Achilles tendon (AT) plays a crucial role during walking. In cerebral palsy (CP), altered neuromuscular development appears to affect AT morphology and stiffness, disrupting muscle-tendon interaction and gait. This study quantified differences in static AT morphology and passive mechanical properties in children and young adults with CP and examined whether these properties are related to AT function during walking. Twelve young individuals with CP and 12 typically developing (TD) peers underwent three-dimensional freehand ultrasonography to obtain AT datasets from which cross-sectional area (CSA) and lengths were extracted. Shear wave elastography was used to estimate the shear modulus of the free AT. Three-dimensional gait analysis was synchronized with ultrasound during overground walking, enabling estimation of AT length changes during stance along with lower-limb kinematics and kinetics. Free AT was 86.7±34.6mm longer in CP than TD (p=0.015) and remained longer after normalization to tibia length (p=0.025). No significant differences were observed in medial gastrocnemius AT length and CSA. Within CP, CSA was correlated negatively with walking speed (r=-0.66, p=0.026) and positively correlated with AT length changes during walking (r=0.79, p=0.002). This study shows that the free AT length is longer in CP than in TD peers, with no differences in AT CSA. Only limited structure-function associations were observed, suggesting altered involvement of AT stretch-recoil during walking in CP. These explorative results require further evaluation with larger samples and homogenous CP groups.

A longer Achilles tendon (AT) moment arm (MA) relative to the foot length requires less muscle force for a given plantarflexion moment, thereby lowering mechanical load on the tendon. We examined whether the AT and foot MA lengths in healthy (N=28) differ from height and body mass matched individuals with AT tendinopathy (N=28) and rupture (N=29). We hypothesized that a longer AT MA has a protective effect on tendon loading with the patient groups having smaller MA compared to asymptomatic individuals. MAs were assessed using 2-D image-based method. AT MA was defined as the shortest distance from the centre line of action of the AT to the line between malleoli. Ratio of ankle lever was calculated by dividing AT by Foot MAs. AT MA was longer in healthy than either the tendinopathy (mean difference 3.86mm, p=0.02) or rupture group (5.41mm, p<0.001). Foot MA was not statistically different between the groups (p=0.06). Ratio of ankle lever differed between groups with the healthy group showing higher ratio compared to both the tendinopathy group (0.04, p=0.001), and the rupture group (0.06, p<0.001). AT and Foot MAs correlated with body mass and height, whereas the ratio of ankle lever did not. A longer AT relative to foot MA length may improve the tendon's safety factor by reducing mechanical stress. This ratio may serve as an accessible intrinsic risk factor for AT injuries, even when assessed only using simple 2-D anatomical measures.

Predicting Achilles tendon and patellofemoral joint forces during running with consumer-grade wearable sensor data.

Intratendinous sliding, that is, nonuniform motions between the superficial and deep layers of the Achilles tendon, is reduced in individuals with Achilles tendinopathy compared with healthy controls during isometric contractions. Previous work has shown that intratendinous sliding can be increased by performing isometric contractions with a horizontally outward-rotated ("toes-out") foot position. The purpose of this study was to compare intratendinous sliding between healthy individuals and patients with Achilles tendinopathy during dynamic exercises, and to determine the effect of a toes-out foot position. Forty participants (20 healthy and 20 Achilles tendinopathy) performed dynamic exercises, including bilateral heel rise/drop (sitting and standing), unilateral heel rise/drop (knee extended and bent), and squat. Exercises were performed in a neutral and toes-out foot position, with ultrasound images captured using an external probeholder. Intratendinous sliding (mm) was estimated via a speckle tracking algorithm as the difference between displacement of the superficial and deep layers of the Achilles tendon. Main effects of group, foot position, and exercise were found, indicating that Achilles tendinopathy patients have reduced intratendinous sliding, that intratendinous sliding can be increased in a toes-out foot position, and that some exercises induce more intratendinous sliding than others. These findings support intratendinous sliding as a marker of tendon health and suggest that foot positioning may be a simple way to enhance sliding. Given the poor rehabilitation outcomes for Achilles tendinopathy patients, implementing an external foot position during rehabilitation protocols could offer a low-cost and easy-to-implement method to improve rehabilitation success rates.

