Biomechanics of the ankle

Change of joint line convergence angle and other coronal alignments after total hip arthroplasty

BACKGROUND

The purpose of this study was to determine the unloading effect of total hip arthroplasty (THA) on the ipsilateral knee joint through the joint line convergence angle (JLCA) change and determine the changes in other coronal radiographic parameters after THA, and evaluate the sensitivity of JLCA.

PATIENTS AND METHODS

We retrospectively assessed 70 patients who underwent unilateral THA. Hip parameters such as neck shaft angle (NSA), neck length, and femoral offset and coronal alignment parameters of the lower extremity such as hip-knee-ankle angle (HKA), femur length, mechanical lateral distal femoral angle (mLDFA), JLCA, medial proximal tibial angle (MPTA), lateral distal tibial angle (LDTA), and plafond talus angle (PTA) were measured in the operative and non-operative sides. We compared all hip and coronal alignment parameters between before and 1 year after THA, and the amount of standardized changes (Δ) between all hip and coronal alignment parameters on the operative side, respectively.

RESULTS

All mean hip and coronal alignment parameters on the operative side changed significantly 1-year after THA; however, those on the non-operative side did not. On the operative side, mean JLCA and PTA changed in the direction of closing the joint lateral space, from 1.81° and 0.47° to 1.22° and 0.11°, respectively (p<0.001 and 0.046, respectively). Mean NSA, HKA, and mLDFA changed in the valgus direction, from 129.39°, 2.62°, and 86.69° to 133.54°, 1.53°, and 85.91°, respectively (p<0.001). Mean femoral offset, neck length, and femur length increased from 36.45mm, 47.83mm, and 429.20mm to 39.85mm, 55.06mm, and 436.33mm, respectively (p<0.001). Mean MPTA and LDTA increased from 85.43° and 87.50° to 86.73° and 90.38, respectively (p<0.001). JLCA was more vulnerable to change than HKA, femur length, mLDFA, MPTA, and PTA (p<0.05).

DISCUSSION

JLCA change on the operative side was more sensitive than changes of other coronal alignments after THA. According to the cohort, THA might have an unloading effect on the medial compartment of the knee joint.

LEVEL OF EVIDENCE

IV; retrospective case-control and cohort studies.

Influence of whole-body vibration and drop jump on the range of motion in the ankle joint and running parameters-A randomized crossover study

BACKGROUND AND PURPOSE

Warm-up (WU) is a commonly practiced technique aimed at preparing athletes for physical activity. Although coaches and athletes consider WU essential, there is still an ongoing debate about its effectiveness. This might be due to the fact that WU procedures often rely on experiences rather than scientific research. During WU, athletes may pursue intermediate goals such as ensuring proper ranges of motion in joints, which seem crucial particularly for runners' ankle joints. Hence, the aim of this study was to evaluate influence of whole-body vibration (WBV), drop jump (DJ), and a combination of both (WBV + DJ) in terms of ankle dorsiflexion and running parameters among recreational runners.

METHODS

Sixteen runners performed as a WU: five sets of 30 s calf raises without WBV (CTRL), five sets of 30 s calf raises during WBV, five sets of six DJ, five sets of 30 s calf raises during WBV followed by 6 DJ. Range of motion (ROM) of the ankle joint was measured in a prone position using an inclinometer for the soleus and gastrocnemius muscles, separately. Measurements were conducted before and after WU, and after a 3000 m run.

RESULTS

There was no interaction for time and WU for left (p = 0.926) and right (p = 0.738) soleus muscle as well as for left (p = 0.748) and right (p = 0.197) gastrocnemius muscles. No difference (p = 0.914) for the running time was found.

DISCUSSION

WBV, drop jumps, or a combination of both did not affect ankle dorsiflexion and running time.

Effect of Obesity on Short- and Long-Term Complications After Ankle Fracture Fixation

OBJECTIVES

This study evaluated the relationship between obesity and postoperative complications in patients undergoing ankle open reduction internal fixation (ORIF).

METHODS

DESIGN

Retrospective cohort study.

SETTING

PearlDiver-Mariner All-Payor Database.

PATIENT SELECTION CRITERIA

Patients who underwent ankle ORIF from 2010 to 2021 and had a minimum of 2 years of follow-up were identified using Current Procedural Terminology, ICD-9, and ICD-10 codes.

OUTCOME MEASURES AND OUTCOMES

Patients were stratified by body mass index into nonobese, obese, morbidly obese, and super-obese groups. Complication rates, including 90-day readmissions, infection, and post-traumatic osteoarthritis, were compared between obesity groups. Patients were additionally compared with a 1:1 matched analysis that controlled for demographics and comorbidities.

RESULTS

A total of 160,415 patients undergoing ankle ORIF from 2010 to 2021 were identified. The cohort consisted mostly of females (64.8%) and the average age was 52.5 (SD 18.4) years. There were higher rates of 90-day readmissions, UTIs, DVT/PE, pneumonia, superficial infections, and acute kidney injuries in patients with increasing levels of obesity (P < 0.001). There were increased odds of nonunion and post-traumatic arthritis in the matched analysis at 2 years in the obesity group [OR: 2.36, 95% confidence interval (CI): 1.68-3.31, P < 0.001; OR: 2.18, 95% CI: 1.77-2.68, P < 0.001, respectively].

CONCLUSIONS

Postoperative medical complication rates in patients undergoing ankle ORIF, including infection, are higher in obese patients, even in the 1:1 matched analysis that controlled for demographic and comorbidity factors. Rates of nonunion and post-traumatic arthritis were higher in obese patients, as well. As such, it is important for surgeons to provide appropriate education regarding the risks after ankle ORIF in patients with obesity.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparative finite element analysis of contact and stress distribution in tibiotalar articular cartilage: Healthy versus varus ankles

Background

The distribution of forces within the ankle joint plays a crucial role in joint health and longevity. Loading disorders affecting the ankle joint can have significant detrimental effects on daily life and activity levels. This study aimed to enhance our understanding of the mechanical behavior of tibiotalar joint articular cartilages in the presence of varus deformity using finite element analysis (FEA) applied to patient-specific models.

Methods

Two personalized ankle models, one healthy and another with varus deformity, were created based on CT scan images. Four static loading scenarios were simulated at the center of pressure (COP), coupled to the hindfoot complex. The contact area, contact pressure, and von Mises stress were computed for each cartilage.

Results

It was found that the peak contact pressure increased by 54% in the ankle with varus deformity compared to the healthy ankle model. Furthermore, stress concentrations moving medially were observed, particularly beneath the medial malleolus, with an average peak contact pressure of 3.5 MPa and 4.7 MPa at the tibial and talar articular cartilages, respectively.

Conclusion

Varus deformities in the ankle region have been consistently linked to elevated contact pressure, increasing the risk of thinning, degeneration, and eventual onset of osteoarthritis (OA), emphasizing the need for prompt interventions aimed at mitigating complications.

Joint synergy and muscle activity in the motion of the ankle-foot complex

The movement of the ankle-foot complex joints is coupled as a result of various physiological and physical constraints. This study introduces a novel approach to the analysis of joint synergies and their physiological basis by focusing on joint rotational directions and the types of muscle contractions. We developed a biomimetic model of the ankle-foot complex with seven degrees of freedom, considering the skeletal configuration and physiological axis directions. Motion capture experiments were conducted with eight participants performing dorsiflexion and plantarflexion in open-chain states, as well as various walking tasks in closed-chain states, across different ground inclinations (±10, ±5, 0 deg) and walking speeds (3 and 4 km h-1). Hierarchical cluster analysis identified joint synergy clusters and motion primitives, revealing that in open-chain movements, plantarflexion of the ankle, tarsometatarsal and metatarsophalangeal joints exhibited synergy with the inversion of the remaining joints in the complex; meanwhile, dorsiflexion was aligned with eversion. During closed-chain movements, the synergies grouping was exchanged in the subtalar, talonavicular and metatarsophalangeal joints. Further analysis showed that in open-chain movements, synergy patterns influenced by multi-joint muscles crossing oblique joint axes contribute to foot motion. In closed-chain movements, these changes in synergistic patterns enhance the propulsion of the center of mass towards the contralateral leg and improve foot arch compliance, facilitating human motion. Our work enhances the understanding of the physiological mechanisms underlying synergistic motion within the ankle-foot complex.

Efficacy of hinged and carbon fiber ankle-foot orthoses in children with unilateral spastic cerebral palsy and drop-foot gait pattern

BACKGROUND

In children with unilateral spastic cerebral palsy (USCP), ankle-foot orthoses (AFOs) are widely used to correct common gait deviations such as a drop-foot pattern. Most studies on this topic have investigated specific time points while omitting other parts of the gait cycle.

OBJECTIVES

This study investigated the separate effects of prefabricated carbon fiber AFOs and custom-made hinged AFOs compared with barefoot walking in children with USCP with a drop-foot gait pattern using statistical parametric mapping.

STUDY DESIGN

Retrospective, cross-sectional, repeated measures study.

