Biomechanics of the ankle

Is Ankle Kinesio Taping Effective to Immediately Change Balance, Range of Motion, and Muscle Strength in Healthy Individuals? A Randomized, Sham-Controlled Trial

Background

The ankle–foot complex plays a key role in maintaining balance because it collects proprioceptive data. Kinesio taping (KT) is a rehabilitative method performed by the cutaneous application of a special elastic tape. The mechanical correction technique of KT was suggested to reposition the joints and alter balance parameters. The aim was to reveal the pure effects of ankle KT on balance, range of motion (ROM), and muscle strength in healthy individuals.

Methods

Forty healthy students were recruited for this randomized, sham-controlled study at a local university. Participants were divided into two groups—experimental and sham application groups. The primary outcome measures were balance parameters. Athlete Single Leg (ASL), Limits of Stability (LoS), and Clinical Test of Sensory Interaction and Balance (CTSIB) were used to measure single-leg dynamic balance, dynamic postural control, and sensory interaction of balance, respectively. Dorsiflexion ROM and dorsiflexor muscle strength were the secondary outcomes.

Results

The ASL score showed significant improvement only in the experimental KT group (P=0.02); however, the LoS score increased significantly in both groups (P<0.05). CTSIB scores, dorsiflexion ROM, and dorsiflexor muscle strength for both ankles did not change in any of the groups after intervention (P>0.05). Moreover, there was no superiority of one intervention over the other in improving any of the variables (P>0.05).

Conclusion

The mechanical correction technique of KT can be useful in providing immediate improvement in single-leg dynamic balance in healthy individuals. However, it may not be effective to significantly change the sensory interaction of balance, dorsiflexion ROM, and muscle strength.

Application of Wearable Sensors in Actuation and Control of Powered Ankle Exoskeletons: A Comprehensive Review

Powered ankle exoskeletons (PAEs) are robotic devices developed for gait assistance, rehabilitation, and augmentation. To fulfil their purposes, PAEs vastly rely heavily on their sensor systems. Human–machine interface sensors collect the biomechanical signals from the human user to inform the higher level of the control hierarchy about the user’s locomotion intention and requirement, whereas machine–machine interface sensors monitor the output of the actuation unit to ensure precise tracking of the high-level control commands via the low-level control scheme. The current article aims to provide a comprehensive review of how wearable sensor technology has contributed to the actuation and control of the PAEs developed over the past two decades. The control schemes and actuation principles employed in the reviewed PAEs, as well as their interaction with the integrated sensor systems, are investigated in this review. Further, the role of wearable sensors in overcoming the main challenges in developing fully autonomous portable PAEs is discussed. Finally, a brief discussion on how the recent technology advancements in wearable sensors, including environment—machine interface sensors, could promote the future generation of fully autonomous portable PAEs is provided.

Multi-segment foot kinematics during gait following ankle arthroplasty

Ankle arthritis is a debilitating disease marked by pain and limited function. Total ankle arthroplasty improves pain while preserving motion and offers an alternative to the traditional treatment of ankle fusion. Gait analysis and functional outcomes tools can provide an objective balanced analysis of ankle replacement for the treatment of ankle arthritis. Twenty-nine patients with end-stage ankle arthritis were evaluated before and after ankle arthroplasty. Multi-segment foot and ankle kinematics were assessed annually following surgery (average 3.5 years, range 1-6 years) using the Milwaukee Foot Model and a Vicon video motion analysis system. Functional outcomes (American Orthopedic Foot and Ankle Society [AOFAS] ankle/hindfoot scale, short form 36 [SF-36] questionnaire) and temporal-spatial parameters were also assessed. Kinematic results were compared to findings from a previously collected group of healthy ambulators. AOFAS and SF-36 mean scores improved postoperatively. Walking speed and stride length increased after surgery. There were significant improvements in tibial sagittal range of motion in terminal stance and hindfoot sagittal range of motion in preswing. Decreased external rotation of the tibia and increased external rotation of the hindfoot were noted throughout the gait cycle. Pain and function improved after ankle replacement as supported by better outcomes scores, increased temporal-spatial parameters, and significant improvement in tibial sagittal range of motion during terminal stance and hindfoot sagittal range of motion during preswing. While multi-segment foot kinematics were improved, they were not restored to control values. Statement of clinical significance: Total ankle arthroplasty does not fully normalize mutli-segment gait kinematics despite improved patient-reported outcomes and gait mechanics.

Relationship between the locomotive syndrome and kinetic and kinematic parameters during static standing and level walking

BACKGROUND

Individuals experiencing age-related decline in locomotor functions are at high-risk of developing locomotive syndrome (LS). LS requires long-term care and greatly influences the quality of life and activities of daily living. The LS risk test was established as a diagnostic criterion by the Japanese Orthopedic Association. Although the relationship between the test and motor function has been established, few studies have reported on the characteristics of LS kinematically and kinetically.

RESEARCH QUESTION

Do elderly with LS show different kinetic and kinematic characteristics compared with healthy elderly during static standing and level walking?

METHODS

Forty-four Participants were divided into an LS group and a non-LS group based on the scores of the LS risk test. The standing posture and walking of the participants were measured using a three-dimensional motion capture system. The results of the groups were compared using an unpaired t-test, and then the characteristics of the LS group were extracted using logistic regression analysis.

RESULTS

LS group exhibited trunk flexion during both standing and gait. A higher intervertebral disc compressive force, which is the index of the low-back mechanical stress, during standing and an increase in ankle plantarflexion angle during walking were observed in LS group.

SIGNIFICANCE

This study determined the kinematic and kinetic features of elderly with LS. The findings suggest that parameters related to the trunk and ankle could be associated with LS. Further studying the characteristics of LS in older adults via motion analysis can help develop prevention and intervention methods for LS.

Joint Preservation Surgery for Varus and Posterior Ankle Arthritis Associated with Flatfoot Deformity

This article introduces novel types of ankle arthritis related to a flatfoot deformity. There has been a long-held belief that severe unmanaged flatfoot deformity leads to valgus ankle arthritis, due to deltoid ligament insufficiency. However, flatfoot deformity can also give rise to varus ankle arthritis as the talus and calcaneus subluxate into opposite directions. Plantarflexion and posterior translation of the talus in the sagittal plane contributes to the eccentric narrowing of the posterior aspect of the tibiotalar joint, which the authors termed posterior ankle arthritis. Subtalar arthrodesis was performed to address the opposing dynamics of the talus and calcaneus, and was combined with a medial longitudinal arch reconstruction in most cases of posterior ankle arthritis and in selected cases of varus ankle arthritis, and satisfactory clinical and radiological results were achieved.

Deciding Between Ankle and Tibiotalocalcaneal Arthrodesis for Isolated Ankle Arthritis

After isolated ankle (tibiotalar) arthrodesis, the triceps progressively shifts the subtalar joint into varus thus blocking compensatory motion from the midtarsal joints. In a tibiotalocalcaneal arthrodesis, the subtalar may be fixed with the correct valgus. Comparison between ankle and tibiotalocalcaneal arthrodesis does not clearly favor one over another for pain relief, satisfaction, and gait analysis. Compensatory sagittal plane motion through the midtarsal joints when the subtalar is fixed in valgus may be responsible for these results. Tibiotalocalcaneal arthrodesis has become our procedure of choice over isolated tibiotalar for end-stage ankle arthritis regardless of the radiographic state of the subtalar.

Control Design for CABLEankle, a Cable Driven Manipulator for Ankle Motion Assistance

A control design is presented for a cable driven parallel manipulator for performing a controlled motion assistance of a human ankle. Requirements are discussed for a portable, comfortable, and light-weight solution of a wearable device with an overall design with low-cost features and user-oriented operation. The control system utilizes various operational and monitoring sensors to drive the system and also obtain continuous feedback during motion to ensure an effective recovery. This control system for CABLEankle device is designed for both active and passive rehabilitation to facilitate the improvement in both joint mobility and surrounding muscle strength.

