Achilles Tendon Stiffness in the Etiology of Sever Disease: A Shear Wave Elastography Study.

BACKGROUND: Sever disease is one of the most common causes of heel pain in growing children and adolescents. There is no consensus about etiology of Sever disease. METHODS: The study comprised 41 participants aged 8 to 13 years who visited the orthopedic outpatient clinic: 17 patients with Sever disease and 24 asymptomatic children. The middle third segment of the body of the Achilles tendon and the calcaneal insertion zone were separately assessed. Five measuring points for the quantitative value of each point were randomly selected. The color scale used in the Young's modulus shows the lowest values in blue and the highest values in red. The mean values were used for the statistical analysis. RESULTS: Less elasticity was detected at the insertional site for the control group (4.02 kPa versus 3.65 kPa), the situation was reversed in the body of the Achilles tendon and the elasticity of the study group was less than that of the control group (241.0 kPa versus 260.5 kPa). However, no statistically significant difference was found between the groups. CONCLUSIONS: In conclusion, no difference was found in Achilles tendon elasticity between patients with Sever disease and healthy individuals in both the tendon body and the calcaneal insertionof the tendon. Achilles tendon elasticity has not been found to play a role in the etiology of Sever disease.

Comparative analysis of patellar tendon, achilles tendon and plantar fascia structure in indoor and outdoor football players: a novel cross-sectional pilot study.

Different sport modalities were associate with tendon adaptation or even tendon disturbances, such as volleyball, soccer or basketball. Purpose: the aim of the present study was to determine de difference between indoor and outdoor football players on patellar tendon (PT), Achilles tendon (AT), plantar fascia (FP) and Hoffa's fat pad thickness assessed with ultrasound imaging (USI). A cross-sectional study was developed with a total sample of 30 soccer players divided in two groups: outdoor group (n = 15) and indoor group (n = 15). The thickness of PT, AT, PF and Hoffa's fat pad has been assessed with USI. Hoffa's fat pad reported significant differences for the left side between groups (P = 0.026). The rest of variables did not show any significant difference (P < 0.05). The ultrasonography assessment of the thickness of the PT, AT and PF did not show differences between outdoor and indoor football players. Hoffa's fat pad resulted showed a significant decrease for outdoor soccer players with respect futsal players. Thus, it can be considered that the load stimuli received in both soccer players were not enough to produce structural adaptations in PT, AT and PF tissues.

Applications of medical imaging in the monitoring and rehabilitation of physical conditions in athletes

By means of imaging, athletic injuries can be more comprehensively and accurately screened and functionally evaluated, so as to guide the treatment and rehabilitation after athletic injuries in a more targeted manner. Chronic injuries and tendinopathies of the Achilles tendon occur mostly in the middle and lower part of the Achilles tendon, which is the most frequent site of Achilles tendon rupture, and Achilles tendon rupture will lead to a huge impact on athletic injurie performance, and even end their athletic career prematurely. Ultrasound imaging technology can clearly and completely show the tissue and its continuity changes, which is helpful for the setting of rehabilitation program and the judgment of prognosis. The Siemens VTIQ provides quantitative information on the viscoelastic properties of the tissue, allowing an accurate and safe assessment of the elastic properties of the Achilles tendon. In this paper, the third generation ARFI technique, VTIQ technology, was applied to study the Achilles tendon of healthy youth and professional athletes to obtain the effects of exercise on the Achilles tendon and to provide medical imaging support for monitoring the health of the Achilles tendon in athletes and for the post-injury rehabilitation process (AU)

Acute fracture of an extensively ossified segment of the Achilles tendon.