METHODS

Twenty ambulatory children (9.9 ± 2.5 years) with USCP and a drop-foot gait pattern were included. Kinematics, kinetics, and spatiotemporal parameters assessed during 3-dimensional gait analysis were compared between barefoot and AFO walking. Statistical parametric mapping was used to compare joint angles and moment waveforms. Kinematics, kinetics and spatiotemporal parameters assessed during 3-dimensional gait analysis were compared between barefoot and AFO walking for each AFO type but not between the 2 AFO types.

RESULTS

Compared with barefoot walking, there was a steeper sole angle at initial contact, corresponding to a heel strike pattern, and an increased ankle dorsiflexion in swing with the use of both AFOs. The ankle plantar flexion moment during loading response increased. Ankle power generation during pre-swing decreased in the carbon fiber AFO group when walking with AFOs.

CONCLUSIONS

Both AFOs were beneficial for improving a drop-foot gait pattern in these small patient groups and can, therefore, be recommended to treat this gait deviation in patients with unilateral cerebral palsy. However, the reduction in ankle power generation during push-off and additional goals targeted by AFOs, such as correction of structural or flexible foot deformities, should be considered for prescription.

Intraday Variation of Ankle Dorsiflexion in Short-Track Speed Skaters

PURPOSE

Optimal ankle dorsiflexion range of motion plays a vital role in attaining the essential crouched posture necessary for excelling in speed skating. The purpose of this study was to determine how the ankle dorsiflexion angle evolves throughout a day of training and to identify the factors that influence this angle.

METHODS

Thirty short-track speed skaters, from 2 teams, participated in this study. The maximum ankle dorsiflexion angle was obtained in a lunge position facing a wall, using a digital inclinometer. All measures were obtained 3 times per side, 6 times per day, on 2 training days separated by at least a week. We conducted multiple tests to study the impact of repetition, day, side, team level, sex, and moment on the ankle dorsiflexion angle.

RESULTS

The 3 times repeated measures and the 2 days of training did not have a significant influence on the results. There was a statistically significant difference between the first time point of the day and the 5 other time points for both ankles. Moreover, the influence of sex and team level was not statistically significant.

CONCLUSIONS

The results indicate that there are significant changes in ankle dorsiflexion range of motion but only after the first warm-up of the day. Such findings could enable team staff to enhance athletes' precompetition preparation and tailor ankle mobility training regimens more effectively.

Efficacy of Maitland Mobilization and Myofascial Release as Preoperative Care in Ankle Arthritis With Severe Equinus Deformity: A Rare Case Report

Advanced post-traumatic ankle osteoarthritis (PTAO) is a severe condition that affects less than one percent of the population, with rare incidence. It accounts for less than 5% of all osteoarthritis (OA) cases. Physiotherapy enhances functionality by strengthening the dynamic stabilizers of the ankle, such as the calf, soleus, tibialis anterior, and peroneal muscles, and by improving proprioception, which aids in balance and coordination. As OA progresses, individuals may experience early losses in their ability to perform everyday activities and job tasks. Occupational therapy and cardiovascular exercises are crucial for conserving energy while walking and improving posture at work. This case report involves a 39-year-old male who presented to the hospital with pain, swelling, difficulty walking, and an equinus deformity. After diagnosing him with ankle arthritis, the orthopedic specialist recommended an X-ray. Medication and physical therapy were administered to educate and rehabilitate the patient, aiming to improve pain, range of motion (ROM), strength, and walking capacity. A four-week treatment plan, along with medication, resulted in significant improvements in pain reduction, ROM, strength, and walking ability. This case report also underscores the importance of focusing on preoperative care to ensure that post-surgery, the hip and knee ranges are normal, and the patient experiences less difficulty walking. Future studies are needed to explore this condition further and to evaluate the effectiveness of ultrasound therapy in such cases, as it was not effective in reducing pain in this instance.

MRI Evaluation of Traumatic and Non-traumatic Pathologies of the Ankle Joint and Hindfoot: A Single-Center Observational Study

Background Pathologies affecting the ankle joint and hindfoot can present with a variety of clinical symptoms and etiologies, necessitating accurate diagnostic tools for effective management. Magnetic resonance imaging (MRI) is a valuable imaging modality for assessing these pathologies, providing detailed visualization of bone, joint, tendon, and other soft tissue abnormalities. Objectives To evaluate MRI findings in a diverse cohort of 105 participants with pathologies affecting the ankle joint and hindfoot, focusing on the prevalence and types of bone, joint, tendon, and soft tissue abnormalities. Materials and methods A single-center observational descriptive study was conducted at Dr. D. Y. Patil Medical College and Hospital and Research Centre, Pune, India, over a period from August 2022 to July 2024, involving 105 participants (54.3% male, 45.7% female) with a mean age of 39.04 years. MRI scans were analyzed to assess the prevalence of bone, joint, tendon, and soft tissue pathologies. Clinical profiles, symptom duration, and etiological classifications were documented. Results Analysis of the results obtained from 105 (N = 105) study participants revealed that pain (94.3%, or 99 cases) was the most common symptom, followed by restricted movement (86.7%, or 91 cases), trauma history (75.2%, or 79 cases), and swelling (73.3%, or 77 cases). Traumatic causes (76.2%, or 80 cases) predominated, while inflammatory (48.3%, or 14 cases) and infective (34.5%, or 10 cases) causes were also significant. MRI findings showed marrow edema in 41.9%, or 44 cases, subchondral cysts in 22.9% (24 cases), fractures in 17.1% (18 cases), and erosions in 10.5% of participants (11 cases). Joint involvement was most frequent in the tibiotalar (76.2%, or 80 cases) and subtalar joints (58.1%, or 61 cases). Tendon pathologies included peritendonitis (55.2%, or 58 cases) and tendinosis (23.8%, or 25 cases), with the Achilles tendon being the most frequently affected (39%, or 41 cases). Ligament injuries were predominantly sprains (46.7%, or 49 cases), with less frequent partial (18.1%, or 19 cases) and complete tears (7.6%, or eight cases). Soft tissue findings included subcutaneous edema (76.2%, or 80 cases) and bursitis (24.8%, or 26 cases). Among the study participants who presented with non-traumatic pathologies, inflammatory pathologies (48.3%, or 14 cases) were the most common, followed by infective (34.5%, or 10 cases) and neoplastic (17.2%, or five cases) pathologies. Conclusion MRI effectively identifies a wide range of pathologies in the ankle and hindfoot, with marrow edema, joint effusion, and tendon pathologies being prevalent. The study underscores the utility of MRI in diagnosing and assessing various conditions in the ankle joint complex and highlights the need for accurate imaging to guide treatment decisions. Future research should focus on correlating MRI findings with clinical outcomes to enhance diagnostic accuracy and management strategies.

Effects of Rehabilitative Exercise and Neuromuscular Electrical Stimulation on Muscle Morphology and Dynamic Balance in Individuals with Chronic Ankle Instability

Background and Objectives: Muscle atrophy caused by chronic ankle instability (CAI) can incur muscle weakness, altered movement patterns, and increased risk of injury. Previous studies have investigated the effects of rehabilitative exercises and neuromuscular electrical stimulation (NMES) on characteristics in CAI individuals, but few studies have examined their effects on foot and ankle muscle morphology. This study aimed to determine the effects of rehabilitative exercises and NMES on muscle morphology and dynamic balance in individuals with CAI. Materials and Methods: Participants with CAI (n = 47) were randomly divided into control (CG), rehabilitative exercise (REG), NMES (NG), and rehabilitative exercise and NMES combined (RNG) groups. The six-week intervention program consisting of rehabilitative exercises and NMES was applied to groups excluding CG. Muscle morphology and dynamic balance were evaluated using a portable wireless diagnostic ultrasound device and dynamic balance tests. For statistical analysis, an effect size with 95% confidence interval was calculated to assess mean differences according to intervention. Results: After six weeks, significant increases in morphology and dynamic balance were observed for all muscles except flexor hallucis longus (p > 0.05) in the intervention groups except for CG. However, no significant changes were observed in the CG (p > 0.05). Conclusions: These findings suggest that intervention programs may help prevent muscle atrophy and improve balance in CAI individuals.

Lower leg muscle activation during the ebbets foot drills

Lateral ankle sprains (LAS) often lead to chronic ankle instability (CAI). The Ebbets foot drills were created to strengthen the lower leg muscles and reduce the risk of LAS. The current study aimed to explore the activation of the lower leg muscles during the Ebbets foot drills. Twenty-two (22) college students without LAS participated in the study. Surface electromyography (sEMG) of the tibialis anterior (TA), tibialis posterior (TP), and peroneus longus (PL) was collected during each of the Ebbets foot drills and a normal walking trial. The sEMG mean root mean square (RMS) was calculated for each walking and Ebbets foot drill trial duration. The mean RMS was higher during the Ebbets foot drills compared to normal walking for all muscles. The TA sEMG mean RMS was greater (4.0-68.3%, P = 0.001-0.023) during all the Ebbets foot drills than during the walking trial. The TP had greater mean RMS during the toe-in (50.4%, P < 0.001), toe-out (55.0%, P < 0.001), and backward walking (47.3%, P < 0.001) drills, than during the walking trial. The PL had greater mean RMS during all Ebbets foot drills (19.4-53.7%, P < 0.001) except for the heel walking and inversion drills. Ebbets foot drills higher muscle activity than regular walking, suggesting that the Ebbets foot drills could aid in the strengthening of the TA, TP, and PL muscles. These results build evidence on Ebbets' theory and indicate that these drills may be used to rehabilitate LAS and CAI.

