and function in patients with Achilles insertional tendinopathy. METHODS: A total of 119 patients with Achilles insertional tendinopathy were evaluated and enrolled in the study from February 2017 to February 2019. Patients were allocated to 1 of 2 treatment groups, eccentric exercises with extracorporeal shockwave therapy (SWT group) and eccentric exercises with sham shockwave therapy (control group). Three sessions of radial shockwaves (or sham treatment) were performed every 2 weeks and eccentric exercises were undertaken for 3 months. The primary outcome was the Victorian Institute of Sport Assessment-Achilles questionnaire (VISA-A) at 24 weeks. Secondary outcomes included the visual analogue scale, algometry, the Foot and Ankle Outcome Score, and the 12-Item Short Form Health Survey. RESULTS: Both groups showed significant improvement during the study period; however, there were no between-group differences in any of the outcomes (all p >0.05). At the 24-week evaluation, the SWT group exhibited a mean VISA-A of 63.2 (95% confidence interval, 8.0) compared with 62.3 (95% confidence interval, 6.9) in the control group (p = 0.876). There was a higher rate of failure (38.3%) but a lower rate of recurrence (17.0%) in the SWT group compared with the control group (11.5% and 34.6%, respectively; p = 0.002 and p = 0.047). There were no complications reported for either group. CONCLUSIONS: Extracorporeal shockwave therapy does not potentiate the effects of eccentric strengthening in the management of Achilles insertional tendinopathy. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Psychological factors during rehabilitation of patients with Achilles or patellar tendinopathy: a cross-sectional study.

OBJECTIVE: to examine psychological factors during rehabilitation of patients with Achilles or patellar tendinopathy as well as the association between psychological factors and tendinopathy severity, sport participation, and satisfaction with activity level and tendon function. DESIGN: cross-sectional study. SETTING: online survey platform. PARTICIPANTS: 119 patients (mean age: 44 years (SD 14)) diagnosed with Achilles or patellar tendinopathy. MAIN OUTCOME MEASURES: A range of patient-reported psychological and outcome measures were recorded. Multivariate regression analyses were performed to establish the association between each psychological factor and outcome measures, adjusted for relevant confounders. RESULTS: Psychological readiness and confidence to return to sports (I-PRRS) and pain catastrophizing (PCS) were significantly associated with tendinopathy severity (modified VISA), sport participation(OSTRC-O), and satisfaction. Kinesiophobia (TSK) and the importance to patients of returning to pre-injury activity level were significantly associated with sports participation and satisfaction. CONCLUSION: The current study provides evidence of impairments in psychological factors during rehabilitation of patients with Achilles and patellar tendinopathy. Most investigated psychological factors were associated with tendinopathy severity, function, participation, and satisfaction. Physical therapists should recognize patients with lack of psychological readiness to return to sports and also patients with kinesiophobia or catastrophizing thoughts when experiencing pain.

Plantar soft tissues and Achilles tendon thickness and stiffness in people with diabetes: a systematic review.

BACKGROUND: Diabetes mellitus is associated with changes in soft tissue structure and function. However, the directionality of this change and the extent to which either tissue thickness or stiffness contributes to the pathogenesis of diabetes-related foot ulcerations is unclear. Hence, this systematic review aims to summarise the existing evidence for soft tissue structural differences in the feet of people with and without diabetes. METHODS: In compliance with MOOSE and PRISMA guidelines, AMED, CINAHL, MEDLINE, ProQuest Health & Medical Collection, ProQuest Nursing & Allied Health Database, and Web of Science electronic databases were systematically searched for studies published from database inception until 1st October 2020 [Prospero CRD42020166614]. Reference lists of included studies were further screened. Methodological quality was appraised using a modified critical appraisal tool for quantitative studies developed by McMaster University. RESULTS: A total of 35 non-randomised observational studies were suitable for inclusion. Within these, 20 studies evaluated plantar tissue thickness, 19 studies evaluated plantar tissue stiffness, 9 studies evaluated Achilles tendon thickness and 5 studies evaluated Achilles tendon stiffness outcomes. No significant differences in plantar tissue thickness were found between people with and without diabetes in 55% of studies (11/20), while significantly increased plantar tissue stiffness was found in people with diabetes in 47% of studies (9/19). Significantly increased Achilles tendon thickness was found in people with diabetes in 44% of studies (4/9), while no significant differences in Achilles tendon stiffness were found between people with and without diabetes in 60% of studies (3/5). CONCLUSIONS: This systematic review found some evidence of soft tissue structural differences between people with and without diabetes. However, uncertainty remains whether these differences independently contribute to diabetes-related foot ulcerations. The heterogeneity of methodological approaches made it difficult to compare across studies and methodological quality was generally inadequate. High-quality studies using standardised and validated assessment techniques in well-defined populations are required to determine more fully the role of structural tissue properties in the pathogenesis of diabetes-related foot ulcerations.