Surface EMG analysis of tibialis anterior and gastrocnemius activity under different loading positions.

Ultrasound-guided percutaneous needle fenestration (UPNF) and percutaneous needle tenotomy (UPNT) are minimally invasive procedures commonly used to treat chronic tendinopathies. However, these techniques can be painful, potentially limiting patient tolerance, satisfaction, and procedural feasibility. Although local anesthetics (LAs) provide analgesia, their potential inhibitory effects on tenocyte activity and the efficacy of orthobiologics raise concerns regarding their impact on tendon healing. The objectives of this study is to propose a practical, anatomy-based approach for the use of ultrasound-guided peripheral nerve blocks (USG-PNBs) as a strategy to reduce pain and improve patient comfort during UPNF and UPNT, with or without orthobiologic adjuncts. We reviewed commonly affected anatomical sites in chronic tendinopathies and identified corresponding peripheral nerve targets that can be reliably and safely blocked under ultrasound guidance. For each condition, we outline appropriate nerve block techniques, anatomical landmarks, and recommended patient positioning to optimize procedural analgesia. A set of targeted USG-PNBs was defined for commonly treated tendinopathies, including supraspinatus tendinopathy, lateral and medial epicondylitis, gluteus medius and/or minimus tendinopathy, patellar tendinopathy, Achilles tendinopathy, and plantar fasciopathy. Ultrasound-guided peripheral nerve blocks represent a practical and effective approach to manage pain during percutaneous procedures for chronic tendinopathies. By reducing procedural discomfort and avoiding the potential drawbacks of peritendinous LAs, these techniques may enhance patient tolerance, procedural success, and overall clinical outcomes.

Mid-term functional outcomes of arthroscopy-assisted lower trapezius transfer using doubled peroneus longus tendon.

Effect of heel drop static stretching on triceps surae stiffness through shear wave elastography.

Psychological and functional assessment of Achilles tendon ruptures and their return to sports.

Artistic gymnastics is a complex and challenging sport. The specific demands of gymnastics place athletes at unique risk of injuries to the spine, as well as upper and lower extremities. Changes to the rules and scoring system since the 2004 Olympics have encouraged athletes to perform more challenging skills, adding to the risk of injury. Single-sport specialization occurs at a young age among competitive gymnasts, introducing an increased risk of overuse injuries. Common injuries include spondylolysis, medial-sided elbow injuries, gymnast's wrist, ligamentous injuries of the knee, and Achilles tendon ruptures. It is important to understand these injury patterns to properly prevent, treat, and safely return these athletes to play.

Quantitative MRI using ultrashort echo time (UTE)-T2* mapping is sensitive to collagen-bound water and tendon microstructure, enabling noninvasive assessment of tendon integrity and laxity. However, the extent to which UTE-T2* measures reflect changes in tendon tension, and their repeatability, remain incompletely understood. We evaluated the sensitivity of mono- and bi-exponential UTE-T2* measures of the Achilles tendon to changes in tendon tension induced by ankle positioning and assessed the test-retest repeatability of these metrics across repeated scan sessions. In this study, healthy adult volunteers underwent UTE-MRI of the Achilles tendon at two scan sessions, spaced 1 week apart, with the ankle positioned in dorsiflexion (higher tendon tension) and plantarflexion (lower tendon tension). Mono-exponential T2* (T2*mono) and bi-exponential parameters (T2*short, T2*long, and short-component fraction ρshort) were quantified. We performed a two-way repeated-measures ANOVA to assess the main effects of ankle position and scan session, and their interaction. Repeatability was evaluated using root mean square error (RMSE), coefficient of variation (CV%), and Bland-Altman analysis. We observed that short-component T2* metrics demonstrated significant sensitivity to tendon tension. A main effect of ankle position was observed for T2*mono (p < 0.001) and T2*short (p = 0.02), with lower values in dorsiflexion compared with plantarflexion. No significant effect of scan session or ankle position × scan session interactions were observed. T2*long and ρshort showed no significant dependence on position or scan session, suggesting that bulk hydration and relative water-compartment contributions remained stable across loading conditions. Dorsiflexion demonstrated lower RMSE and CV% across metrics than plantar flexion, indicating improved repeatability under passive tendon tension. UTE-T2* relaxometry of the Achilles tendon is repeatable and sensitive to changes in tendon tension. Short T2* measures may provide quantitative imaging markers related to tendon mechanical integrity and laxity, while highlighting the importance of standardized tendon tension for longitudinal quantitative tendon MRI.