Estimation of minimum foot clearance using a single foot-mounted inertial sensor and personalized foot geometry scan

The real-world measurement of minimum foot clearance (mFC) during the swing phase of gait is critical in efforts to understand and reduce the risk of trip-and-fall incidents in populations with gait impairments. Past research has focused on measuring clearance of a single point on a person's foot, typically the toe-however, this may overestimate mFC and may even be the wrong region of the foot in cases of gait impairments or interventions. In this work, we present a novel method to reconstruct the swing-phase trajectory of an arbitrary number of points on a person's shoe and estimate the instantaneous height and location of whole-foot mFC. This is achieved using a single foot-mounted inertial sensor and personalized shoe geometry scan, assuming a rigid-body IMU-shoe system. This combination allows collection and analysis using out-of-lab tests, potentially including clinical environments. Validation of single marker location using the proposed method vs. motion capture showed height errors with bias less than 0.05 mm, and 95% confidence interval of - 8.18 to + 8.09 mm. The method is demonstrated in an example data set comparing different interventions for foot drop, and it shows clear differences among no intervention, functional electrical stimulation, and ankle-foot orthosis conditions. This method offers researchers and clinicians a rich understanding of a person's gait by providing objective 3D foot kinematics and allowing a unique opportunity to view the regions of the foot where minimum clearance occurs. This information can contribute to a more informed recommendation of specific interventions or assistive technology than is currently possible in standard clinical practice.

Activated nitinol compression staples are associated with favorable biomechanical properties for talonavicular arthrodesis

Background

Nitinol compression staple use in foot and ankle arthrodesis procedures, including for the talonavicular joint, has gained acceptance. A previous study provided evidence for using nitinol compression staples in talonavicular arthrodesis (TNA) based on functional biomechanical testing comparisons to "gold standard" lag screw fixation. This study aimed to further compare the functional biomechanical properties of nitinol compression staple fixation to lag screw fixation for arthrodesis of the talonavicular joint. Body-temperature incubation and ankle inversion and eversion loading sequences were added to previously reported biomechanical testing.

Methods

Robotic testing was performed on cadaveric feet (n = 10; 5 matched pairs) after TNA using either two nitinol compression staples or two fully threaded lag screws. TNA method was randomized, alternating between matched-pairs of left and right feet. After surgical stabilization, specimens were incubated at 38 °C for 24 h to simulate the initial postoperative period in a patient. After plantarflexion and dorsiflexion testing, the specimens underwent inversion and eversion testing, cycling from 20° inversion to 10° eversion for 10 cycles. Displacements were tracked using optical tracking markers. Significant (p < 0.05) differences between staple versus screw fixation cohorts were determined using paired t-Tests.

Results

All specimens completed testing with none experiencing failure at the TNF. No statistically significant differences in functional biomechanical testing properties were noted between nitinol compression staple fixation and lag screw fixation for TNA.

Conclusion

The study findings provide additional support for nitinol compression staple fixation as an option for talonavicular arthrodesis fixation. Taken together, the results of functional biomechanical testing studies have provided sufficient evidence for initiation of a prospective clinical outcomes study using nitinol compression staples for talonavicular arthrodesis fixation at our institution.

Achilles Tendon Loading during Running Estimated Via Shear Wave Tensiometry: A Step Toward Wearable Kinetic Analysis

PURPOSE

Understanding muscle-tendon forces (e.g., triceps surae and Achilles tendon) during locomotion may aid in the assessment of human performance, injury risk, and rehabilitation progress. Shear wave tensiometry is a noninvasive technique for assessing in vivo tendon forces that has been recently adapted to a wearable technology. However, previous laboratory-based and outdoor tensiometry studies have not evaluated running. This study was undertaken to assess the capacity for shear wave tensiometry to produce valid measures of Achilles tendon loading during running at a range of speeds.

METHODS

Participants walked (1.34 m·s -1 ) and ran (2.68, 3.35, and 4.47 m·s -1 ) on an instrumented treadmill while shear wave tensiometers recorded Achilles tendon wave speeds simultaneously with whole-body kinematic and ground reaction force data. A simple isometric task allowed for the participant-specific conversion of Achilles tendon wave speeds to forces. Achilles tendon forces were compared with ankle torque measures obtained independently via inverse dynamics analyses. Differences in Achilles tendon wave speed, Achilles tendon force, and ankle torque across walking and running speeds were analyzed with linear mixed-effects models.

RESULTS

Achilles tendon wave speed, Achilles tendon force, and ankle torque exhibited similar temporal patterns across the stance phase of walking and running. Significant monotonic increases in peak Achilles tendon wave speed (56.0-83.8 m·s -1 ), Achilles tendon force (44.0-98.7 N·kg -1 ), and ankle torque (1.72-3.68 N·m·(kg -1 )) were observed with increasing locomotion speed (1.34-4.47 m·s -1 ). Tensiometry estimates of peak Achilles tendon force during running (8.2-10.1 body weights) were within the range of those estimated previously via indirect methods.

CONCLUSIONS

These results set the stage for using tensiometry to evaluate Achilles tendon loading during unobstructed athletic movements, such as running, performed in the field.

Ankle Instability: Facts and Myths to Protect Your Cartilage Repairing

The majority of patients with an osteochondral lesion of the talus (OLT) report a history of trauma. Therefore, it is important to assess for concomitant ankle instability when dealing with patients with a symptomatic OLT. The History; Alignment; Ligaments; Others "(HALO)" approach can be a helpful tool in the evaluation of patients with an OLT. If conservative treatment fails, surgery may be indicated. Although there is a lack of comparative studies investigating the effect of stabilization procedures on cartilage repair, we believe that addressing instability is a key factor in improving patient outcome.

Assistance force-line of exosuit affects ankle multidimensional motion: a theoretical and experimental study

BACKGROUND

The talocrural joint and the subtalar joint are the two major joints of the ankle-joint complex. The position and direction of the exosuit force line relative to these two joint axes can influence ankle motion. We aimed to understand the effects of different force-lines on ankle multidimensional motion.

METHODS

In this article, three assistance force line schemes for ankle exosuits were proposed: perpendicular to the talocrural joint axis (PT), intersecting with the subtalar joint axis (IS), and parallel to the triceps surae (PTS). A theoretical model was proposed to calculate the exosuit's assistance moment. Seven participants completed four experimental tests of ankle plantarflexion, including three passive motions assisted by the PT, PTS and IS schemes, and one active motion without exosuit assistance (Active).

RESULTS

The simulation results demonstrated that all three exosuits were able to produce significant moments of ankle plantarflexion. Among these, the PT scheme exhibited the highest moments in all dimensions, followed by the PTS and IS schemes. The experimental findings confirmed the effectiveness of all three exosuit schemes in assisting ankle plantarflexion. Additionally, as the assistive force lines approached the subtalar joint, there was a decrease in ankle motion assisted by the exosuits in non-plantarflexion directions, along with a reduction in the average distance of ankle angle curves relative to active ankle motion. Furthermore, the linear correlation coefficients between inversion and plantarflexion, adduction and plantarflexion, and adduction and inversion gradually converged toward active ankle plantarflexion motion.

CONCLUSIONS

Our research indicates that the position of the exosuit force line to the subtalar joint has a significant impact on ankle inversion and adduction. Among all three schemes, the IS, which has the closest distance to the subtalar joint axes, has the greatest kinematic similarity to active ankle plantarflexion and might be a better choice for ankle assistance and rehabilitation.

Impact of specialized fatigue and backhand smash on the ankle biomechanics of female badminton players

During fatigued conditions, badminton players may experience adverse effects on their ankle joints during smash landings. In addition, the risk of ankle injury may vary with different landing strategies. This study aimed to investigate the influence of sport-specific fatigue factors and two backhand smash actions on ankle biomechanical indices. Thirteen female badminton players (age: 21.2 ± 1.9 years; height: 167.1 ± 4.1 cm; weight: 57.3 ± 5.1 kg; BMI: 20.54 ± 1.57 kg/m2) participated in this study. An 8-camera Vicon motion capture system and three Kistler force platforms were used to collect kinematic and kinetic data before and after fatigue for backhand rear-court jump smash (BRJS) and backhand lateral jump smash (BLJS). A 2 × 2 repeated measures analysis of variance was employed to analyze the effects of these smash landing actions and fatigue factors on ankle biomechanical parameters. Fatigue significantly affected the ankle-joint plantarflexion and inversion angles at the initial contact (IC) phase (p < 0.05), with both angles increasing substantially post-fatigue. From a kinetic perspective, fatigue considerably influenced the peak plantarflexion and peak inversion moments at the ankle joint, which resulted in a decrease the former and an increase in the latter after fatigue. The two smash landing actions demonstrated different landing strategies, and significant main effects were observed on the ankle plantarflexion angle, inversion angle, peak dorsiflexion/plantarflexion moment, peak inversion/eversion moment, and peak internal rotation moment (p < 0.05). The BLJS landing had a much greater landing inversion angle, peak inversion moment, and peak internal rotation moment compared with BRJS landing. The interaction effects of fatigue and smash actions significantly affected the muscle force of the peroneus longus (PL), with a more pronounced decrease in the force of the PL muscle post-fatigue in the BLJS action(post-hoc < 0.05). This study demonstrated that fatigue and smash actions, specifically BRJS and BLJS, significantly affect ankle biomechanical parameters. After fatigue, both actions showed a notable increase in IC plantarflexion and inversion angles and peak inversion moments, which may elevate the risk of lateral ankle sprains. Compared with BRJS, BLJS poses a higher risk of lateral ankle sprains after fatigue.