Extensive tendon ossification is thought to be rare and is hypothesised to occur due to cell-mediated tissue remodelling. Literature outlining risk factors for the development of an ossified segment, and then a consequent fracture is limited to case reports and case series. A woman in her fifties with a background of several autoimmune disorders presented to a sports and exercise medicine clinic with posterior ankle pain following a bout of brisk walking a month prior. CT and MRI imaging demonstrated a fractured extensively ossified segment of the corresponding Achilles tendon. Conservative treatment was trialled for six months, however, was unsuccessful. Surgical excision of the calcified fragment and flexor hallucis longus tendon transfer were suggested as a potential solution. This case is compared with and builds on current literature surrounding pathophysiology and optimal treatment of extensively ossified segments of the Achilles tendon.

Evaluation of Achilles Tendon Stiffness as Measured by Shear Wave Elastography in Female College Athletes Compared With Nonathletes.

BACKGROUND: We sought to utilize a noninvasive technology to assess the effects of activity on Achilles tendon stiffness and define baseline Achilles tendon stiffness in female college athletes compared with nonathletes using tendon shear wave velocity as a marker for tendon stiffness. HYPOTHESIS: Training status and exercise may affect Achilles tendon stiffness. LEVEL OF EVIDENCE: Level 4. METHODS: A total of 32 college-age female athletes were prospectively enrolled (n = 17 varsity athletes and n = 15 nonathletes). Demographic characteristics, activity level, and previous injuries were recorded. Sonographic shear wave elastography (SWE) was used to assess Achilles tendon shear wave velocity bilaterally for all subjects, both at baseline and after 2 minutes of exercise. Student t tests were used to compare the mean elastography measurements between participants stratified by athlete status and pre/postexercise stimulus. Analysis of variance (ANOVA) was used to compare the mean proximal, middle, and distal Achilles tendon elastography measurements. RESULTS: As seen by a greater mean shear wave velocity (8.60 ± 1.58 m/s vs 8.25 ± 1.89 m/s; P = 0.02), athletes had stiffer tendons than nonathletes. Exercise stimulus decreased average tendon shear wave velocity (8.57 ± 1.74 m/s vs 8.28 ± 1.72 m/s; P = 0.05). Tendon shear wave velocity was greatest proximally and least distally with significant differences between each region (P < 0.001). In addition, there was a significant 2-way interaction between weekly training status and foot dominance (P = 0.01). Post hoc analysis showed that this result was due to differences in tendon shear wave velocity between the dominant and nondominant lower extremity in nonathletes (7.73 ± 2.00 m/s vs 8.76 ± 1.62 m/s; P < 0.001). CONCLUSION: Female varsity collegiate athletes have higher baseline Achilles tendon stiffness as measured by SWE compared with nonathletes. Mean tendon stiffness varies based on Achilles measurement location. SWE is a quick, cost-effective, and noninvasive imaging modality that can be used to evaluate tendon stiffness and elasticity. CLINICAL RELEVANCE: SWE is an efficient and noninvasive imaging modality that can evaluate dynamic tendon stiffness and elasticity. SWE may be helpful to assess injuries in female college athletes and may play a role in risk stratification or clinical follow-up. In theory, SWE could be used to identify athletes with increased elasticity as a marker for potential risk for rupture in this population.

Effects of a 12-week gait retraining program on the Achilles tendon adaptation of habitually shod runners.