Rerupture rate after ACL reconstruction in adolescent female soccer players: a case series.

Incomplete recovery with persistent muscle weakness is frequently observed following Achilles tendon rupture. The mechanisms for this weakness remain unclear, but tendon elongation has been suggested as a contributing factor. The aim of this study was to compare tendon and muscle morphology in high- and low-functioning patients more than 2 years after non-surgical treatment of a total Achilles tendon rupture. Forty-six patients underwent screening, including a standardized heel-rise work test on both legs. Based on this test, a heel-rise index (HRI) for total muscle work, categorized 29 patients into a low- (HRI < 33%) or high-functioning (HRI > 67%) group. Both groups underwent bilateral magnetic resonance imaging to assess tendon and muscle morphology, and the main variable was tendon elongation. High-functioning patients were on average 13 years younger than the low-functioning patients (p < 0.001). Free tendon length was longer on the injured side in both groups, 3.59 and 5.19 cm in the high- and low-functioning group (p = 0.053). Tendon cross-sectional area was significantly larger in the high-functioning group compared to the low-functioning group (383% vs. 256% after normalization to the uninjured side, p = 0.005). The soleus muscle had notable differences between the groups, as low-functioning patients had a smaller mediolateral diameter (p = 0.002), a more pronounced muscle length difference (p = 0.009) and a higher atrophy grading. Additionally, there were significant correlations between age, HRI and tendon size. Free tendon length after rupture may play a role in muscle weakness. However, tendon elongation does not necessarily lead to low function, as it was also evident in the high-functioning group. These findings may be important, as they suggest that tendon elongation is not the sole determinant of functional outcome and that other factors may contribute to muscle performance after rupture. Further research is needed on the role of age in muscle function following Achilles tendon ruptures. Level III.

Fixed cavovarus foot deformity is characterised by a plantar-flexed first ray, hindfoot varus, and abnormal plantar loading, often resulting in pain, instability, and gait dysfunction. The surgical correction we performed involved a deformity-driven approach to address the structural apex and associated components. Evidence linking this multilevel correction strategy to objective biomechanical improvement remains limited. This prospective case series evaluated outcomes following a uniform deformity-driven multilevel surgical correction protocol for fixed cavovarus deformity consisting of combined Cole midfoot osteotomy, Dwyer calcaneal osteotomy, and open Achilles tendon lengthening performed in all cases. Thirty-two relatively young skeletally mature patients (37 feet), predominantly with neuromuscular etiology, were included and followed for a minimum of 18 months. Primary outcome measures were patient-reported functional outcomes assessed using the Foot and Ankle Ability Measure Activities of Daily Living subscale (FAAM-ADL), radiologic alignment parameters on standardised weight-bearing radiographs, and objective gait and plantar pressure metrics. Secondary outcomes included postoperative complications. The Foot and Ankle Disability Index (FADI) was analysed as a secondary patient-reported outcome. FAAM-ADL scores improved significantly from a preoperative mean of 45.2 to 77.2 at 18 months (P < .001). All radiologic parameters demonstrated significant correction, including Meary angle, calcaneal pitch angle, lateral talocalcaneal angle, anteroposterior talometatarsal angle, and talonavicular coverage angle (all P < .001). Gait analysis demonstrated a significant increase in comfortable walking speed (1.0 to 1.4 m/s, P < .001) and redistribution of plantar loading, with reduced lateral column pressures and increased midfoot contact area (all P < .001). The secondary FADI score also improved significantly over time (P < .001). Complications included transient postoperative pain during the first 12 months, 1 superficial wound infection, and 1 case of deformity recurrence. In this prospective case series, deformity-driven multilevel surgical correction for fixed cavovarus deformity with a midfoot apex was associated with significant improvements in patient-reported function, radiologic alignment, and objective biomechanical parameters. These findings support the role of apex-targeted multilevel correction in appropriately selected patients with rigid midfoot-driven cavovarus deformity.