Investigation into the effect of deltoid ligament injury on rotational ankle instability using a three-dimensional ankle finite element model

Background

Injury to the lateral collateral ligament of the ankle may cause ankle instability and, when combined with deltoid ligament (DL) injury, may lead to a more complex situation known as rotational ankle instability (RAI). It is unclear how DL rupture interferes with the mechanical function of an ankle joint with RAI.

Purpose

To study the influence of DL injury on the biomechanical function of the ankle joint.

Methods

A comprehensive finite element model of an ankle joint, incorporating detailed ligaments, was developed from MRI scans of an adult female. A range of ligament injury scenarios were simulated in the ankle joint model, which was then subjected to a static standing load of 300 N and a 1.5 Nm internal and external rotation torque. The analysis focused on comparing the distribution and peak values of von Mises stress in the articular cartilages of both the tibia and talus and measuring the talus rotation angle and contact area of the talocrural joint.

Results

The dimensions and location of insertion points of ligaments in the finite element ankle model were adopted from previous anatomical research and dissection studies. The anterior drawer distance in the finite element model was within 6.5% of the anatomical range, and the talus tilt angle was within 3% of anatomical results. During static standing, a combined rupture of the anterior talofibular ligament (ATFL) and anterior tibiotalar ligament (ATTL) generates new stress concentrations on the talus cartilage, which markedly increases the joint contact area and stress on the cartilage. During static standing with external rotation, the anterior talofibular ligament and anterior tibiotalar ligament ruptured the ankle's rotational angle by 21.8% compared to an intact joint. In contrast, static standing with internal rotation led to a similar increase in stress and a nearly 2.5 times increase in the talus rotational angle.

Conclusion

Injury to the DL altered the stress distribution in the tibiotalar joint and increased the talus rotation angle when subjected to a rotational torque, which may increase the risk of RAI. When treating RAI, it is essential to address not only multi-band DL injuries but also single-band deep DL injuries, especially those affecting the ATTL.

Causal Relationships Between Physical Activity and Arthrokinematic Integrity of the Ankle Joint-Foot Complex Across Normal and Pathological Phenomena: A Case-Control Analysis

Introduction Muscles, ligaments, tendons, bones, and cartilage undergo age-related changes, affecting the foot-ankle joint complex biomechanics in both genders. While international studies have extensively researched these dynamics, Indian studies are limited. Our study aims to fill this gap by analyzing the anthropometric and biomechanical function of the foot-ankle joint complex in normal individuals and those with painful pathologies at All India Institute of Medical Sciences (AIIMS) Rajkot's OPD. Methods In a two-year case-control study of the cross-sectional type conducted at AIIMS Rajkot's OPD, 158 patients with similar pain intensity on the Numeric Pain Rating Scale were examined. Anthropometric and biomechanical measurements were taken for both affected and non-affected foot and ankle joints. Cases comprised patients with foot and ankle joint pain, while controls were selected based on predefined criteria and were without such pain. Ethical approval was acquired from the Institutional Ethical Committee of AIIMS Rajkot. Results The sprain of the ankle joint and foot was the most common musculoskeletal pathology (65 out of 158 cases, i.e., 41.13%) affecting the ankle joint-foot complex. Patients involved in occupations requiring higher physical inactivity suffer more commonly from ankle joint-foot pathologies. The mean difference in the range of motion, i.e., dorsiflexion, plantar flexion, inversion, and eversion, between affected and non-affected feet was found to be lower in the patients who belonged to occupations involving low physical activity compared to those patients having occupations with high physical activity. Conclusion Reduced physical activity increases the stiffness and reduces the flexibility of the tendons, muscles, and ligaments of any joint (the ankle joint-foot complex in this study) and is associated with a higher incidence of musculoskeletal pathologies.

Development and validation of a novel ankle joint musculoskeletal model

An improved understanding of contact mechanics in the ankle joint is paramount for implant design and ankle disorder treatment. However, existing models generally simplify the ankle joint as a revolute joint that cannot predict contact characteristics. The current study aimed to develop a novel musculoskeletal ankle joint model that can predict contact in the ankle joint, together with muscle and joint reaction forces. We modelled the ankle joint as a multi-axial joint and simulated contact mechanics between the tibia, fibula and talus bones in OpenSim. The developed model was validated with results from experimental studies through passive stiffness and contact. Through this, we found a similar ankle moment-rotation relationship and contact pattern between our study and experimental studies. Next, the musculoskeletal ankle joint model was incorporated into a lower body model to simulate gait. The ankle joint contact characteristics, kinematics, and muscle forces were predicted and compared to the literature. Our results revealed a comparable peak contact force and the same muscle activation patterns in four major muscles. Good agreement was also found in ankle dorsi/plantar-flexion and inversion/eversion. Thus, the developed model was able to accurately model the ankle joint and can be used to predict contact characteristics in gait.

Quantifying walking speeds in relation to ankle biomechanics on a real-time interactive gait platform: a musculoskeletal modeling approach in healthy adults

Background: Given the inherent variability in walking speeds encountered in day-to-day activities, understanding the corresponding alterations in ankle biomechanics would provide valuable clinical insights. Therefore, the objective of this study was to examine the influence of different walking speeds on biomechanical parameters, utilizing gait analysis and musculoskeletal modelling. Methods: Twenty healthy volunteers without any lower limb medical history were included in this study. Treadmill-assisted gait-analysis with walking speeds of 0.8 m/s and 1.1 m/s was performed using the Gait Real-time Analysis Interactive Lab (GRAIL®). Collected kinematic data and ground reaction forces were processed via the AnyBody® modeling system to determine ankle kinetics and muscle forces of the lower leg. Data were statistically analyzed using statistical parametric mapping to reveal both spatiotemporal and magnitude significant differences. Results: Significant differences were found for both magnitude and spatiotemporal curves between 0.8 m/s and 1.1 m/s for the ankle flexion (p < 0.001), subtalar force (p < 0.001), ankle joint reaction force and muscles forces of the M. gastrocnemius, M. soleus and M. peroneus longus (α = 0.05). No significant spatiotemporal differences were found between 0.8 m/s and 1.1 m/s for the M. tibialis anterior and posterior. Discussion: A significant impact on ankle joint kinematics and kinetics was observed when comparing walking speeds of 0.8 m/s and 1.1 m/s. The findings of this study underscore the influence of walking speed on the biomechanics of the ankle. Such insights may provide a biomechanical rationale for several therapeutic and preventative strategies for ankle conditions.

Chronic effects of stretching on range of motion with consideration of potential moderating variables: A systematic review with meta-analysis

BACKGROUND

It is well known that stretch training can induce prolonged increases in joint range of motion (ROM). However, to date more information is needed regarding which training variables might have greater influence on improvements in flexibility. Thus, the purpose of this meta-analysis was to investigate the effects of stretch training on ROM in healthy participants by considering potential moderating variables, such as stretching technique, intensity, duration, frequency, and muscles stretched, as well as sex-specific, age-specific, and/or trained state-specific adaptations to stretch training.

METHODS

We searched through PubMed, Scopus, Web of Science, and SportDiscus to find eligible studies and, finally, assessed the results from 77 studies and 186 effect sizes by applying a random-effect meta-analysis. Moreover, by applying a mixed-effect model, we performed the respective subgroup analyses. To find potential relationships between stretch duration or age and effect sizes, we performed a meta-regression.

RESULTS

We found a significant overall effect, indicating that stretch training can increase ROM with a moderate effect compared to the controls (effect size = -1.002; Z = -12.074; 95% confidence interval: -1.165 to -0.840; p < 0.001; I2 = 74.97). Subgroup analysis showed a significant difference between the stretching techniques (p = 0.01) indicating that proprioceptive neuromuscular facilitation and static stretching produced greater ROM than did ballistic/dynamic stretching. Moreover, there was a significant effect between the sexes (p = 0.04), indicating that females showed higher gains in ROM compared to males. However, further moderating analysis showed no significant relation or difference.

CONCLUSION

When the goal is to maximize ROM in the long term, proprioceptive neuromuscular facilitation or static stretching, rather than ballistic/dynamic stretching, should be applied. Something to consider in future research as well as sports practice is that neither volume, intensity, nor frequency of stretching were found to play a significant role in ROM yields.