Recognizing Continuous Multiple Degrees of Freedom Foot Movements with Inertial Sensors

Recognition of continuous foot motions is important in robot-assisted lower limb rehabilitation, especially in prosthesis and exoskeleton design. For instance, perceiving foot motion is essential feedback for the robot controller. However, few studies have focused on perceiving multiple-degree of freedom (DOF) foot movements. This paper proposes a novel human-machine interaction (HMI) recognition wearable system for continuous multiple-DOF ankle-foot movements. The proposed system uses solely kinematic signals from inertial measurement units and multiclass support vector machines by creating error-correcting output codes. We conducted a study with multiple participants to validate the performance of the system using two strategies, a general model and a subject-specific model. The experimental results demonstrated satisfactory performance. The subject-specific approach achieved 98.45% ± 1.17% (mean ± SD) overall accuracy within a prediction time of 10.9 ms ± 1.7 ms, and the general approach achieved 85.3% ± 7.89% overall accuracy within a prediction time of 14.1 ms ± 4.5 ms. The results prove that the proposed system can more effectively recognize multiple continuous DOF foot movements than existing strategies. It can be applied to ankle-foot rehabilitation and fills the HMI high-level control demand for multiple-DOF wearable lower-limb robotics.

A feature-based statistical shape model for geometric analysis of the human talus and development of universal talar prostheses

Statistical data pertaining to anatomic variations of the human talus contain valuable information for advances in biological anthropology, diagnosis of the talar pathologies, and designing talar prostheses. A statistical shape model (SSM) can be a powerful data analysis tool for the anatomic variations of the talus. The main concern in constructing an SSM for the talus is establishing the true geometric correspondence between the talar geometries. The true correspondence complies with biological and/or mathematical homologies on the talar surfaces. In this study, we proposed a semi-automatic approach to establish a dense correspondence between talar surfaces discretized by triangular meshes. Through our approach, homologous salient surface features in the form of crest lines were detected on 49 talar surfaces. Then, the point-wise correspondence information of the crest lines was recruited to create posterior Gaussian process morphable models that non-rigidly registered the talar meshes and consequently established inter-mesh dense correspondence. The resultant correspondence perceptually represented the true correspondence as per our visual assessments. Having established the correspondence, we computed the mean shape using full generalized Procrustes analysis and constructed an SSM by means of principal component analysis. Anatomical variations and the mean shape of the talus were predicted by the SSM. As a clinically related application, we considered the mean shape and investigated the feasibility of designing universal talar prostheses. Our results suggest that the mean shape of (the shapes of) tali can be used as a scalable shape template for designing universal talar prostheses.

Characteristics of Plantar Pressure with Foot Postures and Lower Limb Pain Profiles in Taiwanese College Elite Rugby League Athletes

Background: This study aimed to explore the differences in the distributions of plantar pressure in static and dynamic states and assess the possible pain profiles in the lower limb between elite rugby league athletes and recreational rugby players. Methods: A cross-sectional study of 51 college elite rugby athletes and 57 recreational rugby players was undertaken. The arch index (AI) and plantar pressure distributions (PPDs) with footprint characteristics were evaluated via the JC Mat. Rearfoot alignment was examined to evaluate the static foot posture. The elite group’s lower-limb pain profiles were examined for evaluating the common musculoskeletal pain areas. Results: The recreational group’s AI values fell into the normal range, whereas the elite group’s arch type fell into the category of the low arch. Results from the elite group were: (1) the PPDs mainly exerted on the entire forefoot and lateral midfoot regions in static standing, and transferred to the forefoot region during the midstance phase of walking; (2) the static rearfoot alignment matched the varus posture pattern; (3) the footprint characteristics illustrated the features of low-arched, supinated, dropped metatarsal heads and dropped cuboid feet; and (4) the phalanx and metatarsophalangeal joints, and the abductor hallucis and abductor digiti minimi of the plantar plate were common musculoskeletal pain areas. Conclusions: Characteristics of higher plantar loads beneath forefoot and midfoot associated with low-arched supinated feet in bipedal static stance could be the traceable features for the foot diagram of elite rugby league athletes. The limb pain profiles of the elite rugby league athletes within this study echoed the literature on rugby injuries, and reflected the features of metatarsophalangeal joint pains and dropped cuboids. The relationships among the low-arched supinated feet, metatarsophalangeal joint pains and cuboid syndrome are worth further studies.

The influence of size and comminution of the posterior malleolus fragment on gait in trimalleolar ankle fractures

BACKGROUND

Ankle fractures involving the posterior malleolus generally lead to worse outcome. However, no studies on gait in trimalleolar ankle fractures have evaluated the influence of size and comminution of the posterior malleolar fragment.

METHODS

We expected patients with more severely comminuted posterior malleolus, more severe fracture type and larger posterior fragment to have reduced gait kinematics and poorer patient-reported outcomes. 26 trimalleolar ankle fracture patients were compared with 14 healthy controls and kinematically analyzed using the Oxford Foot Model. Functional outcome was based on 4 patient reported outcome questionnaires. Effects of posterior fragment size, comminution and Haraguchi fracture classification were determined on conventional and 3D CT-scans.

FINDINGS

Trimalleolar patients had lower walking speed and reduced range of motion between the hindfoot and tibia in both loading and push-off phases in the sagittal and transverse planes. The range between the hindfoot and tibia in the sagittal plane in the push-off phase correlated significantly with patient reported outcomes. The absolute and relative surface area of the posterior fragment on conventional CT-scans and 3D CT-scans, correlated significantly with range of motion. Patients with a posterior malleolus size >10% of the posterior malleolus had lower flexion-extension between forefoot and hindfoot during loading phase than patients with a size ≤10%.

INTERPRETATION

Trimalleolar fractures reduce walking speed and range of motion in the talocrural joint. Reduced range in the talocrural joint is associated with poorer outcomes. Posterior fragment size correlated significantly with range of motion in talocrural and midfoot joints and with patient reported outcomes.

LEVEL OF EVIDENCE

Level 3, retrospective study.

Magnetic resonance imaging of ankle disorders in adult Nigerians in Lagos

Objectives:

The aim of this study was to establish the frequency, distribution, and spectrum of abnormalities on ankle magnetic resonance imaging (MRI) in adult Nigerians.

Materials and Methods:

A retrospective analysis of ankle MRI of 50 adult patients was conducted at a single health facility. All adult Nigerians with complete clinical data, MRI images, and radiologists’ reports were included. The clinical history and ankle MRI findings were recorded and analysed. The threshold for statistical significance was established at P≤0.05.

Results:

There were 50 subjects comprising 27 males (54%) and 23 females (46%) aged 25–66 years (mean age = 42.84 ± 9.63 years). The right ankle was evaluated in 27 subjects (54%), while the left ankle was studied in 23 (46%). There was a history of trauma in 40 subjects (80%; 27 right ankles and 13 left ankles). Ankle joint effusion was the most common abnormality—seen in 50% of all subjects and in 62.5% of those with antecedent trauma. Achilles tendinosis and Kager (pre-Achilles) fat pad oedema (8–12%), deltoid ligament tear (8%), and medial malleolar fracture (4%) were the other frequently detected pathologies. The other pathologies detected were posterior tibial tendinosis (2%), plantar fasciopathy (2%), and talar contusion (2%). Joint effusion was significantly more prevalent in post-traumatic ankles than in the non-traumatic ankles and in the right ankles than the left ankles. There was no significant difference in the frequency of ankle abnormalities between the male and female subjects and between subjects younger than and older than the mean age.