PURPOSE: This study investigated the effects of a 12-week gait retraining program on the morphological and mechanical properties of the Achilles tendon (AT) during running on the basis of real-time dynamic ultrasound imaging. METHODS: A total of 30 male recreational runners who were used to wearing cushioned shoes with a rearfoot strike (RFS) pattern were recruited. They were randomized into a retraining group (RG, n = 15) and a control group (CG, n = 15). The RG group was asked to run in five-fingered minimalist shoes with a forefoot strike (FFS) pattern, and the CG group was asked to keep their strike pattern. Three training sessions were performed per week. All the participants in RG uploaded running tracks obtained through a mobile application (.jpg) after each session for training supervision. The ground reaction force, kinematics, and kinetics of the ankle joint at 10 km/h were collected using an instrumented split-belt treadmill and a motion capture system. The morphological (length and cross-sectional area) and mechanical characteristics (force, stress, strain, etc.) of AT in vivo were recorded and calculated with a synchronous ultrasonic imaging instrument before and after the intervention. Repeated two-way ANOVA was used to compare the aforementioned parameters. RESULTS: A total of 28 participants completed the training. The strike angle of RG after training was significantly smaller than that before training and significantly smaller than that of CG after training (F (1, 13) = 23.068, p < 0.001, partial η2 = 0.640). The length (F (1, 13) = 10.086, p = 0.007, partial η2 = 0.437) and CSA (F (1, 13) = 7.475, p = 0.017, partial η2 = 0.365) of AT in RG increased after training. A significant main effect for time was observed for the time-to-peak AT force (F (1, 13) = 5.225, p = 0.040, partial η2 = 0.287), average (F (1, 13) = 7.228, p = 0.019, partial η2 = 0.357), and peak AT loading rate (F (1, 13) = 11.687, p = 0.005, partial η2 = 0.473). CONCLUSION: Preliminary evidence indicated that a 12-week gait retraining program could exert a beneficial effect on AT. 57% (8/14) runners in RG shifted from RFS to FFS pattern. Although not all runners were categorized as FFS pattern after the intervention, their foot strike angle was reduced. Retraining primarily positively promoted AT morphological properties (i.e., CSA and length) to strengthen AT capability for mechanical loading.

Where is Your Pain? Achilles Tendinopathy Pain Location on Loading Is Different to Palpation, Imaging and Recall Location.

OBJECTIVE: To describe and compare pain maps reported during Achilles tendon loading exercises with recall pain location, in people with pain on palpation in their Achilles tendon and tendon pathology on imaging. DESIGN: Cross-sectional analysis of baseline RCT. METHOD: Participants were recruited from a larger Achilles tendinopathy clinical trial. Inclusion criteria were at least 2-month self-reported history of Achilles tendinopathy, midtendon palpation pain, and pathology on ultrasound tissue characterization. Participants were asked to identify their Achilles tendon pain location on a pain map with 8 prespecified locations while at rest prior to loading (recall pain), and subsequently during tendon loading exercises (loading pain). Participants could select multiple locations or select "other" if the locations did not represent their pain. RESULTS: Ninety-three participants were included (93% of participants from a clinical trial). The locations of pain on loading were diverse; all 8 pain locations (and an "other" option) were represented within this sample. Twenty-five percent of participants did not report pain with loading (n = 23 of 93). Of the 70 participants with loading pain, recall pain location differed to loading pain location in 40% (n = 28 of 70) of the participants. CONCLUSION: Palpation pain location, recall pain location, or location of pathology on imaging were not valid proxies for load-related pain in the Achilles tendon. How different pain locations respond to treatment is unknown. Some pathologies (eg, plantaris) have clear pain locations (eg, medial tendon), and assessing pain location may assist differential diagnosis. J Orthop Sports Phys Ther 2024;54(1):1-9. Epub 7 December 2023. doi:10.2519/jospt.2023.12131.

Low-Intensity Pulsed Ultrasound Promotes the Repair of Achilles Tendinopathy by Downregulating the JAK/STAT Signaling Pathway in Rabbits.