Adaptive state restricted barrier Lyapunov-based control of a Stewart platform used as ankle-controlled mobilizer

In this research project, a closed-chain robotic active ankle orthosis with six degrees of freedom is designed, constructed, numerically valued, instrumented, and experimentally validated. The mechanical arrangement to implement the orthosis corresponds to a six-legged Stewart platform. An adaptive gain control strategy with state constraints based on a state-dependent gains control (that behaves as a diverging function as the states approach the state restrictions) operates the device's motion. The convergence to an invariant positive set centered at the origin of the tracking error space is validated using the stability analysis based on the second method of Lyapunov, with the implementation of a state barrier Lyapunov-like function. The ultimate boundedness of the tracking error is proven with an endorsed gains adjustment method leading to a reachable minimum size of the ultimate bound. Hence, the impact of the state constraints and the formal reason for applying the controller on the suggested orthosis are all established. The orthosis is also controlled using a conventional state feedback strategy to assess the tracking error for an external disturbance and contrast its performance with the proposed control approach. The technology is tested on a few carefully chosen volunteers, successfully limiting the range of motion within a pre-defined region based on the scope of movement reported by patients with ankle illnesses discovered in the literature. Based on a unique mechatronic device, the created system offers a fresh approach to treating this class of impairments.

Compliant Intramedullary Stems for Joint Reconstruction

The longevity of current joint replacements is limited by aseptic loosening, which is the primary cause of non-infectious failure for hip, knee, and ankle arthroplasty. Aseptic loosening is typically caused either by osteolysis from particulate wear, or by high shear stresses at the bone-implant interface from over-constraint. Our objective was to demonstrate feasibility of a compliant intramedullary stem that eliminates over-constraint without generating particulate wear. The compliant stem is built around a compliant mechanism that permits rotation about a single axis. We first established several models to understand the relationship between mechanism geometry and implant performance under a given angular displacement and compressive load. We then used a neural network to identify a design space of geometries that would support an expected 100-year fatigue life inside the body. We additively manufactured one representative mechanism for each of three anatomic locations, and evaluated these prototypes on a KR-210 robot. The neural network predicts maximum stress and torsional stiffness with 2.69% and 4.08% error respectively, relative to finite element analysis data. We identified feasible design spaces for all three of the anatomic locations. Simulated peak stresses for the three stem prototypes were below the fatigue limit. Benchtop performance of all three prototypes was within design specifications. Our results demonstrate the feasibility of designing patient- and joint-specific compliant stems that address the root causes of aseptic loosening. Guided by these results, we expect the use of compliant intramedullary stems in joint reconstruction technology to increase implant lifetime.

The role of ankle and knee muscle characteristics in spatiotemporal gait parameters at different walking speeds: A cross-sectional study

BACKGROUND

Understanding the intricate interplay between ankle and knee muscle characteristics and their impact on gait parameters is crucial for enhancing our comprehension of human locomotion, particularly in the context of varying walking speeds among healthy young adults.

RESEARCH QUESTION

The study aimed to identify the relative importance of ankle and knee flexor and extensor muscle characteristics (e.g., strength estimated by peak torque [PT] and rate of torque development [RTD]) in the spatiotemporal gait parameters and variability in self-selected (SSWS) and fast walking speeds (FWS) in healthy young adults.

METHODS

One hundred and thirty-nine adults (75 men - 54% and 64 women - 46%; 29.04 ± 9.55 years) were assessed about their muscle characteristics (PT and RTD by an isokinetic dynamometer) and spatiotemporal gait parameters at different walking speeds (SSWS and FWS by an instrumented walkway).

RESULTS

Data analysis indicated a weak relationship between the PT and RTD of the ankle and knee and spatiotemporal gait parameters and variability in both walking conditions (SSWS: R2 0.14-0.05; FWS: R2 0.40-0.05). The strength of the knee muscles was more relevant when walking at a self-selected speed, while the strength of the ankle muscles played a more prominent role when walking at a fast pace.

SIGNIFICANCE

The findings underscore the critical role of ankle muscles (plantar and dorsiflexors) at fast walking speeds. Therefore, targeted interventions for strength and optimization of these muscles are paramount.

Ankle Telemedicine Planning Considerations

A virtual medical visit, also known as telemedicine or telehealth, is a valuable alternative method of providing health care to patients who do not have easy access to a hospital, or during times when limited social interaction is crucial such as our current COVID-19 pandemic. A virtual approach to evaluating musculoskeletal system ailments is particularly challenging, for diagnosis of these conditions generally rely greatly on physical examination, which may be challenging. However, a properly planned and executed telemedicine visit will yield successful results in most cases. Our aim is to produce a document with instructions and suggestions, including physical examination maneuvers, to help physicians carry out a proper virtual medical visit with patients complaining of ankle musculoskeletal problems. Virtual visits should not be thought of as a replacement for traditional face-to-face medical consultations, but rather a complementary method to provide health care when deemed appropriate. By following this guide, and tailoring it to the specific case at hand, medical providers should be able to effectively carry out a successful telemedicine consultation for musculoskeletal ailments relating to the ankle.Levels of Evidence: Level V.

Differences in intra-foot movement strategies during locomotive tasks among chronic ankle instability, copers and healthy individuals

Individuals with chronic ankle instability (CAI) suffer from the resulting sequela of repetitive lateral ankle sprains (LAS), whilst copers appear to cope with initial LAS successfully. Therefore, the aim of this study was to explore the intra-foot biomechanical differences among CAI, copers, and healthy individuals during dynamic tasks. Twenty-two participants per group were included and required to perform cutting and different landing tasks (DL: drop landing; FL: forward jump followed a landing). A five-segment foot model with 8 degrees of freedom was used to explore the intra-foot movement among these three groups. Smaller dorsiflexion angles were found in copers (DL tasks and prelanding task) and CAI (DL and FL task) compared to healthy participants. Copers presented a more eversion position compared to others during these dynamic tasks. During the descending phase of DL task, greater dorsiflexion angles in the metatarsophalangeal joint were found in copers compared to the control group. Joint moment difference was only found in the subtalar joint during the descending phase of FL task, presenting more inversion moments in copers compared to healthy participants. Copers rely on more eversion positioning to prevent over-inversion of the subtalar joint compared to CAI. Further, the foot became more unstable when conducting sport-related movements, suggesting that foot stability seems to be sensitive to the task types. These findings may help in designing and implementing interventions to restore functions of the ankle joint in CAI individuals.

Foot biomechanics in patients with advanced subtalar- and mid-tarsal joint osteoarthritis and poorly responding to conservative treatment

BACKGROUND

A comprehensive insight into the effects of subtalar- and mid-tarsal joint osteoarthritis on lower limb's biomechanical characteristics during walking is lacking. Our goal was to assess joint kinematics and kinetics and compensatory mechanisms in patients with subtalar and mid-tarsal joint osteoarthritis.

METHODS

Patients with symptomatic and radiographically confirmed osteoarthritis of the subtalar and mid-tarsal (n = 10) and an asymptomatic control group (n = 10) were compared. Foot joint kinematics and kinetics during the stance phase of walking were quantified using a four-segment foot model.

RESULTS

During pre-swing phase, the tibio-talar range of motion in the sagittal plane of the patient group decreased significantly (P = 0.001), whereas the tarso-metatarsal joint range of motion in the sagittal plane was greater in the pre-swing phase (P = 0.003). The mid-tarsal joint showed lower transverse plane range of motion in the patient group during the loading response and pre-swing phase (P < 0.001 resp. P = 0.002). The patient group showed a lower Tibio-talar joint peak plantarflexion moment (P = 0.004), peak plantarflexion velocity (P < 0.001) and peak power generation in the sagittal plane (P < 0.001), and a lower mid-tarsal joint peak adduction and abduction velocity (P < 0.001 resp. P < 0.001) and peak power absorption (P < 0.001).

CONCLUSIONS

These findings suggest that patients with subtalar and mid-tarsal joint osteoarthritis adopt a cautious walking strategy potentially dictated by pain, muscle weakness, kinesiophobia and stiffness. Since this poorly responding population faces surgical intervention on the short term, we recommend careful follow-up after fusion surgery since biomechanical outcome measures associated to this post-surgical stage is lacking.

Cross-cultural adaptation, reliability, and validity of the Turkish version of the Cumberland Ankle Instability Tool

OBJECTIVES

The objective of the study was to cross-culturally adapt and assess the validity and reliability of the Turkish version of the CAIT (CAIT-TR).

METHODS

The CAIT was translated and adapted into Turkish according to accepted cross-cultural adaptation guidelines of self-reported measures. A total of 130 individuals, including healthy participants (n = 40) and with chronic ankle instability (CAI) (n = 90), were recruited in this study. The internal consistency and test-retest reliability of the CAIT-TR were assessed using Cronbach's alpha and intraclass correlation coefficients (ICC), respectively. To assess convergent validity, hypotheses were tested regarding expected correlations between CAIT-TR, Foot and Ankle Outcome Score (FAOS) subscales, and the Visual Analogue Scale (VAS). Discriminative validity was evaluated with the hypothesis that the CAIT-TR can distinguish between subjects with and without CAI and also calculated a cut-off score for CAI. The dimensional structure of the CAIT-TR was investigated with confirmatory factor analysis. Additionally, minimal detectable change (MDC), floor/ceiling effects, and measurement error values were determined.