Conclusion:

Joint effusion, deltoid ligament tear, and Achilles tendinopathy were the prevalent derangements in evaluated ankle joints. Trauma was the main indication for ankle MRI in this study.

Multiplanar Stiffness of Commercial Carbon Composite Ankle-Foot Orthoses

The mechanical properties of an ankle-foot orthosis (AFO) can impact how a user's movement is either restricted or augmented by the device. However, standardized methods for assessing stiffness properties of AFOs are lacking, posing a challenge for comparing between devices and across vendors. Therefore, the purpose of this study was to quantify the rotational stiffness of thirteen commercial, nonarticulated, carbon composite ankle-foot orthoses. A custom, instrumented test fixture, for evaluating mechanical properties in rotating exoskeletons (EMPIRE), deflected an AFO through 20 deg of plantar/dorsiflexion motion about a specified, but adjustable, ankle axis. Sagittal, frontal, and transverse plane rotational stiffness were calculated, and reliability was assessed between cycles, sessions, and testers. The EMPIRE demonstrated good-to-excellent reliability between testers, sessions, and cycles (intraclass correlation coefficients all ≥0.95 for sagittal plane stiffness measures). Sagittal plane AFO stiffness ranged from 0.58 N·m/deg to 3.66 N·m/deg. AFOs with a lateral strut demonstrated frontal plane stiffnesses up to 0.71 N·m/deg of eversion while those with a medial strut demonstrated frontal plane stiffnesses up to 0.53 N·m/deg of inversion. Transverse plane stiffnesses were less than 0.30 N·m/deg of internal or external rotation. These results directly compare AFOs of different models and from different manufacturers using consistent methodology and are intended as a resource for clinicians in identifying a device with stiffness properties for individual patients.

Investigation of the Relationships Among Clinical Measures of Foot Posture in Individuals with and Without Pronated Foot

BACKGROUND

Many indirect clinical techniques have been developed to assess foot posture; however, there is relatively little research investigating the relationships among these techniques. We investigated the relationships among the most commonly used clinical measures of foot posture-Foot Posture Index-6 (FPI-6), navicular drop (NDP), navicular drift (NDT), and static and dynamic arch indices (SAI and DAI)-in individuals with normal foot posture and those with pronated foot.

METHODS

Sixty-three individuals with FPI-6 scores of 0 to 12 were included. A digital caliper was used to measure NDP and NDT; SAI and DAI were measured by electronic pedobarography. Assessments were applied on the dominant foot. Pearson correlation coefficients were calculated to determine the relationships among measures. Participants were classified into two groups, pronated foot (n = 33) and normal foot posture (n = 30), based on FPI-6 scores, providing a multisegmental and multiplanar assessment. The independent-samples t test was used to compare groups regarding NDP, NDT, SAI, and DAI.

RESULTS

We found a high correlation between NDP and FPI-6 (r = 0.754) and between NDP and NDT (r = 0.778) (all P < .001). A moderate correlation was found between NDT and FPI-6 (r = 0.599) and between DAI and SAI (r = 0.519) (all P < .001). A negligible correlation was found between NDP and DAI (r = 0.268; P = .033). Furthermore, NDP, NDT, and DAI values were higher in individuals with pronated foot compared with those with normal posture (P < .001 for NDP and NDT; P = .022 for DAI), whereas SAI values were not (P = .837).

CONCLUSIONS

These results suggest that there are moderate-to-strong relationships among FPI-6, NDP, and NDT and between SAI and DAI. The NDP, NDT, and DAI are suitable for the classification of foot posture based on FPI-6 scores. This study can guide clinicians and researchers to associate the foot posture measures with each other.

Effects of restriction of forefoot rocker functions by immobilisation of metatarsophalangeal joints on kinematics and kinetics during walking

OBJECTIVE

This study was conducted to investigate the effects of restriction of forefoot rocker (FFR) functions by immobilisation of unilateral metatarsophalangeal joints (MPJs) on kinematic and kinetic factors during walking.

METHODS

Eighteen healthy young adults participated in this study. To immobilise the MPJs of the right leg, an aluminium sole plate (AS) was fixed on the sole of the foot. Kinematic and kinetic data were collected while each subject walked at a comfortable speed with the AS and without.

RESULTS

In the AS condition, the walking speed and contralateral step length were significantly decreased, and an asymmetrical centre of mass (COM) movement was observed. The range of plantarflexion motion and positive work by the ankle joint were decreased markedly during the late stance of the AS limb. In contrast, maximum hip and knee flexion angles in the swing phase of the AS limb and positive work by the bilateral hip joints over the gait cycle were increased.

CONCLUSIONS

The results suggested that MPJ immobilisation may result in marked motion limitation of ankle plantarflexion and inhibition of push-off by the ankle joint despite no restrictions on the ankle joint. These changes may interfere with gait speed and a smooth and symmetrical COM shift during walking.

Weightbearing Radiography and MRI Findings in Ankle Fractures

Background. Static weightbearing radiography can be used to assess stability in ankle fractures by measuring lateral talar shift (medial clear space; MCS). However, the correlation of a stable ankle joint under weightbearing load and the structural integrity of the deltoid ligament has not been shown. In this study, we assessed deltoid ligament integrity on magnetic resonance imaging (MRI) and correlated that with weightbearing and gravity stress test radiography. Methods. Thirty-four patients with supination external rotation II-IV (SER) fractures underwent MRI, weightbearing radiography, and gravity stress test. On MRI, the deep anterior and posterior tibiotalar deltoid, tibionavicular and tibiocalcaneal ligaments, as well as the syndesmosis were assessed as intact, partial rupture, or complete rupture. The MCS was measured as the distance between the lateral border of the medial malleolus and the medial border of the talus at the level of the talar dome on the mortise view. Results. Twenty-three patients suffered a deep anterior tibiotalar ligament rupture (16 partial; 7 complete) and 2 a deep posterior tibiotalar ligament tear (1 partial; 1 complete). For MCS on weightbearing radiography, no statistically significant differences were identified between any of the individual groups. With gravity stress radiography, only a complete tear of the tibiocalcaneal ligament showed a significantly higher MCS than a partial tear or intact tibiocalcaneal ligament (P < .005). No other ligament disruption showed a significant difference between the complete rupture versus intact or partial tear. Conclusion. Weightbearing radiography does not show much variation in terms of MCS even with ligamentous disruption and fibula fracture. The talus often centers itself underneath the tibia with weightbearing radiography.Levels of Evidence: Level III: Retrospective cohort study.

An Uncommon Complication of Ankle Varus During Tibial Transport in an Ilizarov Frame: A Case Report

CASE

We treated a 22-year-old man with an infected fracture of the tibia by resection of necrosed bone and bone transport with an Ilizarov device. Four weeks after initiation of transport, an ankle varus deformity from distal migration of the fibula was noticed. A wire that had been incorrectly placed through both the fibula and the transport fragment of the tibia was identified as responsible for this complication. It was changed after an acute reversal of the transport.

CONCLUSION

Errors in the surgical technique during the insertion of Ilizarov wires can result in unusual complications. Attention to details is a must to avoid them.