Tendinopathy is a complex tendon injury or pathology outcome, potentially leading to permanent impairment. Low-intensity pulsed ultrasound (LIPUS) is emerging as a treatment modality for tendon disorders. However, the optimal treatment duration and its effect on tendons remain unclear. This study aims to investigate the efficacy of LIPUS in treating injured tendons, delineate the appropriate treatment duration, and elucidate the underlying treatment mechanisms through animal experiments. Ninety-six three-month-old New Zealand white rabbits were divided into normal control (NC) and model groups. The model group received Prostaglandin E2 (PGE2) injections to induce Achilles tendinopathy. They were then divided into model control (MC) and LIPUS treatment (LT) groups. LT received LIPUS intervention with a 1-MHz frequency, a pulse repetition frequency (PRF) of 1 kHz, and spatial average temporal average sound intensity ( [Formula: see text]) of 100 mW/cm2. MC underwent a sham ultrasound, and NC received no treatment. Assessments on 1, 4, 7, 14, and 28 days after LT included shear wave elastography (SWE), mechanical testing, histologic evaluation, ribonucleic acid sequencing (RNA-seq), polymerase chain reaction (PCR), and western blot (WB) analysis. SWE results showed that the shear modulus in the LT group was significantly higher than that in the MC group after LT for seven days. Histological results demonstrated improved tendon tissue alignment and fibroblast distribution after LT. Molecular analyses suggested that LIPUS may downregulate the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway and regulate inflammatory and matrix-related factors. We concluded that LT enhanced injured tendon elasticity and accelerated Achilles tendon healing. The study highlighted the JAK/STAT signaling pathway as a potential therapeutic target for LT of Achilles tendinopathy, guiding future research.

ISB clinical biomechanics award winner 2023: Medial gastrocnemius muscle and Achilles tendon interplay during gait in cerebral palsy.

BACKGROUND: The interplay between the medial gastrocnemius muscle and the Achilles tendon is crucial for efficient walking. In cerebral palsy, muscle and tendon remodelling alters the role of contractile and elastic components. The aim was to investigate the length changes of medial gastrocnemius belly and fascicles, and Achilles tendon to understand their interplay to gait propulsion in individuals with cerebral palsy. METHODS: Twelve young individuals with cerebral palsy and 12 typically developed peers were assessed during multiple gait cycles using 3D gait analysis combined with a portable ultrasound device. By mapping ultrasound image locations into the shank reference frame, the medial gastrocnemius belly, fascicle, and Achilles tendon lengths were estimated throughout the gait cycle. Participants with cerebral palsy were classified into equinus and non-equinus groups based on their sagittal ankle kinematics. FINDINGS: In typically developed participants, the Achilles tendon undertook most of the muscle-tendon unit lengthening during stance, whereas in individuals with cerebral palsy, this lengthening was shared between the medial gastrocnemius belly and Achilles tendon, which was more evident in the equinus group. The lengthening behaviour of the medial gastrocnemius fascicles resembled that of the Achilles tendon in cerebral palsy. INTERPRETATION: The findings revealed similar length changes of the medial gastrocnemius fascicles and Achilles tendon, highlighting the enhanced role of the muscle in absorbing energy during stance in cerebral palsy. These results, together with the current knowledge of increased intramuscular stiffness, suggest the exploitation of intramuscular passive forces for such energy absorption.

Diagnostic Imaging for Achilles Tendinopathy: Unnecessary Scans? Valuable Insights? Multidisciplinary Clinician-Scientists Present a Nuanced View.

SYNOPSIS: Clinical practice guidelines for Achilles tendinopathy do not recommend imaging to inform diagnosis. However, there is considerable variation in how imaging is used, particularly in research and sports. Early imaging risks that people who see the images presume that what they "see" as pathology is the primary cause of pain; patients might end up receiving invasive treatments on the basis of the image when rehabilitation may suffice. On the other hand, imaging can help rule out Achilles tendinopathy and identify differential diagnoses. As more rehabilitation clinicians are direct access practitioners and take on expanded roles as primary health practitioners, ultrasound imaging might serve as a valuable point-of-care tool for diagnosis, identifying conditions that warrant referral and managing conditions like Achilles tendinopathy. We argue that the value of ultrasound imaging to diagnose tendinopathy outweighs the potential limitations. J Orthop Sports Phys Ther 2024;54(1):1-4. Epub 16 November 2023. doi:10.2519/jospt.2023.12255.

Achilles tendon and triceps surae muscle properties in athletes.