This study investigated the ankle-to-knee and knee-to-ankle joint energy transfer via the biarticular gastrocnemii muscles during unpredictable and adapted drop-like gait perturbations to understand how biarticular mechanisms of the gastrocnemii contribute to the mechanical work performed by the Achilles tendon (AT) force at the ankle joint. This was done by measuring AT elongation and quantifying AT force as an indicator of triceps surae muscle forces, as well as the body kinematics and electromyographic activity of the soleus, gastrocnemius medialis and gastrocnemius lateralis muscles, in 17 participants. Biarticular mechanisms contributed significantly to both the negative and positive mechanical work performed by the AT force at the ankle joint during both types of drop-like perturbations, constituting 17% to 26% of this mechanical work. In particular, during the initial stance phase of unpredictable, drop-like perturbations, a significant proportion of energy (26% of the negative mechanical work done at the ankle joint) was transferred from the ankle to the knee joint via the biarticular gastrocnemii muscles. More importantly, the rate of this energy transfer was elevated during the unpredictable perturbations, when beneficial stability control mechanisms based on prediction are unavailable, compared with adapted ones. Finally, our findings imply that elastic tissues contribute significantly to managing drop-like perturbations, including energy storage and recoil in the AT and potential for elastic energy exchange in the vasti tendons during the energy transfer phases. These findings could inform the design of prevention treatments and bioengineering approaches, especially for improving stability control in uneven terrain.

To explore the surgical technique and effectiveness of limited bone and soft tissue surgery combined with Ilizarov technique in the treatment of adolescents severe cerebral palsy with flattened valgus foot and lower leg external rotation deformity. A retrospective analysis was conducted on 12 patients with severe cerebral palsy with flattened valgus foot and external rotation deformity of the lower leg, totaling 16 feet, admitted between January 2022 and January 2025. There were 5 males with 7 feet and 7 females with 9 feet, the age ranged from 12 to 18 years, with an average of 15 years. There were 10 cases on the left foot, 6 cases on the right foot, and 4 cases on both feet. The preoperative external rotation angle of the lower leg ranged from 20° to 35°, with an average of 26°. The preoperative visual analogue scale (VAS) score was 4.9±0.9, the American Orthopaedic Foot & Ankle Society (AOFAS) score was 68.7±12.0, the calcaneal tilt angle was (12.69±1.78)°, and the hindfoot angle was (18.69±3.55)°. Patients with bilateral lower leg deformities underwent surgery in two phases, with an interval of 3-6 months between surgeries. Select soft tissue surgery (Achilles tendon elongation, release or transposition of joint capsule and ligaments) and bone surgery (joint fusion, calcaneal osteotomy, medial wedge osteotomy, etc.) combined with tibiofibular internal rotation osteotomy and Ilizarov external fixation were selected according to the patient's condition. At 1 week after operation, the external fixators of the lower leg and ankle were slowly adjusted, and the deformities that were not completely solved in the three-dimensional correction operation were corrected. Postoperative pain relief and functional recovery were evaluated by VAS and AOFAS scores, and the improvement of foot deformity was evaluated by calcaneal tilt angle and hindfoot angle on radiographic data, and the postoperative effctiveness was evaluated according to the International Clubfoot Study Group (ICFSG). At 2 weeks after operation, the foot deformity of the patient was basically adjusted. All patients were followed up 6-36 months, with an average of 18 months. The incisions healed by first intention without nerve injury, infection, or other complications. At last follow-up, the patients recovered satisfactorily, the osteotomy sites healed, and the external rotation of the lower leg was corrected. The VAS score was 1.2±0.1 and AOFAS score was 86.7±6.8, which were significantly different from those before operation ( P<0.05). The calcaneal tilt angle was (18.38±1.15)° and the hindfoot angle was (10.06±2.93)°, which were significantly different from those before operation ( P<0.05). According to the ICFSG scoring standard, 13 feet were excellent and 3 feet were good, and the excellent and good rate was 100%. The combination of bone and soft tissue limited surgery and Ilizarov technique is a safe, minimally invasive, and effective method for treating severe cerebral palsy in adolescents with flattened valgus foot and external rotation deformity of the lower leg. It conforms to biological principles and follows the concept of natural bone reconstruction.