Duration of immobilisation after Achilles tendon rupture repair by open surgery: a retrospective cohort study.

BACKGROUND: The best treatment for acute Achilles tendon ruptures remains controversial. No cohort studies have compared different immobilisation durations after open surgery. This retrospective cohort study aimed to determine the optimal duration of immobilisation after this surgery. METHODS: A total of 266 patients with acute Achilles tendon rupture were divided into 4 groups (A, B, C, and D) according to immobilisation duration of 0, 2, 4, and 6 weeks, respectively. All patients underwent the same suture technique with a similar rehabilitation protocol and were examined clinically at 2, 4, 6, 8, 10, 12, 14, 16, 24, and 48 weeks, with a final follow-up at a mean of 22.3 months postoperatively. The primary outcome was the time of return to light sports activity (LSA). Secondary outcomes included range of motion (ROM) and single-legged heel rise height (SHRH). Data on operation time, complications, visual analogue pain scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score, and Achilles tendon Total Rupture score (ATRS) were also collected. Demographic baseline data were analysed using one-way analysis of variance; outcome parameters were analysed using Kruskal-Wallis H test, and complications were analysed using Fisher's exact test. Statistical significance was considered at P ≤ 0.05. RESULTS: VAS scores decreased significantly, reaching 0 in all groups after 12 weeks. The AOFAS and ATRS scores were significantly different between the groups from weeks 2 to 12 (P<0.001) and weeks 2 to 16 (P<0.001), respectively. All the mean scores showed better results in group B than in the other groups. In terms of recovery time of ROM, SHRH, and LSA, groups A and B were significantly faster than groups C and D (P<0.001). There were 13 (13/266, 4.9%) complications: 5 superficial infections, 3 deep venous thrombosis, and 5 trauma-related re-ruptures. On the last follow-up, all complications had recovered. There were no significant differences in complications between the groups. CONCLUSIONS: Immobilisation for 2 weeks after this open surgery is the best choice for early rehabilitation and weight-bearing while minimising pain and other complications.

Explaining Variability in the Prevalence of Achilles Tendon Abnormalities: A Systematic Review With Meta-analysis of Imaging Studies in Asymptomatic Individuals.

OBJECTIVE: To estimate the prevalence of, and factors associated with, Achilles tendon abnormalities observed on imaging in asymptomatic individuals. DESIGN: Systematic review with stratified meta-analysis and meta-regression. LITERATURE SEARCH: Embase, Scopus, MEDLINE, CINAHL, SPORTDiscus, and Web of Science were searched from 1980 to August 2020. STUDY SELECTION CRITERIA: We included studies that reported the prevalence of Achilles tendon abnormalities, observed with any imaging modality, in an asymptomatic population. We excluded studies if participant mean age was younger than 12 years or if participants had current/previous lower-limb tendon injuries/symptoms or other systemic conditions. DATA SYNTHESIS: Random-effects proportion meta-analysis was used to estimate prevalence. We used meta-regression for continuous variables (mean age and body mass index [BMI], sample size, proportion of female participants) and stratified categorical variables (imaging modality and participation in physical activity) to explain between-study heterogeneity. RESULTS: We included 91 studies (10 156 limbs, 5841 participants). The prevalence of Achilles tendon abnormalities on imaging ranged from 0% to 80% per participant. Between-study heterogeneity was high (I2>90%, P<.001), precluding data pooling. Between-study heterogeneity was partly explained by participant mean BMI (slope, 2.8% per 1-unit increase in BMI; 95% confidence interval: 0.57%, 5.03%; P = .015) and participation in physical activity per limb, and mean age of 40 years old or older (P = .022) per participant. CONCLUSION: There was substantial variability in the prevalence of Achilles tendon abnormalities on imaging in asymptomatic individuals. Higher prevalence of abnormalities was associated with older age (40 years old or older), higher BMI, and participation in physical activity. A large proportion of heterogeneity remains unaccounted for, likely due to variations in abnormality definitions and study design. J Orthop Sports Phys Ther 2021;51(5):232-252. Epub 28 Mar 2021. doi:10.2519/jospt.2021.9970.