Development and Evaluation of a Prosthetic Ankle Emulator With an Artificial Soleus and Gastrocnemius

In individuals with transtibial limb loss, a contributing factor to mobility-related challenges is the disruption of biological calf muscle function due to transection of the soleus and gastrocnemius. Powered prosthetic ankles can restore primary function of the mono-articular soleus muscle, which contributes to ankle plantarflexion. In effect, a powered ankle acts like an artificial soleus (AS). However, the biarticular gastrocnemius connection that simultaneously contributes to ankle plantarflexion and knee flexion torques remains missing, and there are currently no commercially available prosthetic ankles that incorporate an artificial gastrocnemius (AG). The goal of this work is to describe the design of a novel emulator capable of independently controlling artificial soleus and gastrocnemius behaviors for transtibial prosthesis users during walking. To evaluate the emulator's efficacy in controlling the artificial gastrocnemius behaviors, a case series walking study was conducted with four transtibial prosthesis users. Data from this case series showed that the emulator exhibits low resistance to the user's leg swing, low hysteresis during passive spring emulation, and accurate force tracking for a range of artificial soleus and gastrocnemius behaviors. The emulator presented in this paper is versatile and can facilitate experiments studying the effects of various artificial soleus and gastrocnemius dynamics on gait or other movement tasks. Using this system, it is possible to address existing knowledge gaps and explore a wide range of artificial soleus and gastrocnemius behaviors during gait and potentially other activities of daily living.

Determining the relationship between the impairment of selective voluntary motor control and gait deviations in children with cerebral palsy using simple video-based analyses

BACKGROUND

The impairment of selective voluntary motor control (SVMC) in children with cerebral palsy (CP) has been shown to correlate with their gait characteristics using complex 3D gait analysis systems (3DGA); however, this relationship has not been investigated using simple video-based observational gait analysis (VBOGA). The aim of this study was to determine the relationship between VBOGA and SVMC of the lower extremities in children with CP.

METHODS

Forty-two CP children 10.9 ± 5.7 years old with Gross Motor Function Classification System (GMFCS) levels I-III participated in the study. Their gait characteristics were assessed using the Edinburgh Visual Gait Score (EVGS), and selective voluntary motor control was tested using the Selective Control Assessment of the Lower Extremity (SCALE). Spearman's rho correlation test with Cohen's classification were used in the statistical analyses.

RESULTS

The GMFCS levels (r = 0.604, p < 0.001), foot clearance (r = -0.584. p < 0.001), and maximum ankle dorsiflexion (r =-0.567, p < 0.001) during the swing phase had strong correlations with total SCALE scores. There was also a moderate correlation between total SCALE scores and total EVGS (r =-0.494, p < 0.001), knee extension in the terminal swing phase (r = -0.353, p < 0.001), peak sagittal trunk position (r = -0.316, p < 0.005), and maximum lateral shift (r = -0.37, p < 0.001).

CONCLUSION

Impaired lower extremity SVMC was noticeably related to the foot and ankle movements in the swing phase and initial stance during walking as well as the total EVGS scores and sagittal and frontal trunk movements. The SCALE correlations with VBOGA were similar those observed in the complex 3DGA in the literature; therefore, we suggest that SVMC impairment of gait could be evaluated using simple VBOGA. These findings may help to tailor physical therapy programs for CP children to increase their motor control and walking quality.

Joint Angle, Range of Motion, Force, and Moment Assessment: Responses of the Lower Limb to Ankle Plantarflexion and Dorsiflexion

There is limited research on the biomechanical assessment of the lower limb joints in relation to dynamic movements that occur at the hip, knee, and ankle joints when performing dorsiflexion (DF) and plantarflexion (PF) among males and females. This study investigated the differences in joint angles (including range of motion (ROM)) and forces (including moments) between the left and right limbs at the ankle, knee, and hip joints during dynamic DF and PF movements in both males and females. Using a general linear model employing multivariate analysis in relation to the joint angle, ROM, force, and moment datasets, the results revealed significant main effects for gender, sidedness, phases, and foot position with respect to joint angles. Weak correlations were observed between measured biomechanical variables. These results provide insightful information for clinicians and biomechanists that relate to lower limb exercise interventions and modelling efficacy standpoints.

Current management of trimalleolar ankle fractures

A trimalleolar ankle fracture is considered unstable and treatment is generally performed operatively. Computed tomography is important for the operative planning by providing an elaborated view of the posterior malleolus.

Trimalleolar ankle fractures have a rising incidence in the last decade with up to 40 per 100,000 people per year. With a growing number of elderly patients, trimalleolar ankle injuries will become more relevant in the form of fragility fractures, posing a particular challenge for trauma surgeons.

In patients with osteoporotic trimalleolar ankle fractures and relevant concomitant conditions, further evidence is awaited to specify indications for open reduction and internal fixation or primary transfixation of the ankle joint.

In younger, more demanding patients, arthroscopic-assisted surgery might improve the outcome, but future research is required to identify patients who will benefit from assisted surgical care.

This review considers current scientific findings regarding all three malleoli to understand the complexity of trimalleolar ankle injuries and provide the reader with an overview of treatment strategies and research, as well as future perspectives.

Cite this article: EFORT Open Rev 2021;6:692-703. DOI: 10.1302/2058-5241.6.200138

Correlation of stress radiographs to injuries associated with lateral ankle instability

BACKGROUND

Stress radiographs have demonstrated superior efficacy in the evaluation of ankle instability.

AIM

To determine if there is a degree of instability evidenced by stress radiographs that is associated with pathology concomitant with ankle ligamentous instability.

METHODS

A retrospective review of 87 consecutive patients aged 18-74 who had stress radiographs performed at a single institution between 2014 and 2020 was performed. These manual radiographic stress views were then correlated with magnetic resonance imaging and operative findings.

RESULTS

A statistically significant association was determined for the mean and median stress radiographic values and the presence of peroneal pathology (P = 0.008 for tendonitis and P = 0.020 for peroneal tendon tears). A significant inverse relationship was found between the presence of an osteochondral defect and increasing degrees of instability (P = 0.043).

CONCLUSION

Although valuable in the clinical evaluation of ankle instability, stress radiographs are not an independent predictor of conditions associated with ankle instability.

Mind your step: predicting maximum ankle inversion during cutting movements in soccer

The objective of this investigation was to identify parameters at initial contact that would predict the subsequent maximum ankle inversion angle during cutting movements. We conducted a secondary data analysis and calculated kinematics of 1,400 cuttings performed by 46 male soccer athletes. The movement task consisted of an approach run, followed by a pre-planned cutting movement. A linear mixed regression model was applied to predict the maximum ankle inversion angle during the first 100 ms of ground contact. The prediction was made based on six predictors that describe change-of-direction intensity and foot placement as found to be relevant in the literature. The model explained 62% of the variance of maximum ankle inversion angles. A change of the main predictors (foot rotation, cutting angle and initial ankle inversion) by 1 SD caused a reduction of the subsequent maximum ankle inversion angle by 2.6-4.4°. Regarding the intensity of a change-of-direction movement, cutting angle seems to have a higher influence on maximum ankle inversion angle than approach velocity. With respect to the individual foot positioning, the maximum ankle inversion angle can be reduced by increasing exorotation and eversion of the foot while shifting towards forefoot landing.

Load to Failure of the Ankle Joint Complex After Fusion of the Subtalar and Talonavicular Joints: A Cadaveric Study

Recent literature has proposed that restriction of joints in the rearfoot secondary to coalitions may lead to increased risk for severe ankle fracture after trauma. There is a paucity of literature regarding the rigidity of the ankle joint after arthrodesis of the subtalar and talonavicular joints. In this study, load-to-failure testing of cadaveric ankle joints with and without fusion of the subtalar and talonavicular joints was performed to determine if clinically relevant fracture patterns could be reproduced. Of the 3 fixation patterns studied, combined subtalar and talonavicular joint fusion resulted in a measurable increase in joint stiffness; however, this was not statistically significant. Clinical and radiographic examination postloading revealed that all tested ankle joints sustained a dislocation type injury rather than a specific bone fracture pattern. It was determined that a pure low-speed bending and compression model does not produce clinically relevant fracture patterns, and that higher energy mechanisms are required.