PURPOSE: The aim of this study was to investigate internal Achilles tendon (AT) displacement, AT shear wave velocity (SWV), and triceps surae (TS) muscle shear modulus in athletes. METHODS: Internal AT displacement was assessed using ultrasound during isometric contraction. Shear wave elastography was used to assess AT SWV (m × s-1) at rest and TS muscle shear modulus (kPa) during passive ankle dorsiflexion. RESULTS: A total of 131 athletes participated in this study. Athletes who had not exercised within two days had greater AT non-uniformity and mean anterior tendon displacement, and lower SWV at the proximal AT measurement site (mean difference [95% CI]: 1.8 mm [0.6-2.9], p = 0.003; 1.6 mm [0.2-2.9], p = 0.021; - 0.9 m × s-1 [- 1.6 to - 0.2], p = 0.014, respectively). Male basketball players had a lower mean AT displacement compared to gymnasts (- 3.7 mm [- 6.9 to - 0.5], p = 0.042), with the difference localised in the anterior half of the tendon (- 5.1 mm [- 9.0 to - 1.1], p = 0.022). Male gymnasts had a smaller absolute difference in medial gastrocnemius-minus-soleus shear modulus than basketball players (59.6 kPa [29.0-90.2], p < 0.001) and track and field athletes (52.7 kPa [19.2-86.3], p = 0.004). Intraclass correlation coefficients of measurements ranged from 0.720 to 0.937 for internal AT displacement, from 0.696 to 0.936 for AT SWE, and from 0.570 to 0.890 for TS muscles. CONCLUSION: This study provides a reliability assessment of muscle and tendon SWV. The relative differences in passive TS muscle shear modulus suggest sport-specific adaptation. Importantly, in healthy individuals, lower AT displacement after exercise may reflect the time required for tendon recovery.

Micro- and nanostructure specific X-ray tomography reveals less matrix formation and altered collagen organization following reduced loading during Achilles tendon healing.

Recovery of the collagen structure following Achilles tendon rupture is poor, resulting in a high risk for re-ruptures. The loading environment during healing affects the mechanical properties of the tendon, but the relation between loading regime and healing outcome remains unclear. This is partially due to our limited understanding regarding the effects of loading on the micro- and nanostructure of the healing tissue. We addressed this through a combination of synchrotron phase-contrast X-ray microtomography and small-angle X-ray scattering tensor tomography (SASTT) to visualize the 3D organization of microscale fibers and nanoscale fibrils, respectively. The effect of in vivo loading on these structures was characterized in early healing of rat Achilles tendons by comparing full activity with immobilization. Unloading resulted in structural changes that can explain the reported impaired mechanical performance. In particular, unloading led to slower tissue regeneration and maturation, with less and more disorganized collagen, as well as an increased presence of adipose tissue. This study provides the first application of SASTT on soft musculoskeletal tissues and clearly demonstrates its potential to investigate a variety of other collagenous tissues. STATEMENT OF SIGNIFICANCE: Currently our understanding of the mechanobiological effects on the recovery of the structural hierarchical organization of injured Achilles tendons is limited. We provide insight into how loading affects the healing process by using a cutting-edge approach to for the first time characterize the 3D micro- and nanostructure of the regenerating collagen. We uncovered that, during early healing, unloading results in a delayed and more disorganized regeneration of both fibers (microscale) and fibrils (nanoscale), as well as increased presence of adipose tissue. The results set the ground for the development of further specialized protocols for tendon recovery.

Combined Assessment of 2-D Ultrasound and Real-Time Shear Wave Elastography of Low-Intensity Pulsed Ultrasound Therapy Efficacy in Rabbits with Achilles Tendinopathy.