RESULTS

The CAIT-TR demonstrated high Internal consistency (Cronbach's alpha = 0.854) and test-retest reliability (ICC = 0.919). Regarding convergent validity, the CAIT-TR exhibited a moderate-strong correlation with both the FAOS and VAS. The confirmatory factor analysis supported the unidimensional structure of the questionnaire. The identified cut-off value for the CAIT-TR was 25, and the MDC for individual-level CAIT-TR scores was determined to be 1.87. No floor or ceiling effects were observed.

CONCLUSION

The CAIT-TR is a valid and reliable questionnaire for the assessment of ankle instability within the Turkish population.

Physiotherapy Management Focusing on Early Mobilisation in Complex Pelvic and Pott's Fracture

Pelvic fractures (PFs), involving the disruption of the bony structures in the pelvic region, are complex injuries often associated with high-energy trauma. Such fractures can significantly impact a patient's mobility and overall quality of life. Concurrently, fractures of the malleoli, specifically the lateral and medial aspects of the ankle, are common lower extremity injuries that can result from various mechanisms, including twisting or direct trauma. This case report presents the multidisciplinary approach employed in the successful treatment of a 26-year-old male patient with a rare combination of PFs involving both anterior and posterior columns, along with lateral and medial malleolus fractures. The patient underwent a series of surgical interventions to stabilise the fractures, followed by a tailored physiotherapy management plan. The report discusses the postoperative care strategies and the crucial role of physiotherapy in the rehabilitation process.

Biomechanical Forces in the Tissue Engineering and Regeneration of Shoulder, Hip, Knee, and Ankle Joints

Tear on the tendon, ligament and articular cartilage of the joints do not heal by itself and new modalities of treatment are required to address the need for full restoration of joint functions. Accompanied by degenerative diseases, the healing of these tissues does not occur naturally and hence requires surgical interventions, but with associated morbidity. Tissue engineering strategies are now focusing on the effective incorporation of biomechanical stimulation by the application of biomechanical forces relevant to the tissue of interest to regenerate and engineer functional tissues. Bioreactors are being continuously developed to accomplish this goal. Although bioreactors have been developed, the advancement in the field of biomaterial, basic science, and cell engineering warrant further refinement for their effective use. In this article we reviewed the application of biomechanical forces in the tissue engineering and regeneration of the joints such as rotator cuff of shoulder, ball and socket joint of the hip, articular cartilage of knee, and the ankle joints.

Comparison of wear on articular cartilage by titanium alloy, ultra-high-molecular-weight polyethylene, and carbon fibre reinforced polyether-ether-ketone: A pilot study

Artificial implant materials may articulate against native articular cartilage in certain clinical scenarios and the selection of an implant material that results in the least wear on articular cartilage is preferred to maintain normal joint architecture and function. This project compared the wear on porcine femoral condyles induced by articulation against porcine patellae, titanium alloy (Ti6Al4V), ultra high molecular weight polyethylene (UHMWPE), and carbon fibre reinforced polyether-ether-ketone (CFR-PEEK) through an ex vivo experimental setup. A sinusoidal compressive load of 30-160 N, representing an approximate joint pressure of 0.19-1 MPa at a frequency of 3 Hz coupled with a rotational displacement of +/- 10⁰ at 3 Hz was used to simulate physiological joint motion. Wear was characterized via gross examination and histologically using the OARSI scoring system after 43,200 cycles. CFR-PEEK resulted in the most significant wear on articular cartilage compared to titanium alloy and UHMWPE whereas titanium alloy and UHMWPE resulted in similar levels of wear. All materials caused more wear compared to cartilage-on-cartilage testing. The wear mechanism was characterized by progressive loss of proteoglycan content in cartilage in histology samples.

Tunable, Textile-Based Joint Impedance Module for Soft Robotic Applications

The design of soft actuators is often focused on achieving target trajectories or delivering specific forces and torques, rather than controlling the impedance of the actuator. This article outlines a new soft, tunable pneumatic impedance module based on an antagonistic actuator setup of textile-based pneumatic actuators intended to deliver bidirectional torques about a joint. Through mechanical programming of the actuators (select tuning of geometric parameters), the baseline torque to angle relationship of the module can be tuned. A high bandwidth fluidic controller that can rapidly modulate the pressure at up to 8 Hz in each antagonistic actuator was also developed to enable tunable impedance modulation. This high bandwidth was achieved through the characterization and modeling of the proportional valves used, derivation of a fluidic model, and derivation of control equations. The resulting impedance module was capable of modulating its stiffness from 0 to 100 Nm/rad, at velocities up to 120°/s and emulating asymmetric and nonlinear stiffness profiles, typical in wearable robotic applications.

A Bio-Inspired Arched Foot with Individual Toe Joints and Plantar Fascia

This paper presents the design and testing of an arched foot with several biomimetic features, including five individual MTP (toe) joints, four individual midfoot joints, and plantar fascia. The creation of a triple-arched foot represents a step further in bio-inspired design compared to other published designs. The arched structure creates flexibility that is similar to human feet with a vertical deflection of up to 12 mm. The individual toe joints enable abduction-adduction in the forefoot and therefore a natural pronation motion. Adult female bone data was obtained and converted into a CAD model to accurately identify the location of bones, joints, and arches. An analytical model is presented that gives the relationship between the vertical stiffness and horizontal stiffness of the longitudinal arches and therefore allows the optimization of stiffness elements. Experimental tests have demonstrated a vertical arch stiffness of 76 N/mm which is similar to adult human feet. The range of movement of the foot is similar to human feet with the following values: dorsi-plantarflexion (28°/37°), inversion-eversion (30°/15°), and abduction-adduction (30°/39°). Tests have also demonstrated a three-point contact with the ground that is similar to human feet.

Ankle-Foot-Orthosis "Hermes" Compensates Pathological Ankle Stiffness of Chronic Stroke-A Proof of Concept

Individuals with an upper motor neuron syndrome, e.g., stroke survivors, may have a pathological increase of passive ankle stiffness due to spasticity, that impairs ankle function and activities such as walking. To improve mobility, walking aids such as ankle-foot orthoses and orthopaedic shoes are prescribed. However, these walking aids generally limit the range of motion (ROM) of the foot and may therewith negatively influence activities that require a larger ROM. Here we present a new ankle-foot orthosis "Hermes", and its first experimental results from four hemiparetic chronic stroke patients. Hermes was designed to facilitate active ankle dorsiflexion by mechanically compensating the passive ankle stiffness using a negative-stiffness mechanism. Four levels of the Hermes' stiffness compensation (0%, 35%, 70% and 100%) were applied to evaluate active ROM in a robotic ankle manipulator and to test walking feasibility on an instrumented treadmill, in a single session. The robotic tests showed that Hermes successfully compensated the ankle joint stiffness in all four patients and improved the active dorsiflexion ROM in three patients. Three patients were able to walk with Hermes at one or more Hermes' stiffness compensation levels and without reducing their preferred walking speeds compared to those with their own walking aids. Despite a small sample size, the results show that Hermes holds great promise to support voluntary ankle function and to benefit walking and daily activities.

Effect of Different Foot Orthosis Inverted Angles on Walking Kinematics in Females with Flexible Flatfeet

Background

Although the inverted technique was shown to be more effective compared to other orthotic designs for the treatment of flatfeet, the biomechanical mechanisms underlying the therapeutic effect of the inverted angle orthoses is still unclear. Therefore, the aim of this study was to examine the effect of different inverted angles of foot orthoses on walking kinematics in females with flexible flatfeet.

Methods

Thirty-one female adults with flexible flatfeet aged 18-35 years old participated in this study. Kinematic data of the hip, knee, and ankle were collected via BTS motion-capture system during walking under three test conditions in random order: with shoes only; with 15° inverted orthoses; and with 25° inverted orthoses.

Results

Compared to the shoes only condition, both the 15° and 25° inverted orthotic conditions significantly decreased the maximum ankle plantarflexion angle during loading response, maximum ankle dorsiflexion angle during mid-stance, maximum ankle external rotation angle, and maximum ankle internal rotation angle. The maximum ankle plantarflexion angle at toe-off showed a significant decrease with the 25° inverted angle orthosis compared to both the 15° inverted angle and shoes only conditions. No significant differences were found in the knee kinematic variables, maximum hip extension angle, and maximum hip adduction angle between test conditions.

Conclusion

Using inverted orthoses at 15° and 25° inverted angles resulted in significant changes in ankle joint kinematics during walking in female adults with flexible flatfeet. A 25° inverted angle orthosis significantly decreased ankle plantarflexion during push-off, potentially impacting gait mechanics. This suggests that a smaller inverted angle may be more effective for managing flexible flatfeet in female adults.