Distal Fibula Reconstruction in Primary Malignant Tumours

(1) Background: Restoration of ankle biomechanics after distal fibula (DF) resection in bone sarcomas can be performed with different techniques. We report the functional and oncological outcomes of a case series; (2) Methods: Ten patients (5 females and 5 males) with a mean age of 27 years (range 10-71) were retrospectively evaluated. Following the resection, different techniques were used to reconstruct the ankle: tibiotalar arthrodesis, residual lateral malleolus fixed to the tibia, non-vascularized or rotational vascularized fibula transposition and intercalary allograft. All complications were recorded, and the functional outcomes were evaluated; (3) Results: The mean follow-up time was 54 months (range, 13-116). Six patients were free of disease while four patients died of disease. All patients had a stable ankle and bone union, which was achieved after a mean of 9.4 months (range 3-20). The mean MSTS Score was 26.7 (range 21-30). Chronic ankle pain and peroneal external nerve palsy were observed. Patients underwent additional surgeries for deep infection and for equinus ankle deformity. No local recurrence was observed. Metastasis occurred in four patients after a mean of 14.7 months (range 2-34); (4) Conclusions: After DF resection, the restoration of ankle biomechanics gives acceptable functional results, but a larger series of patients with long-time follow-up are required to confirm the durability of the reconstruction.

In Silico Finite Element Analysis of the Foot Ankle Complex Biomechanics: A Literature Review

Computational approaches, especially finite element analysis (FEA), have been rapidly growing in both academia and industry during the last few decades. FEA serves as a powerful and efficient approach for simulating real-life experiments, including industrial product development, machine design, and biomedical research, particularly in biomechanics and biomaterials. Accordingly, FEA has been a "go-to" high biofidelic software tool to simulate and quantify the biomechanics of the foot-ankle complex, as well as to predict the risk of foot and ankle injuries, which are one of the most common musculoskeletal injuries among physically active individuals. This paper provides a review of the in silico FEA of the foot-ankle complex. First, a brief history of computational modeling methods and finite element (FE) simulations for foot-ankle models is introduced. Second, a general approach to build an FE foot and ankle model is presented, including a detailed procedure to accurately construct, calibrate, verify, and validate an FE model in its appropriate simulation environment. Third, current applications, as well as future improvements of the foot and ankle FE models, especially in the biomedical field, are discussed. Finally, a conclusion is made on the efficiency and development of FEA as a computational approach in investigating the biomechanics of the foot-ankle complex. Overall, this review integrates insightful information for biomedical engineers, medical professionals, and researchers to conduct more accurate research on the foot-ankle FE models in the future.

Total ankle replacement along with subtalar joint arthrodesis: In-vitro and in-silico biomechanical investigations

Total ankle replacement (TAR) and subtalar joint (STJ) fusion, are popular treatments for ankle osteoarthritis (OA). Short endurance limits the former, and movement disability comes with the latter. It is hypothesized here that fusion of the STJ can improve the longevity of the TAR prosthesis. In this study, a fresh human cadaver's ankle joint underwent TAR surgery, and strain patterns in the vicinity of prosthesis were recorded after the application of axial compressive load on tibia, resembling stance phase of the gait. Then, STJ of the same sample fused (FTAR), and a similar test procedure was pursued. The obtained strains in the FTAR were smaller than those of the TAR (p < .01). Finite element models of the tested samples were also made, and validated by experimental strains. The validated FE models were then employed to find stress distribution on the tibial plateau and prosthesis compartments. FTAR demonstrated more regular stress profiles in bone-prosthesis interface. Also, maximum von Mises stress in the talar component of the FTAR is approximately half of that in the TAR (8 and 15 MPa, respectively). Based on the results of this study, having a more symmetric load distribution on the prosthesis after STJ fusion, longevity of the TAR may likely increase.

Foot Muscle Strengthening and Lower Limb Injury Prevention

Background and objectives: The active and passive structures of the foot act in unison to not only be compliant enough to assist in ground reaction force attenuation but also resist deformation to provide a stable base of support. A foot that is unable to adjust to the imposed demands during high-intensity sporting activities may alter the moments and forces acting on the joints, increasing the risk of non-contact anterior cruciate ligament ruptures (ACLR) and lateral ankle sprains (LAS). Prophylactic strengthening programs are often used to reduce the risk of these injuries, but at present, very few prophylactic programs include foot-specific strengthening strategies. The aim of this theoretical review is to ascertain the prophylactic role strengthening muscles acting on the foot may have on ACLR and LAS injury risk. Methods: Literature relating to risk factors associated with ACLR and LAS injury and the anatomy and biomechanics of normal foot function was searched. In addition, ACLR and LAS injury prevention programs were also sought. A theoretical, narrative approach was followed to synthesize the information gathered from the articles. Results: The foot segments are governed by the congruity of the articulations and the activity of the foot muscles. As such, there is a coupling effect between shank, calcaneus, midfoot, and hallux movement which play a role in both ACLR and LAS injury risk. Conclusions: Strengthening the muscles acting on the foot may have a significant impact on ACLR and LAS injury risk.

Three-Dimensional Finite Element Analysis and Biomechanical Analysis of Midfoot von Mises Stress Levels in Flatfoot, Clubfoot, and Lisfranc Joint Injury

Background

Midfoot deformity and injury can affect the internal pressure distribution of the foot. This study aimed to use 3D finite element and biomechanical analyses of midfoot von Mises stress levels in flatfoot, clubfoot, and Lisfranc joint injury.

Material/Methods

Normal feet, flatfeet, clubfeet (30 individuals each), and Lisfranc injuries (50 individuals) were reconstructed by CT, and 3D finite element models were established by ABAQUS. Spring element was used to simulate the plantar fascia and ligaments and set hyperelastic coefficients in encapsulated bone and ligaments. The stance phase was simulated by applying 350 N on the top of the talus. The von Mises stress of the feet and ankle was visualized and analyzed.

Results

The von Mises stress on healthy feet was higher in the lateral metatarsal and ankle bones than in the medial metatarsal bone. Among the flatfoot group, the stress on the metatarsals, talus, and navicular bones was significantly increased compared with that on healthy feet. Among patients with clubfeet, stress was mainly concentrated on the talus, and stress on the lateral metatarsal and navicular bones was significantly lower. The von Mises stress on the fractured bone was decreased, and the stress on the bone adjacent to the fractured bone was higher in Lisfranc injury. During bone dislocation alone or fracture accompanied by dislocation, the von Mises stress of the dislocated bone tended to be constant or increased.

Conclusions

Prediction of von Mises stress distribution may be used clinically to evaluate the effects of deformity and injury on changes in structure and internal pressure distribution on the midfoot.

Quantitative measurements of haemophilic joint tissues by point-of-care musculoskeletal ultrasound: Associations with clinical and functional joint outcome parameters

Background

Painful arthropathy is a long‐term complication in patients with hemophilia (PWH), affecting mobility and quality of life. A major barrier for the appraisal of joint health is the absence of point‐of‐care (POC) imaging modalities to promptly identify and manage arthropathic changes. Accordingly, we developed the Joint tissue Activity and Damage Exam (JADE) POC musculoskeletal ultrasound (MSKUS) protocol. JADE is validated for haemophilic joint tissue recognition with high intra/inter‐rater and inter‐operator reliability.

Aims

Evaluate associations of JADE with clinical (Hemophilia Joint Health Score, [HJHS]) and functional (total arc [combined flexion and extension range of motion [ROM]]) parameters.

Methodology

In this multi‐centre prospective study, we recruited PWH A or B with at least one arthropathic joint. We evaluated joint health (both elbows, knees, and ankles) by comparing JADE measurements (soft tissue and cartilage thickness, and osteochondral alterations) with HJHS and total arc.