Line- and Point-Focused Extracorporeal Shock Wave Therapy for Achilles Tendinopathy: A Placebo-Controlled RCT Study.

BACKGROUND: Extracorporeal shock wave therapy (ESWT) is a widely considered treatment option for Achilles tendinopathy. Line-focused ESWT is a novel technique treating a larger tendon area than point-focused ESWT. Monitoring capacities of clinical symptoms with ultrasound under ESWT treatment are unknown. HYPOTHESIS: Point- and line-focused ESWT have a superior outcome than placebo ESWT. ESWT leads to morphological tendon changes detectable with ultrasound. STUDY DESIGN: Single-blinded placebo-controlled randomized contolled trial. LEVEL OF EVIDENCE: Level 1. METHODS: The study was conducted in 3 cohorts, namely ESWT point (n = 21), ESWT line (n = 24), and ESWT placebo (n = 21). Victorian Institute of Sports Assessment-Achilles (VISA-A) score was measured before the intervention (T0), after 6 weeks (T1), and after 24 weeks (T2). All cohorts performed daily physiotherapy for 24 weeks and received 4 sessions of point-focused, line-focused, or placebo ESWT in the first 6 weeks. Ultrasound was performed with B-mode, power Doppler, shear wave elastography (SWE) at T0 and T2 and with ultrasound tissue characterization (UTC) at T0, T1, and T2. Data were analyzed with a mixed analysis of variance and t test. RESULTS: There was a significant VISA-A improvement over time for all groups (P < 0.001). ESWT point had the strongest VISA-A score improvement +23 (ESWT line: +18; ESWT placebo: +15), but there was no significant interaction between time and any of the groups: F(4, 116) = 1.393; P = 0.24. UTC, power Doppler, and B-mode could not show significant alterations over time. SWE revealed a significant increase of elastic properties for ESWT point in the insertion (t = -3.113, P = 0.03) and midportion (t = -2.627, P = 0.02) over time. CONCLUSION: There is a significant VISA-A score improvement for all study groups without a statistically significant benefit for ESWT point or ESWT line compared with ESWT placebo. Tendon adaptation could only be detected with SWE for ESWT point. CLINICAL RELEVANCE: The present study could not detect any statistically relevant effect of ESWT compared to placebo. SWE is able to demonstrate tendon adaptation.

A numerical framework for mechano-regulated tendon healing-Simulation of early regeneration of the Achilles tendon.

Mechano-regulation during tendon healing, i.e. the relationship between mechanical stimuli and cellular response, has received more attention recently. However, the basic mechanobiological mechanisms governing tendon healing after a rupture are still not well-understood. Literature has reported spatial and temporal variations in the healing of ruptured tendon tissue. In this study, we explored a computational modeling approach to describe tendon healing. In particular, a novel 3D mechano-regulatory framework was developed to investigate spatio-temporal evolution of collagen content and orientation, and temporal evolution of tendon stiffness during early tendon healing. Based on an extensive literature search, two possible relationships were proposed to connect levels of mechanical stimuli to collagen production. Since literature remains unclear on strain-dependent collagen production at high levels of strain, the two investigated production laws explored the presence or absence of collagen production upon non-physiologically high levels of strain (>15%). Implementation in a finite element framework, pointed to large spatial variations in strain magnitudes within the callus tissue, which resulted in predictions of distinct spatial distributions of collagen over time. The simulations showed that the magnitude of strain was highest in the tendon core along the central axis, and decreased towards the outer periphery. Consequently, decreased levels of collagen production for high levels of tensile strain were shown to accurately predict the experimentally observed delayed collagen production in the tendon core. In addition, our healing framework predicted evolution of collagen orientation towards alignment with the tendon axis and the overall predicted tendon stiffness agreed well with experimental data. In this study, we explored the capability of a numerical model to describe spatial and temporal variations in tendon healing and we identified that understanding mechano-regulated collagen production can play a key role in explaining heterogeneities observed during tendon healing.

Effect of storage and preconditioning of healing rat Achilles tendon on structural and mechanical properties.