A Single-Center Comparative Study: Outcome Analysis of Fixation Techniques for Tibiotalocalcaneal Arthrodesis

Introduction Tibiotalocalcaneal arthrodesis (TTCA) is a well-known and accepted surgical technique for end-stage ankle osteoarthritis. The aim of this study is to compare the postoperative clinical and radiological comparison of retrograde intramedullary nailing (RIMN) and plate/cannulated screw (P/cS) fixation methods in patients undergoing TTCA. Methods Patients with end-stage ankle osteoarthritis due to traumatic causes or rheumatic diseases between December 2012 and March 2019 were included in the retrospective study. Patients who underwent isolated tibiotalar or isolated subtalar arthrodesis were not included in the study. Functional scores of patients with bone fusion were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) and Short Form-36 (SF-36) quality of life score surveys, administered either in person or by phone. From the radiological point of view, it was evaluated whether the union was achieved with the two-view ankle radiograph. There were 48 patients who underwent ankle arthrodesis in the clinical archive. A total of 31 patients were excluded from the study due to failure to attend follow-up, inability to be reached, or non-compliance with study criteria. The mean age of the patients participating in the study was 44.12 ± 12.95 years, the follow-up time was 40.06 ± 27.31 months, the union time was 5.19 ± 3.17 months, and the AOFAS score was 53.12 ± 13.87. SF-36 scores were evaluated among their own subunits. Results A total of 17 patients were enrolled in the study, of whom 13 were male (76.47%) and 4 were female (23.53%). There was no significant effect of the fixation methods (RIMN or P/cS) selected for TTCA on union times (p>0.05). However, there were significant differences in some parameters of the SF-36 when compared by gender. According to this, the scores of men in physical function (PF), mental health (MH), and general health perception (GHP) were higher than those of women. When AOFAS and SF-36 scores were compared by fixation type, no statistically significant difference was found (p>0.05). Conclusion This study investigated the impact of the fixation method on clinical and radiological outcomes in TTCA. We found that both methods were clinically similar in terms of bone union time and surgical efficacy. However, men had better physical function, mental health, and general health perception after TTCA than women.

Investigating the Effect of Novel Gamified Stepper on Lower Limb Biomechanics in Seated Healthy Subjects

The present study introduces a new gamified stepper device designed for bilateral lower limb rehabilitation, which is combined with a 3-D exergame. To the best of our knowledge, this is the initial study to utilize the stepping exercise for seated lower limb rehabilitation. The device comprises a stepping mechanism and a magnetic encoder. The modified stepper facilitates the bilateral training in the lower limb within its workspace. The magnetic encoder provides real-time rotational angle data during the exercise. A task-specific exergame platform was created and integrated with the device to enhance user compliance and engagement with the exercise. Experiments were conducted with ten healthy individuals with no history of lower limb injury to evaluate the system's feasibility for providing bilateral training and the effectiveness of the exergame platform. Participants were asked to perform bilateral lower limb exercise with a metronome and gamified stepper device in a seated position. Lower limb range of motion (ROM) and EMG activations were recorded during the exercises. The results indicate that the device was capable of providing cyclical ROM training with reduced muscle activation of the lower limb, and the exergame platform increased motivation to continue the exercises. This study can serve as the foundation for developing a robotic version of the proposed stepper device.

Statistical shape modeling of mean shape and principal variability of the human talar bone in the Chinese population

PURPOSE

The talar bone plays a crucial role in ankle biomechanics and stability. Understanding the shape variability of the talar bone within specific populations is essential for various clinical applications. In this study, we aimed to investigate the mean shape and principal variability of the human talar bone in the Chinese population using statistical shape modeling (SSM).

METHODS

CT scans of 214 tali were included to create SSM models. Principal component analysis was used to describe shape variation among the male, female, and overall groups.

RESULTS

The largest amount of variation among three groups ranges from 17.2%-18.8% of each variation. The first seven principal components (modes) captured 62.4%-67.5% of the cumulative variance. No dominant shape of the talus was found. Male tali generally have a larger size than the female tali, with the exception of the articular surface of the anterior subtalar joint.

CONCLUSIONS

SSM is an effective method of finding mean shape and principal variability. Considerable variabilities were noticed among these three groups and all principal modes of variation. No dominant talar model was found to represent the majority of tali, regardless the gender. Such information is crucial to improve the current understanding of talar pathologies and their treatment strategies.

Effects of Progressive Deltoid Ligament Sectioning on Weber B Ankle Fracture Stability

BACKGROUND

Conventionally, transsyndesmotic fibula fractures with concomitant signs of deltoid ligament injury have been considered unstable and thus treated operatively. Recent studies have indicated that partial deltoid ligament rupture is common and may allow for nonoperative treatment of stress-unstable ankles if normal tibiotalar alignment is obtained in the weightbearing position. Biomechanical support for this principle is scarce. The purpose of this study was to evaluate the biomechanical effects of gradually increasing deltoid ligament injury in transsyndesmotic fibula fractures.

METHODS

Fifteen cadaveric ankle specimens were tested using an industrial robot. All specimens were tested in 4 states: native, SER2, SER4a, and SER4b models. Ankle stability was measured in lateral translation, valgus, and internal and external rotation stress in 3 talocrural joint positions: 20 degrees plantarflexion, neutral, and 10 degrees dorsiflexion. Talar shift and talar valgus tilt in the talocrural joint was measured using fluoroscopy.

RESULTS

In most tests, SER2 and SER4a models resulted in a small instability increase compared to native joints and thus were deemed stable according to our predefined margins. However, SER4a models were unstable when tested in the plantarflexed position and for external rotation in all positions. In contrast, SER4b models had large-magnitude instability in all directions and all tested positions and were thus deemed unstable.

CONCLUSION

This study demonstrated substantial increases in instability between the SER4a and SER4b states. This controlled cadaveric simulation suggests a significant ankle-stabilizing role of the deep posterior deltoid after oblique transsyndesmotic fibular fracture and transection of the superficial and anterior deep deltoid ligaments.

CLINICAL RELEVANCE

The study provides new insights into how the heterogenicity of deltoid ligament injuries can affect the natural stability of the ankle after Weber B fractures. These findings may be useful in developing more targeted and better treatment strategies.

Evaluating the Efficacy of Tension Band Wiring Fixation for Chaput Tubercle Fractures

BACKGROUND

Chaput tubercle fractures, located at the attachment site of the anterior inferior tibiofibular ligament (AITFL) on the distal tibia, have the potential to destabilize the syndesmosis joint. This study aims to assess the effectiveness of tension band wiring (TBW) as a surgical intervention for managing Chaput fractures and the consequent syndesmosis instability.

METHODS

A retrospective review of patient charts was undertaken for those who had undergone ankle fracture surgery from April 2019 through May 2022. The surgical procedure involved direct fixation of the Chaput fractures using the TBW method. Radiological assessments were performed using postoperative simple radiographs and computed tomography (CT) scans, while clinical outcomes were evaluated using the Olerud-Molander Ankle Score (OMAS) and the visual analog scale (VAS).

RESULTS

The study included 21 patients. The average OMAS improved significantly, rising from 5.95 preoperatively to 83.57 postoperatively. Similarly, the average VAS score dropped from 7.95 before the surgery to 0.19 thereafter. Minor wound complications were reported by three patients, and one case of superficial infection was resolved with antibiotic therapy.

CONCLUSIONS

Our findings suggest that the TBW technique is an effective surgical approach for treating Chaput fractures and associated syndesmosis instability. It provides reliable fixation strength and leads to improved long-term functional outcomes. Further research is needed to compare the TBW technique with alternative methods and optimize the treatment strategies for these complex ankle fractures.

Design of a lightweight universal talus implant using topology optimization

Total talus replacement is a promising alternative treatment for talus fractures complicated by avascular necrosis and collapse. This surgical option replaces the human talus bone with a customized talus implant and can maintain ankle joint functionality compared to traditional treatment (e.g., ankle fusion). However, the customized implant is costly and time-consuming due to its customized nature. To circumvent these drawbacks, universal talus implants were proposed. While they showed clinically satisfactory results, existing talus implants are heavier than biological talus bones as they are solid inside. This can lead to unequal weight between the implant and biological talus bone, and therefore leading to other complications. The reduction of the implants' weight without compromising its performance and congruency with surrounding bones is a potential solution. Therefore, this study aims to design a lightweight universal talus implant using topology optimization. This is done through establishing the loading and boundary conditions for three common foot postures: neutral, dorsi- and plantar-flexion. The optimized implant performance in terms of mass, contact characteristics with surrounding joint cartilage and stress distributions is studied using a 3D Finite Element (FE) model of the ankle joint. The mass of the optimized implant is reduced by approximately 66.6% and its maximum stresses do not exceed 70 MPa, resulting in a safety factor of 15.7. Moreover, the optimized and solid implants show similar contact characteristics. Both implants produced peak contact pressures that were approximately 19.0%-196% higher than those produced by the biological talus. While further mechanical testing under in-vivo loading conditions is required to determine clinical feasibility, preliminarily, the use of a lightweight universal implant is expected to provide the patient with a more natural feel, and a reduced waiting period until surgery.

Assessing Motor Function in Frail Older Adults in Their Home Settings: Challenges, Strategies and Recommendations

Assessing motor competence is essential for evaluating the effectiveness of physical activity interventions that aim to maintain or improve older adults' function. However, assessing motor competence in older adults who have difficulties walking or standing is challenging, because few instruments or guidelines are appropriate for these frail older adults. This article aims to describe challenges in evaluating motor function among frail older adults, discuss strategies for adapting motor function assessments to their home settings, and provide recommendations for future clinical trials so that older adults with ambulatory difficulties can benefit from motor function assessment and physical activity programs. Data came from the baseline assessment of 116 participants of an ongoing clinical trial, "Promoting Seniors' Health with Home Care Aides (Pro-Home)". Our results demonstrated that the Pro-Home study involved participants who would be typically excluded from clinical trials and that the two instruments selected or developed for Pro-Home (Short Physical Performance Battery, Pro-Home Ankle Range of Motion Measure) captured a wide range of lower extremity motor competence with no or few missing data. Recommendations for future studies include knowing the target population thoroughly, developing trust and rapport with all parties involved, and continuously collaborating with interviewers who conduct assessments.