Results

Of 44 PWH, most had hemophilia A (35/44), were severe (36/44) and had a median age of 36 years. Increasing HJHSs and declining total arc, indicating worsening arthropathy, were associated with JADE measurements in the expected direction, including (1) increasing length of osteochondral alterations, (2) diminished cartilage thickness, and (3) greater soft tissue expansion. The ankles had the highest proportion of joints without measurable (missing) cartilage. In multivariable models MSKUS measurements explained 68% and 71% of the variation in HJHS and total arc respectively for the elbow, 55% and 29% respectively for the knee, and 50% and 73% for the ankle.

Conclusions

This study highlights the associations of direct intra‐articular ultrasonography measurements using the JADE protocol with clinical and functional parameters. Our findings underscore the clinical value of POC MSKUS using the JADE protocol as a complementary instrument for the diagnosis and management of haemophilic arthropathy.

Dual-Motor-Task of Catching and Throwing a Ball During Overground Walking in Virtual Reality

Virtual Reality is a versatile platform to study human behavior in simulated environments and to develop interventions for functional rehabilitation. In this work, we designed a dual-task paradigm in a virtual environment where both tasks demand motor skills. Twenty-one healthy adults (mean age: 24.1 years) participated in this study. The experiment involved three conditions - normal overground walking, catch and throw a ball while standing, and catch and throw a ball while walking overground -all in the virtual environment. We investigated the dual-task gait characteristics and their correlations with outcomes from cognitive assessments. Results show that subjects walk conservatively with smaller stride lengths, larger stride widths and stride time while catching and throwing. However, they are able to throw the balls more accurately at the target and achieve higher scores. During the dual-task throw, we observed that the participants threw more balls during the stance phase of the gait when the foot was in the terminal stance and pre-swing region. During this region, the body has forward momentum. In addition, the changes in gait characteristics during dual-task throw correlate well with outcome measures in standardized cognitive tests. This study provides a new and engaging paradigm to analyze dual-motor-task cost in a virtual reality environment and it can be used as a basis to compare strategies adopted by different population groups with healthy young adults to execute coordinated motor tasks.

Strain patterns in normal anterior talofibular and calcaneofibular ligaments and after anatomical reconstruction using gracilis tendon grafts: A cadaver study

Background

Inversion ankle sprains, or lateral ankle sprains, often result in symptomatic lateral ankle instability, and some patients need lateral ankle ligament reconstruction to reduce pain, improve function, and prevent subsequent injuries. Although anatomically reconstructed ligaments should behave in a biomechanically normal manner, previous studies have not measured the strain patterns of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) after anatomical reconstruction. This study aimed to measure the strain patterns of normal and reconstructed ATFL and CFLs using the miniaturization ligament performance probe (MLPP) system.

Methods

The MLPP was sutured into the ligamentous bands of the ATFLs and CTLs of three freshly frozen cadaveric lower-extremity specimens. Each ankle was manually moved from 15° dorsiflexion to 30° plantar flexion, and a 1.2-N m force was applied to the ankle and subtalar joint complex.

Results

The normal and reconstructed ATFLs exhibited maximal strain (100) during supination in three-dimensional motion. Although the normal ATFLs were not strained during pronation, the reconstructed ATFLs demonstrated relative strain values of 16–36. During the axial motion, the normal ATFLs started to gradually tense at 0° plantar flexion, with the strain increasing as the plantar flexion angle increased, to a maximal value (100) at 30° plantar flexion; the reconstructed ATFLs showed similar strain patterns. Further, the normal CFLs exhibited maximal strain (100) during plantar flexion-abduction and relative strain values of 30–52 during dorsiflexion in three-dimensional motion. The reconstructed CFLs exhibited the most strain during dorsiflexion-adduction and demonstrated relative strain values of 29–62 during plantar flexion-abduction. During the axial motion, the normal CFLs started to gradually tense at 20° plantar flexion and 5° dorsiflexion.

Conclusion

Our results showed that the strain patterns of reconstructed ATFLs and CFLs are not similar to those of normal ATFLs and CFLs.

What Does the Body Communicate With Postural Oscillations? A Clinical Investigation Hypothesis

The evolution of the foot and the attainment of the bipedia represent a distinctive characteristic of the human species. The force of gravity is dissipated through the tibial astragalic joints, and the movement of the ankle is manifested on a sagittal plane. However, this is in contrast with other studies that analyze the straight station in bipodalic support of the body. According to these studies, the oscillations of the body dissipated by the articulation of the ankle are greater on a frontal plane than on a sagittal plane. Probably, this can be deduced by analyzing the concept of "cone of economy (COE) and equilibrium;" a cone that has its base with the oscillations described by the 360° movement performed by the head and has its apex that supports polygon defined by the tibio-astragalic articulation. The purpose of this study was to evaluate a kind of communication between the oscillations of the COE and equilibrium and the main sphere of somatic dysfunction (structural, visceral, or cranial sacral), assessing the reliability of the "fascial compression test." The implications of this connection have been considered, while grounding the hypothesis in the ability of the human body to maintain its center of mass (COM) with minimum energy expenditure and with minimum postural influence. At the same time, the fascial compression test provides a dominant direction of fascial compartments in restriction of mobility.

Clinical Use of Talar Prostheses

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The blood supply to the talus is vulnerable to damage, making the talus susceptible to osteonecrosis, with limited treatment options.

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Talar bone replacement has been investigated as a treatment option to preserve ankle function and maintain limb length.

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Successful talar bone replacements have been performed for the past >35 years, with variations in design, methods of fixation, materials, and manufacturing techniques.

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The designs of talar prostheses range from custom-made partial (talar body) or total prostheses to prefabricated universal (non-custom-made) prostheses.

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Total talar prostheses have been demonstrated to function better than partial talar prostheses; however, there is a need for long-term studies regarding custom-made total talar prostheses and prefabricated universal talar prostheses in order to determine their long-term effectiveness.

Effect of Ankle Torque on the Ankle-Foot Orthosis Joint Design Sustainability

The ankle joint of a powered ankle–foot orthosis (PAFO) is a prominent component, as it must withstand the dynamic loading conditions during its service time, while delivering all the functional requirements such as reducing the metabolic effort during walking, minimizing the stress on the user’s joint, and improving the gait stability of the impaired subjects. More often, the life of an AFO is limited by the performance of its joint; hence, a careful design consideration and material selection are required to increase the AFO’s service life. In the present work, a compact AFO joint was designed based on a worm gear mechanism with steel and brass counterparts due to the fact of its large torque transfer capability in a single stage, enabling a compact joint. Further, it provided an added advantage of self-locking due to the large friction that prevents backdrive, which is beneficial for drop-foot recovery. The design was verified using nonlinear finite element analysis for maximum torque situations at the ankle joint during normal walking. The results indicate stress levels within its design performance; however, it is recommended to select high-grade structural steel for the ankle shaft as the highest stresses in AFO were located on it.

A review of the role of lower-leg strength measurements in ankle sprain and chronic ankle instability populations

Lower-leg strength training has been a cornerstone of ankle sprain and chronic ankle instability (CAI) rehabilitation and an important consideration for return-to-play in athletes with ankle injuries. The purpose of this literature review is to offer a contemporary, evidence-based overview of the role of ankle strength measurements as they relate to acute ankle sprain rehabilitation and those who have developed CAI. A comprehensive 20-year scan of the relevant research was conducted to assist us in providing this important update for clinicians and biomechanists working with patients and subjects with acute and chronic ankle sprains. While variability exists with measurement devices and methodology, strength assessment remains a critical component of ankle sprain and CAI treatment schemes. Helpful tips on obtaining and processing the most accurate strength assessments for lower-leg musculature are presented.