Obesity profoundly impairs musculotendinous structure and function, but the extent to which these alterations can be reversed remains unclear. This study compared the effects of aerobic exercise (EX) and caloric restriction (CR) on the recovery of muscle-tendon structural integrity, contractile performance and passive mechanical properties in high-fat diet-induced obese mice. Male C57BL/6J mice were fed a high-fat diet for 28weeks and remained on this diet during a subsequent 6week intervention of either treadmill training (OBEX, 5daysweek-1 at 45-65% ) or 30% caloric restriction (OBCR), whereas controls received standard chow with (CNEX) or without exercise (CN). Muscle [soleus, extensor digitorum longus (EDL)] and Achilles tendon mechanical properties, morphology and composition were assessed alongside circulating and tissue-specific remodelling markers. OB had higher circulating transforming growth factor beta 1, periostin and advanced glycation end products, accompanied by higher muscle and tendon fibrosis. These molecular and structural alterations coincided with slower contraction-relaxation kinetics, lower specific force and increased tissue viscosity. EX but not CR increased tissue energy storage capacity. OBCR but not OBEX had lower muscle AGEs and muscle collagen fraction than OB. In CR, this was associated with significant improvements in muscle-specific force. However, tendon properties remained largely unaffected following CR. In summary, a 6week CR decreased body mass, normalized glucose tolerance, reduced fibrosis and improved muscle contractility. By contrast, EX enhanced aerobic capacity and modestly improved tissue mechanical behaviour, but had limited effects on body mass, fibrosis, and muscle contractile function. These findings indicate that caloric restriction and exercise induce distinct, only partially overlapping adaptations, highlighting differential contributions of metabolic and mechanical pathways to the recovery of muscle-tendon function in obesity. KEY POINTS: Obesity is known to induce skeletal muscle dysfunction, but it is unclear to what extent this can be reversed by lifestyle interventions such as exercise or reduced food intake. Using a mouse model of diet induced obesity, we compared aerobic exercise with caloric restriction to assess recovery of muscle-tendon structure and function. Obesity caused excess connective tissue to accumulate in muscles and tendons, leading to lower specific force, slower contraction and relaxation, and a stiffer and more viscous muscle-tendon complex. Compared to exercise, caloric restriction more effectively restored muscle specific force and tissue composition than exercise, whereas tendon recovery remained limited. Caloric restriction and exercise elicit distinct, partly overlapping adaptations, suggesting that metabolic and mechanical pathways differentially drive muscle-tendon recovery following diet-induced obesity.

Achilles tendon rupture impairs the functional performance of the triceps surae muscle-tendon unit. However, long-term effects of different rehabilitation programs on these impairments remain unclear. This study evaluated the long-term effects of early rehabilitation versus cast immobilization after Achilles tendon repair. We also examined whether the uninjured side could serve as a reference for the "healthy" side. Males with previous Achilles tendon rupture (n=20) and a group of healthy male controls (CTR; n=10) participated. Achilles tendon rupture participants included a short-term physical therapy group (STPT; n=10) and a plaster cast group (PC; n=10). Triceps surae morphology of the injured leg and ankle functionality of both injured groups was compared with that of the uninjured leg and with that of CTR legs. No between-group differences were found in the patient-reported outcomes. The injured side presented lower heel rise height, plantar flexors strength, gastrocnemius medialis thickness, calf volume, and shorter fascicle length than CTR. On the injured side, the STPT preserved ankle range of motion and showed greater plantar flexion and total range of motion than the PC. We employed a computational model that demonstrated that tendon elongation was the main determinant of heel rise height deficit. The uninjured side presented lower heel rise height than the CTR group. Despite favorable patient-reported outcomes, long-term structural and functional deficits persist after Achilles tendon rupture, regardless of rehabilitation approach. Findings suggest that the rehabilitation programs used did not fully restore muscle-tendon function and highlight limitations of using the uninjured side as a control.