OBJECTIVE: Low-intensity pulsed ultrasound (LIPUS) has been gradually used to treat Achilles tendinopathy. However, there are limited non-invasive and efficient instruments for monitoring LIPUS efficacy in Achilles tendinopathy. The purpose of this study was to assess the therapeutic effectiveness of LIPUS after Achilles tendinopathy by 2-D ultrasound and real-time shear wave elastography (SWE). METHODS: Ninety New Zealand white rabbits were divided into control, sham and LIPUS groups after tendinopathy modeling. On days 1, 4, 7, 14 and 28, the Achilles tendon thickness and SWE Young's modulus on the long axis were measured. The tissues of the Achilles tendon were then evaluated histologically. RESULTS: The mean SWE values increased while the average thickness and histologic scores decreased, especially in the LIPUS group (9.5% and 80.7% on day 28, respectively). The SWE values in the LIPUS group were significantly lower than those in the control group on day 1 (121.0 kPa vs. 177.6 kPa) and peaked on day 7 (173.7 kPa, p < 0.001). By day 28, the SWE value had approached that of the control (191.2 kPa vs. 192.4 kPa), and had been significantly higher than that in the sham group since day 7. SWE values and histologic scores were correlated (r = -0.792, p < 0.01). The average thickness decreased in the three groups but did not differ significantly. CONCLUSION: Two-dimensional ultrasound is beneficial to the diagnosis of Achilles tendinopathy. SWE could quantify changes in Achilles tendon stiffness non-invasively during LIPUS treatment, enabling the study of early Achilles tendon healing after LIPUS treatment.

Measuring Ultrasonographic Thickness of the Achilles Tendon Insertion Is Less Reliable Than the Midportion in Healthy Tendons and Patients With Tendinopathy.

INTRODUCTION: Ultrasound is the preferred imaging method in the diagnostic process of Achilles tendinopathy (AT). Ultrasound tissue characterization (UTC) is a frequently used, standardized and valid method to assess tendon geometry in AT patients. It is unknown whether UTC is reliable for measuring Achilles tendon thickness. The aim of the study was to assess intra- and inter-rater reliability of Achilles tendon thickness measurements using UTC in both asymptomatic individuals and patients with AT, and to evaluate if the reliability of thickness measurements differs between the midportion and insertional area. METHODS: Exactly 50 patients with AT and 50 asymptomatic individuals were included. Using the conventional US and standardized UTC procedure maximum thickness was measured in the midportion and insertion region. To determine inter- and intra-rater reliabilities, the intraclass correlation coefficient (ICC) was used. RESULTS: The ICC values for inter- and intra-rater reliability were classified as "excellent," for the AT group (0.93 [95% CI: 0.88-0.96] and 0.95 [0.92-0.97]) and asymptomatic participants (0.91 [0.87-0.94] and 0.94 [0.92-0.96]). The reliability of measuring tendon thickness in the midportion region was "excellent," with both inter-rater (0.97 [0.95-0.98]) and intra-rater (0.98 [0.96-0.99]) ICC values indicating high levels of agreement. In the insertional region, ICC values for inter-rater (0.79 [0.69-0.87]) and intra-rater (0.89 [0.84-0.93]) reliability were "moderate to good." CONCLUSION: We showed excellent reliability for measuring the US thickness of the midportion and good reliability of measuring the insertional region in patients with AT. Significantly lower ICCs were observed for the reliability of thickness measurements in the insertional region when compared with the midportion.

Achilles tendon and enthesis assessment using ultrashort echo time magnetic resonance imaging (UTE-MRI) T1 and magnetization transfer (MT) modeling in psoriatic arthritis.