Imaging of the Ankle Ligaments and Cartilage Injuries as an Aid to Ankle Preservation Surgery

Ankle sprains are among the most common musculoskeletal injuries and can lead to ankle ligament and cartilage injuries. Imaging plays an important role in differentiating ligament injuries from other causes of ankle pain such as fractures, osteochondral lesions or tendon injuries that helps guide further management. Chronic untreated ankle ligamentous and cartilage injuries can further progress to ankle osteoarthritis, hence the need for timely diagnosis and treatment. Surgical treatment is often required in patients not responding to conservative treatment and ranges from repair and reconstruction procedures for ligament injuries to arthroscopic debridement and repair procedures for cartilage injuries. Cartilage defects and deficiency may be augmented depending on the extent of cartilage loss and associated subchondral changes on MRI. Awareness of operative techniques utilized is essential to interpret imaging findings in postoperative settings.

Performance of multiple neural networks in predicting lower limb joint moments using wearable sensors

Joint moment measurements represent an objective biomechemical parameter in joint health assessment. Inverse dynamics based on 3D motion capture data is the current 'gold standard' to estimate joint moments. Recently, machine learning combined with data measured by wearable technologies such electromyography (EMG), inertial measurement units (IMU), and electrogoniometers (GON) has been used to enable fast, easy, and low-cost measurements of joint moments. This study investigates the ability of various deep neural networks to predict lower limb joint moments merely from IMU sensors. The performance of five different deep neural networks (InceptionTimePlus, eXplainable convolutional neural network (XCM), XCMplus, Recurrent neural network (RNNplus), and Time Series Transformer (TSTPlus)) were tested to predict hip, knee, ankle, and subtalar moments using acceleration and gyroscope measurements of four IMU sensors at the trunk, thigh, shank, and foot. Multiple locomotion modes were considered including level-ground walking, treadmill walking, stair ascent, stair descent, ramp ascent, and ramp descent. We show that XCM can accurately predict lower limb joint moments using data of only four IMUs with RMSE of 0.046 ± 0.013 Nm/kg compared to 0.064 ± 0.003 Nm/kg on average for the other architectures. We found that hip, knee, and ankle joint moments predictions had a comparable RMSE with an average of 0.069 Nm/kg, while subtalar joint moments had the lowest RMSE of 0.033 Nm/kg. The real-time feedback that can be derived from the proposed method can be highly valuable for sports scientists and physiotherapists to gain insights into biomechanics, technique, and form to develop personalized training and rehabilitation programs.

Advances on mechanical designs for assistive ankle-foot orthoses

Assistive ankle-foot orthoses (AAFOs) are powerful solutions to assist or rehabilitate gait on humans. Existing AAFO technologies include passive, quasi-passive, and active principles to provide assistance to the users, and their mechanical configuration and control depend on the eventual support they aim for within the gait pattern. In this research we analyze the state-of-the-art of AAFO and classify the different approaches into clusters, describing their basis and working principles. Additionally, we reviewed the purpose and experimental validation of the devices, providing the reader with a better view of the technology readiness level. Finally, the reviewed designs, limitations, and future steps in the field are summarized and discussed.

Physiotherapeutic Interventions for Individuals Suffering From Plantar Fasciitis: A Systematic Review

The foot and the lower leg comprise the ankle joint complex. The foot is crucial for the maintenance of posture. Frequently, overuse or repeated microtrauma to the fascia causes plantar fasciitis. This review aims to suggest the efficacy of various plantar fasciitis (PF) interventions based on modifications in clinical results. This review included studies from 2019 to March 2023 identified through a systematic literature search. The measures used to predict improvement in pain, discomfort, and foot function symptoms included the Visual Analog scale, Numerical Pain Rating Scale, Pressure Point Threshold by algometer, Weight-Bearing Lunge Test by inch tape, and range of motion. The review included 20 studies that fulfilled the inclusion criteria. Therapeutic interventions included insoles, foot orthosis, foam roller stretching, manual stretching, muscle strengthening, intrinsic muscle activities, extracorporeal shock wave lithotripsy, dry needling, laser, ultrasound, and others, which resulted in pain reduction, improved foot function, and ease of everyday routine. All therapeutic strategies used impacts resulting from minimal to maximal recovery. Various advanced approaches are more effective than conventional physical therapy. In conclusion, conservative therapeutic strategies with manual techniques, orthoses, and alternative intervention strategies can be combined to effectively relieve pain and improve function and overall results. Further high-quality studies are essential to learn more about the ideal dose, treatment approaches, and long-term impacts of these therapies.

The Influence of Knee Extensor and Ankle Plantar Flexor Strength on Single-Leg Standing Balance in Older Women

Impaired balance is a significant risk factor for falls among older adults. The precise impact of lower-extremity muscles, including the proportion of muscle strength, on the performance of single-leg standing balance tests in older individuals is very interesting. The aim of this study is to examine the correlation between the knee extensor (KE), ankle plantar flexor (AP) muscle strength, and performance in single-leg standing balance tests in older females. Additionally, it aims to evaluate the combined proportion of KE and AP muscle strength in maintaining balance during single-leg standing. A total of 90 older females (mean age 67.83 ± 8.00 years) were recruited. All participants underwent maximum voluntary isometric contraction (MVIC) testing of the KE and AP muscles, as well as single-leg standing balance tests with eyes open (SSEO) and eyes closed (SSEC). To examine the influence of KE and AP muscle strength on balance performance, multiple regression analysis was conducted. Low correlations were found between SSEO and MVIC of KE and AP muscles, but moderate correlations were found with percentage of MVIC to body weight ratio (%MVIC/BW). The best model for SSEO included 0.99 times of the %MVIC/BW of AP and 0.66 times that of KE muscles as independent predictor variables (r = 0.682). In conclusion, AP muscle strength was found to have a greater impact on single-leg standing balance compared with KE muscle strength.

Implications of obesity in patients with foot and ankle pathology

Obesity is a growing problem defined as a body mass index of greater than 30 kg/m². It is predicted that by 2030, 48.9% of adults will be classified as obese which expands surgical risk factors to a broad population while increasing healthcare costs at the same time in different socioeconomic groups. This specific population has been widely studied in multiple surgical fields and published studies have shown the implications in each of these fields. The impact of obesity on orthopedic surgical outcomes has been previously reported in several total hip and knee arthroscopy studies, with evidence indicating that obesity is strongly associated with an increased risk of post operative complications together with higher revision rates. In line with increasing interest on the impact of obesity in orthopedics, there has been a similar output of publications in the foot and ankle literature. This review article evaluates several foot and ankle pathologies, their risk factors associated with obesity and subsequent management. It provides an updated, comprehensive analysis of the effects of obesity on foot and ankle surgical outcomes, with the ultimate aim of educating both surgeons and allied health professionals about the risks, benefits, and modifiable factors of operating on obese patients.

Prevalence of Asymptomatic Talar Bone Marrow Edema in Professional Ballet Dancers: Preliminary Data From a 2-Year Prospective Study

Background

Compared with symptomatic bone marrow edema (BME) associated with stress fractures, asymptomatic BME seen on magnetic resonance imaging (MRI) is a phenomenon that has been described in high-level athletes and is thought to be related to bone adaptation to biomechanical loading unique to each sport. However, the prevalence, natural history, and management of these lesions remain poorly understood, particularly in dance, which places tremendous stress on the feet and ankles.

Purposes/Hypothesis

The purposes of this study were to (1) determine the prevalence of asymptomatic BME in the talus before the start of the performance season, (2) identify contributing demographic and training factors, and (3) compare the radiological evidence of talar BME with validated functional foot and ankle scores. We hypothesized that talar BME would be highly prevalent among asymptomatic professional dancers.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 14 professional ballet dancers (6 female and 8 male; mean age, 24 years) were included in this 2-year prospective study. For each participant, we recorded complete medical and surgical history along with scores on the Foot and Ankle Ability Measure (FAAM) and the Foot and Ankle Disability Index. Bilateral foot and ankle 3.0-T MRI scans without contrast were completed before the start of the performance season and were evaluated for BME of the talus using the Fredericson criteria.

Results

Evidence of talar BME was seen in 15 of the 28 (54%) ankles examined and in 9 of 14 (64%) dancers. We found that 6 dancers demonstrated bilateral talar BME, 3 dancers demonstrated unilateral BME, and 5 dancers demonstrated no evidence of BME. The most common location of BME was the posterior talus, seen in 8 of 15 (53%) ankles. No statistically significant differences were noted in dancers with versus those without talar BME with regard to functional scores, demographic characteristics, or weekly training hours.

Conclusion

Asymptomatic talar BME was highly prevalent (64%) in professional ballet dancers and tended to occur posteriorly. Long-term clinical and radiographic follow-up is necessary to determine the natural history of these lesions.