Artificial muscles, owing to their lightweight nature, mechanical compliance and the ability to emulate biological muscle actuation, demonstrate immense potential in the field of bionic intelligent robotics. However, existing ionic electrochemical actuators generally exhibit pronounced frequency dependence and unstable actuation outputs under variable-frequency operation, which severely limit their ability to simulate scenarios requiring stable performance across varying frequencies. Herein, we report a zinc tetraphenylporphyrin (Zn-TPP)/1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) electrolyte membrane, in which the anionic TPP2- framework effectively anchors EMIm+ cations. This effect restricts cation migration under applied electric fields and thereby stabilizes the charge distribution within the electrolyte membrane. Benefiting from this mechanism, the actuator achieves an outstanding 99.97% displacement retention over a broad frequency range of 0.1-5 Hz at 3 V. In contrast, a conventional EMImBF4/PVDF-HFP-based electrochemical actuator exhibits a displacement retention of only 25% at 5 Hz. By comparing devices with three different TPP2--containing electrolyte membranes, we confirm a positive correlation between the electrostatic potential of TPP2- and actuator displacement retention. A higher electrostatic potential enables stable operation over a broader frequency range, whereas a lower electrostatic potential reduces stability but yields larger bending displacement, thereby allowing a tunable balance between stability and displacement amplitude to meet diverse application needs. In addition, the actuator maintains stable performance over a relative humidity range of 40-70%, ensuring reliable operation in biofluid-like environments. Notably, the actuator mimics the contraction behavior of the human Achilles tendon and maintains stable, repeatable responses under varied rhythmic conditions, highlighting its potential for next-generation soft robotics.

As scientific publishing has shifted to digital platforms, two primary article-publishing modalities have emerged: open access and closed access. Open access is freely accessible with an article processing charge (APC) paid by authors, whereas closed access lies behind paywalls, with low to no APC for authors. As the academic community increasingly relies on digital dissemination, it is critical to evaluate how these models influence research visibility and impact. This study compared open versus closed access randomized control trials (RCTs) across five prevalent orthopaedic conditions by analyzing attention scores, social media metrics, readership, and citations. The study hypothesis was that open access publications would have higher attention and readership, whereas closed access articles would yield more citations. A PubMed search was conducted in May 2025 to identify RCTs on rotator cuff tears, carpal tunnel syndrome, hip fractures, anterior cruciate ligament tears, and Achilles tendon ruptures. Altmetric Attention Scores, X mentions, Facebook mentions, news mentions, Mendeley readers, and Dimensions citations were collected for each article using the Altmetric Explorer database. A negative binomial regression, adjusted for time since publication, was used to compare metrics between open and closed access publications. Of 1,223 articles studied, 53.8% of the articles were open access and 46.2% were closed access. Open access articles had significantly higher Altmetric Attention Scores (44.1 ± 197 vs 17.2 ± 52.0), X mentions (32.2 ± 27.1 vs 17.4 ± 38.4), Facebook mentions (1.2 ± 4.3 vs 1 ± 2.5), news mentions (4.1 ± 25.2 vs 1.0 ± 7.2), number of Mendeley readers (136.6 ± 127.9 vs 113.4 ± 108), and, notably, number of Dimensions citations (36.8 ± 88.9 vs 30.1 ± 45.6) compared with closed access articles ( P < 0.05). Contrary to our initial hypothesis, open access articles had higher attention metrics and citation numbers when compared with closed access publications. These findings suggest that open access publishing not only enhances visibility and engagement but also may increase academic impact across multiple orthopaedic subspecialties.