The purpose of this study is to investigate the use of ultrashort echo time (UTE) magnetic resonance imaging (MRI) techniques (T1 and magnetization transfer [MT] modeling) for imaging of the Achilles tendons and entheses in patients with psoriatic arthritis (PsA) compared with asymptomatic volunteers. The heels of twenty-six PsA patients (age 59 ± 15 years, 41% female) and twenty-seven asymptomatic volunteers (age 33 ± 11 years, 47% female) were scanned in the sagittal plane with UTE-T1 and UTE-MT modeling sequences on a 3-T clinical scanner. UTE-T1 and macromolecular proton fraction (MMF; the main outcome of MT modeling) were calculated in the tensile portions of the Achilles tendon and at the enthesis (close to the calcaneus bone). Mann-Whitney-U tests were used to examine statistically significant differences between the two cohorts. UTE-T1 in the entheses was significantly higher for the PsA group compared with the asymptomatic group (967 ± 145 vs. 872 ± 133 ms, p < 0.01). UTE-T1 in the tendons was also significantly higher for the PsA group (950 ± 145 vs. 850 ± 138 ms, p < 0.01). MMF in the entheses was significantly lower in the PsA group compared with the asymptomatic group (15% ± 3% vs. 18% ± 3%, p < 0.01). MMF in the tendons was also significantly lower in the PsA group compared with the asymptomatic group (17% ± 4% vs. 20% ± 5%, p < 0.01). Percentage differences in MMF between the asymptomatic and PsA groups (-16.6% and -15.0% for the enthesis and tendon, respectively) were higher than the T1 differences (10.8% and 11.7% for the enthesis and tendon, respectively). The results suggest higher T1 and lower MMF in the Achilles tendons and entheses in PsA patients compared with the asymptomatic group. This study highlights the potential of UTE-T1 and UTE-MT modeling for quantitative evaluation of entheses and tendons in PsA patients.

An automated method for tendon image segmentation on ultrasound using grey-level co-occurrence matrix features and hidden Gaussian Markov random fields.

BACKGROUND: Despite knowledge of qualitative changes that occur on ultrasound in tendinopathy, there is currently no objective and reliable means to quantify the severity or prognosis of tendinopathy on ultrasound. OBJECTIVE: The primary objective of this study is to produce a quantitative and automated means of inferring potential structural changes in tendinopathy by developing and implementing an algorithm which performs a texture based segmentation of tendon ultrasound (US) images. METHOD: A model-based segmentation approach is used which combines Gaussian mixture models, Markov random field theory and grey-level co-occurrence (GLCM) features. The algorithm is trained and tested on 49 longitudinal B-mode ultrasound images of the Achilles tendons which are labelled as tendinopathic (24) or healthy (25). Hyperparameters are tuned, using a training set of 25 images, to optimise a decision tree based classification of the images from texture class proportions. We segment and classify the remaining test images using the decision tree. RESULTS: Our approach successfully detects a difference in the texture profiles of tendinopathic and healthy tendons, with 22/24 of the test images accurately classified based on a simple texture proportion cut-off threshold. Results for the tendinopathic images are also collated to gain insight into the topology of structural changes that occur with tendinopathy. It is evident that distinct textures, which are predominantly present in tendinopathic tendons, appear most commonly near the transverse boundary of the tendon, though there was a large variability among diseased tendons. CONCLUSION: The GLCM based segmentation of tendons under ultrasound resulted in distinct segmentations between healthy and tendinopathic tendons and provides a potential tool to objectively quantify damage in tendinopathy.

Clinical and Ultrasonographic Characteristics of the Achilles Tendon in Hemodialysis Patients.

Background and Objectives: The early recognition of tendon alterations in chronic hemodialysis (HD) patients, an awareness of the factors that influence the condition, and active intervention have considerable clinical relevance. The aim of this study was to investigate the musculoskeletal ultrasound (MSUS) features of the Achilles tendon in chronic HD patients and determine the factors associated with tendon abnormalities. Materials and Methods: This study was conducted on 46 HD patients and 24 sex- and age-matched controls. All participants were evaluated clinically for any signs of Achilles tendon abnormalities. Then, the Achilles tendon was scanned bilaterally using MSUS. Results: Among the 92 Achilles tendons in the HD patients, there was tenderness and swelling of only two (2.2%). Regarding MSUS features, there were statistically significant higher thicknesses in the proximal end (p < 0.001), midpoint (p < 0.001), and distal end (p < 0.001) of the Achilles tendons in the HD patients when compared with the healthy controls. Tendinosis was found in 12 (13%) of the HD patients' Achilles tendons, which was statistically significant in comparison to the healthy controls (p = 0.008). There were statistically significant higher scores of structural abnormalities (p = 0.005), bone erosions (p = 0.017), and calcifications (p = 0.015) in the HD patients when compared to the healthy controls. According to the results of a univariate regression analysis, age and male gender were predictive for US abnormalities in HD patients (p = 0.002 and 0.025, respectively). Conclusions: The Achilles tendon in subjects on chronic HD showed frequent US abnormalities. These abnormalities in HD patients appear to be more related to age and gender and may be asymptomatic.