Tendon tissue storage and preconditioning are often used in biomechanical experiments and whether this generates alterations in tissue properties is essential to know. The effect of storage and preconditioning on dense connective tissues, like tendons, is fairly understood. However, healing tendons are unlike and contain a loose connective tissue. Therefore, we investigated if storage of healing tendons in the fridge or freezer changed the mechanical properties compared to fresh tendons, using a pull-to-failure or a creep test. Tissue morphology and cell viability were also evaluated. Additionally, two preconditioning levels were tested. Rats underwent Achilles tendon transection and were euthanized 12 days postoperatively. Statistical analyzes were done with one-way ANOVA or Student's t-test. Tissue force and stress were unaltered by storage and preconditioning compared to fresh samples, while high preconditioning increased the stiffness and modulus (p ≤ 0.007). Furthermore, both storage conditions did not modify the viscoelastic properties of the healing tendon, but altered transverse area, gap length, and water content. Cell viability was reduced after freezing. In conclusion, preconditioning on healing tissues can introduce mechanical data bias when having extensive tissue strength diversity. Storage can be used before biomechanical testing if structural properties are measured on the day of testing.

Recovery from Achilles Tendon Repair: A Combination of Postsurgery Outcomes and Insufficient Remodeling of Muscle and Tendon.

INTRODUCTION: Achilles tendon rupture (ATR) patients have persistent functional deficits in the triceps surae muscle-tendon unit (MTU). The complex remodeling of the MTU accompanying these deficits remains poorly understood. The purpose of the present study was to associate in vivo and in silico data to investigate the relations between changes in MTU properties and strength deficits in ATR patients. METHODS: Eleven male subjects who had undergone surgical repair of complete unilateral ATR were examined 4.6 ± 2.0 (mean ± SD) yr after rupture. Gastrocnemius medialis (GM) tendon stiffness, morphology, and muscle architecture were determined using ultrasonography. The force-length relation of the plantar flexor muscles was assessed at five ankle joint angles. In addition, simulations (OpenSim) of the GM MTU force-length properties were performed with various iterations of MTU properties found between the unaffected and the affected side. RESULTS: The affected side of the patients displayed a longer, larger, and stiffer GM tendon (13% ± 10%, 105% ± 28%, and 54% ± 24%, respectively) compared with the unaffected side. The GM muscle fascicles of the affected side were shorter (32% ± 12%) and with greater pennation angles (31% ± 26%). A mean deficit in plantarflexion moment of 31% ± 10% was measured. Simulations indicate that pairing an intact muscle with a longer tendon shifts the optimal angular range of peak force outside physiological angular ranges, whereas the shorter muscle fascicles and tendon stiffening seen in the affected side decrease this shift, albeit incompletely. CONCLUSIONS: These results suggest that the substantial changes in MTU properties found in ATR patients may partly result from compensatory remodeling, although this process appears insufficient to fully restore muscle function.

Non-uniform displacement within ruptured Achilles tendon during isometric contraction.

The purpose of this study was investigate tendon displacement patterns in non-surgically treated patients 14 months after acute Achilles tendon rupture (ATR) and to classify patients into groups based on their Achilles tendon (AT) displacement patterns. Twenty patients were tested. Sagittal images of AT were acquired using B-mode ultrasonography during ramp contractions at a torque level corresponding to 30% of the maximal isometric plantarflexion torque of the uninjured limb. A speckle tracking algorithm was used to track proximal-distal movement of the tendon tissue at 6 antero-posterior locations. Two-way repeated measures ANOVA for peak tendon displacement was performed. K-means clustering was used to classify patients according to AT displacement patterns. The difference in peak relative displacement across locations was larger in the uninjured (1.29 ± 0.87 mm) than the injured limb (0.69 ± 0.68 mm), with a mean difference (95% CI) of 0.60 mm (0.14-1.05 mm, P < .001) between limbs. For the uninjured limb, cluster analysis formed 3 groups, while 2 groups were formed for the injured limb. The three distinct patterns of AT displacement during isometric plantarflexion in the uninjured limb may arise from subject-specific anatomical variations of AT sub-tendons, while the two patterns in the injured limb may reflect differential recovery after ATR with non-surgical treatment. Subject-specific tendon characteristics are a vital determinant of stress distribution across the tendon. Changes in stress distribution may lead to variation in the location and magnitude of peak displacement within the free AT. Quantifying internal tendon displacement patterns after ATR provides new insights into AT recovery.