Does the ultrasound imaging predict lower limb tendinopathy in athletes: a systematic review.

BACKGROUND: To conduct a systematic review looking into the possibility of US imaging to anticipate and identify future patellar or Achilles tendinopathy symptoms. METHODS: The studies that were taken into consideration for this review were prospective studies that employed baseline US imaging of the patellar OR Achilles tendons in asymptomatic patients and follow-up measures of pain and/or function. Two impartial reviewers evaluated the study's quality using the Critical Appraisal Skills Programme instrument. RESULTS: Participants in the included studies in this review came from various sports. The systematic review revealed a link between baseline tendon abnormalities in the US and a higher chance of developing both patellar and Achilles tendinopathy as well as their future occurrence. Nine of the included studies examined the patellar tendon alone, eight the patellar and Achilles tendon together, and four the Achilles tendon exclusively. For both tendons, US administration is done in a largely consistent manner. The tendon abnormalities of tendon thickness, hypoechogenicity and vascularity at baseline were associated with an increased risk of both Achilles and patellar tendinopathy. CONCLUSIONS: This systematic review shows that abnormal tendon structures seen by US in asymptomatic persons can predict the development of tendinopathy.

Fibroblast Activation Protein-Targeted PET/CT With Al18F-NODA-FAPI-04 for In Vivo Imaging of Tendon Healing in Rat Achilles Tendon Injury Models.

BACKGROUND: Fibroblast activation protein (FAP) has shown high expression in inflammatory responses and fibrosis. HYPOTHESIS: We speculated that FAP could serve as a diagnostic and monitoring target in the tendon healing process. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 72 Sprague-Dawley rats were randomly divided into a tendon crush group and a half-partial tendon laceration group. Four rats in each group were injected with radiotracers weekly for 4 weeks after surgery, with aluminum fluoride-labeled 1,4,7-triazacyclononane-N,N',N″-triacetic acid-conjugated FAP inhibitor (Al18F-NODA-FAPI-04) administered on the first day of each week and 18F-fludeoxyglucose (18F-FDG) on the next day. Small animal positron emission tomography (PET) imaging was performed, and tendon tissue was collected for pathology and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis each week after surgery. RESULTS: One week after surgery, both radiotracers showed signal concentration at the lesion site, which was the highest radioactive uptake observed during 4 weeks postoperatively, consistent with the severity of the lesion. Consistent trends were observed for inflammatory cytokines during qRT-PCR analysis. Additionally, Al18F-NODA-FAPI-04 PET exhibited a more precise lesion pattern, attributed to its high specificity for naive fibroblasts when referring to histological findings. Over time, the uptake of both radiotracers at the injury site gradually decreased, with 18F-FDG experiencing a more rapid decrease than Al18F-NODA-FAPI-04. In the fourth week after surgery, the maximum standardized uptake values of Al18F-NODA-FAPI-04 in the injured lesion almost reverted to the baseline levels, indicating a substantial decrease in naive fibroblasts and inflammatory cells and a reduction in inflammation and fibrosis, especially compared with the first week. Corresponding trends were also revealed in pathological and qRT-PCR results. CONCLUSION: Our findings suggest that inflammation is a prominent feature during the early stage of tendon injury. Al18F-NODA-FAPI-04 PET allows accurate localization and provides detailed morphological imaging, enabling continuous monitoring of the healing progress and assessment of injury severity.