An Analytical Insight Into How Walking Speed and Spatial and Temporal Symmetry Are Related to Ankle Dysfunctions in Children With Hemiplegic Cerebral Palsy

OBJECTIVE

The aim of the study was to identify the major determining factors among ankle dysfunctions for walking speed and symmetry in children with hemiplegic cerebral palsy.

DESIGN

This was a prospective analysis that included 52 children with hemiplegic cerebral palsy, aged between 5 and 8 yrs, had mild spasticity, and were functioning at Gross Motor Function Classification System level I or II. The dorsiflexor and plantar flexor strength, dynamic spasticity (represented by gastrocnemius muscle lengthening velocity during stance phase), plantar flexors stiffness, ankle joint position sense, and walking performance (spatiotemporal parameter) were assessed.

RESULTS

The least absolute shrinkage and selection operator regression analyses showed that the dorsiflexor strength of the paretic limb was the major determining factor of walking speed (R2 = 0.38, P < 0.001). Dynamic spasticity of the plantar flexors explained a portion of the variance in walking speed (R2 = 0.15, P < 0.001) and the highest portion of the variance in spatial walking symmetry (R2 = 0.18, P = 0.002). In addition, the ankle joint position sense was the primary determinant of temporal walking symmetry (R2 = 0.10, P = 0.021).

CONCLUSIONS

In children with hemiplegic cerebral palsy, walking speed is mostly influenced by dorsiflexor muscle strength, temporal walking symmetry is associated with the joint position sense, whereas spatial walking symmetry is explicated by the dynamic spasticity of the plantar flexor muscles.

Ankle arthritis - an important signpost in rheumatologic practice

Ankle arthritis is a useful clinical signpost to differential diagnosis in rheumatic disease. Biomechanical features and differences in cartilage physiology compared with the knee may confer protection of the ankle joint from factors predisposing to certain arthritides. The prevalence of ankle OA is low, and usually secondary to trauma. Primary OA of the ankle should be investigated for underlying causes, especially haemochromatosis. New presentations of inflammatory mono/oligo arthritis involving the ankle are more likely due to undifferentiated arthritis or spondyloarthritis than RA, and gout over CPPD. The ankle is often involved in bacterial and viral causes of septic arthritis, especially bacterial, chikungunya and HIV infection, but rarely tuberculosis. Periarticular hind foot swelling can be confused with ankle arthritis, exemplified by Lofgren’s syndrome and hypertrophic osteoarthropathy where swelling is due to subcutaneous oedema and osteitis respectively, and the ankle joint is rarely involved.

Impact of a dynamic ankle orthosis on acute pain and function in patients with mechanical foot and ankle pain

BACKGROUND

Over two million Americans visit the doctor each year for foot and ankle pain stemming from a degenerative condition or injury. Ankle-foot orthoses can effectively manage symptoms, but traditional designs have limitations. This study investigates the acute impact of a novel "dynamic ankle-foot orthosis" ("orthosis") in populations with mechanical pain (from motion or weight-bearing).

METHODS

With and without the brace, participants (n = 25) performed standing, over-ground level walking, treadmill level walking, stair ascent, stair descent, single leg hold, squat, and sitting. Instrumented insoles captured in-shoe vertical forces and a visual analog scale was used to assess pain levels during each activity. Subsequently, the self-perceived impact of the orthosis on the patient's symptoms and function was ranked on a scale from -10 (most worsened) to +10 (most improved).

FINDINGS

Peak in-shoe force was reduced during level and stair walking (P < 0.05). Average perceived pain was 1.2 to 1.6 points lower in the orthosis than the unbraced control for the active tasks. The majority of participants reported that the brace improved their symptoms (n = 19), while a smaller group reported that the brace did not affect their symptoms (n = 5), although average function scores were improved for both groups (+2.4 to +4.5). The group of individuals with improved symptoms included cases of osteoarthritis, tendon dysfunction, chronic pain, sprains, and nerve disorders.

INTERPRETATION

The orthosis effectively improved pain symptoms and improved the ability of impaired individuals to complete functional activities of daily living such as level walking and stair walking.

Reliability of a close-range photogrammetry technique to measure ankle kinematics during active range of motion in place

BACKGROUND

As the risk of ankle turn during daily activity is very high, studying ankle kinematics in place is important for ankle sprain prevention. The close-range photogrammetry (CRP) technique is used to measure ankle kinematics during active range of motion (AROM) in place. The purpose of the study was to assess the reliability of CRP to measure ankle kinematics.

METHODS

Twenty adults were recruited and fourteen retro-reflective targets were mounted on the skin of their right feet. Imaging sensors were self-calibrated using a bundle adjustment technique, and the images were downloaded with Australis photogrammetric software. Three trials were conducted and reliability coefficients were used to assess agreement between them.

RESULTS

Reliability was almost perfect and the results show that the intraclass correlation coefficient (ICC) of ankle angle values were (dorsiflexion = 0.96), (plantarflexion = 0.81), (inversion = 0.92), (eversion = 0.95), (internal rotation = 0.92), and (external rotation = 0.78). The overall intraclass correlation coefficient was 0.89 and the standard error of the measurement (SEM) values ranged from (0.37° to 6.18°).

CONCLUSIONS

The results indicate that the CRP technique was able to reliably measure ankle kinematics. The results may support and enhance knowledge related to ankle AROM in the clinical arena.

Restoration of bilateral motor coordination from preserved agonist-antagonist coupling in amputation musculature

Background

Neuroprosthetic devices controlled by persons with standard limb amputation often lack the dexterity of the physiological limb due to limitations of both the user’s ability to output accurate control signals and the control system’s ability to formulate dynamic trajectories from those signals. To restore full limb functionality to persons with amputation, it is necessary to first deduce and quantify the motor performance of the missing limbs, then meet these performance requirements through direct, volitional control of neuroprosthetic devices.

Methods

We develop a neuromuscular modeling and optimization paradigm for the agonist-antagonist myoneural interface, a novel tissue architecture and neural interface for the control of myoelectric prostheses, that enables it to generate virtual joint trajectories coordinated with an intact biological joint at full physiologically-relevant movement bandwidth. In this investigation, a baseline of performance is first established in a population of non-amputee control subjects (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$n = 8$$\end{document}n=8). Then, a neuromuscular modeling and optimization technique is advanced that allows unilateral AMI amputation subjects (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$n = 5$$\end{document}n=5) and standard amputation subjects (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$n = 4$$\end{document}n=4) to generate virtual subtalar prosthetic joint kinematics using measured surface electromyography (sEMG) signals generated by musculature within the affected leg residuum.

Results

Using their optimized neuromuscular subtalar models under blindfolded conditions with only proprioceptive feedback, AMI amputation subjects demonstrate bilateral subtalar coordination accuracy not significantly different from that of the non-amputee control group (Kolmogorov-Smirnov test, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P \ge 0.052$$\end{document}P≥0.052) while standard amputation subjects demonstrate significantly poorer performance (Kolmogorov-Smirnov test, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P < 0.001$$\end{document}P<0.001).

Conclusions

These results suggest that the absence of an intact biological joint does not necessarily remove the ability to produce neurophysical signals with sufficient information to reconstruct physiological movements. Further, the seamless manner in which virtual and intact biological joints are shown to coordinate reinforces the theory that desired movement trajectories are mentally formulated in an abstract task space which does not depend on physical limb configurations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00829-z.

Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network

Lower limb exoskeleton robots help with walking movements through mechanical force, by identifying the wearer’s walking intention. When the exoskeleton robot is lightweight and comfortable to wear, the stability of walking increases, and energy can be used efficiently. However, because it is difficult to implement the complex anatomical movements of the human body, most are designed simply. Due to this, misalignment between the human and robot movement causes the wearer to feel uncomfortable, and the stability of walking is reduced. In this paper, we developed a two degrees of freedom (2DoF) ankle exoskeleton robot with a subtalar joint and a talocrural joint, applying a four-bar linkage to realize the anatomical movement of a simple 1DoF structure mainly used for ankles. However, bidirectional tendon-driven actuators (BTDAs) do not consider the difference in a length change of both cables due to dorsiflexion (DF) and plantar flexion (PF) during walking, causing misalignment. To solve this problem, a BTDA was developed by considering the length change of both cables. Cable-driven actuators and exoskeleton robot systems create uncertainty. Accordingly, adaptive control was performed with a proportional-integral-differential neural network (PIDNN) controller to minimize system uncertainty.

The effect of changing mediolateral center of pressure on rearfoot eversion during treadmill running

INTRODUCTION

Atypical rearfoot eversion is an important kinematic risk factor in running-related injuries. Prominent interventions for atypical rearfoot eversion include foot orthoses, footwear, and taping, yet a running gait retraining is lacking. Therefore, the aim was to investigate the effects of changing mediolateral center of pressure (COP) on rearfoot eversion, subtalar pronation, medial longitudinal arch angle (MLAA), hip kinematics and vertical ground reaction force (vGRF).

METHODS

Fifteen healthy female runners underwent gait retraining under three conditions. Participants were instructed to run normally, on the lateral (COP lateral) and medial (COP medial) side of the foot. Foot progression angle (FPA) was controlled using real-time visual feedback. 3D measurements of rearfoot eversion, subtalar pronation, MLAA, FPA, hip kinematics, vGRF and COP were analyzed. A repeated-measures ANOVA followed by pairwise comparisons was used to analyze changes in outcome between three conditions. Data were also analyzed using statistic parameter mapping.

RESULTS

Running on the lateral side of the foot compared to normal running and running on the medial side of the foot reduced peak rearfoot eversion (mean difference (MD) with normal 3.3°, p < 0.001, MD with COP medial 6°, p < 0.001), peak pronation (MD with normal 5°, p < 0.001, MD with COP medial 9.6°, p=<0.001), peak MLAA (MD with normal 2.3°, p < 0.001, MD with COP medial 4.1°, p < 0.001), peak hip internal rotation (MD with normal 1.8°, p < 0.001), and peak hip adduction (MD with normal running 1°, p = 0.011). Running on the medial side of the foot significantly increased peak rearfoot eversion, pronation and MLAA compared to normal running.

SIGNIFICANCE

This study demonstrated that COP translation along the mediolateral foot axis significantly influences rearfoot eversion, MLAA, and subtalar pronation during running. Running with either more lateral or medial COP reduced or increased peak rearfoot eversion, peak subtalar pronation, and peak MLAA, respectively, compared to normal running. These results might use as a basis to help clinicians and researchers prescribe running gait retraining by changing mediolateral COP for runners with atypical rearfoot eversion or MLAA.

Sex Differences in Human Ankle Stiffness During Standing Balance

The purpose of this study is to quantify sex differences in 2-dimensional (2D) ankle stiffness during upright standing balance and investigate the mechanisms for the differences. A dual-axis robotic platform, capable of perturbing the ankle and measuring the corresponding ankle torques in both the sagittal and frontal planes, was used to reliably quantify the 2D ankle stiffness while healthy young human subjects perform a range of standing balance tasks, specifically, ankle muscle co-contraction tasks, weight-bearing tasks, and ankle torque generation tasks. In all task conditions and in both planes of ankle motion, ankle stiffness in males was consistently greater than that in females. Among all 26 experimental conditions, all but 2 conditions in the frontal plane showed statistically significant sex differences. Further investigation on the normalized ankle stiffness, scaled by weight times height, suggests that while sex differences in ankle stiffness in the sagittal plane could be explained by sex differences in anthropometric factors as well as neuromuscular factors, the differences in the frontal plane are mostly explained by anthropometric factors. This study also demonstrates that the sex differences in the sagittal plane were significantly higher as compared to those in the frontal plane. The results in this study will provide a foundation for not only characterizing sex differences in ankle stiffness during locomotion, but also investigating sex differences in lower body stability and risk of ankle injury.

Multipotential stromal cells in the talus and distal tibia in ankle osteoarthritis - Presence, potency and relationships to subchondral bone changes

A large proportion of ankle osteoarthritis (OA) has an early onset and is post‐traumatic. Surgical interventions have low patient satisfaction and relatively poor clinical outcome, whereas joint‐preserving treatments, which rely on endogenous multipotential stromal cells (MSCs), result in suboptimal repair. This study investigates MSC presence and potency in OA‐affected talocrural osteochondral tissue. Bone volume fraction (BV/TV) changes for the loading region trabecular volume and subchondral bone plate (SBP) thickness in OA compared with healthy tissue were investigated using microcomputed tomography. CD271‐positive MSC topography was related to bone and cartilage damage in OA tissue, and in vitro MSC potency was compared with control healthy iliac crest (IC) MSCs. A 1.3‐ to 2.5‐fold SBP thickening was found in both OA talus and tibia, whereas BV/TV changes were depth‐dependent. MSCs were abundant in OA talus and tibia, with similar colony characteristics. Tibial and talar MSCs were tripotential, but talar MSCs had 10‐fold lower adipogenesis and twofold higher chondrogenesis than IC MSCs (P = .01 for both). Cartilage damage in both OA tibia and talus correlated with SBP thickening and CD271+ MSCs was 1.4‐ to twofold more concentrated near the SBP. This work shows multipotential MSCs are present in OA talocrural subchondral bone, with their topography suggesting ongoing involvement in SBP thickening. Potentially, biomechanical stimulation could augment the chondrogenic differentiation of MSCs for joint‐preserving treatments.

Detecting physical abilities through smartphone sensors: an assistive technology application

PURPOSE

It is important to promote assistive technologies to improve quality of life. The proposed SmartAbility Android Application recommends assistive technologies for people with reduced physical abilities, by focussing on actions that can be performed independently.

MATERIALS AND METHODS

The SmartAbility Application uses Android built-in sensors, e.g., accelerometer and gyroscope and application programming interfaces (APIs) to detect physical abilities, e.g., head movements and blowing and recommend suitable assistive technologies. This is supported by a MySQL database that stores assistive technologies and mappings between abilities. The underpinning research is the SmartAbility Framework that culminates the knowledge obtained during previously feasibility trials and usability evaluations.

RESULTS

The Application was evaluated by pupils (n = 18) at special educational needs schools with physical conditions, including cerebral palsy, autism and Noonan syndrome, and assessed through the NASA Task Load Index (TLX) and System Usability Scale (SUS). Analysis using the Adjective Rating Scale highlighted that the Application achieves "Good Usability".

CONCLUSION

The SmartAbility Application demonstrates that built-in sensors of Android devices and their APIs, can detect actions that users perform, e.g., head movements and speaking. The Application contains a database where assistive technologies are mapped to physical abilities, in order to provide suitable recommendations. It will be disseminated to assistive technology charities and manufacturers and be used by healthcare professionals as part of the rehabilitation process. Future developments of SmartAbility include the creation of a second Application designed specifically to recommend assistive technologies for the education sector, based on users' physical and cognitive abilities.IMPLICATIONS FOR REHABILITATIONAssistive technology is any item, equipment or piece of software designed to increase, maintain or improve the functional capabilities of people with disabilities.SmartAbility should be introduced into rehabilitation to promote awareness of assistive technologies that are suitable for the physical abilities of the user.Our research highlighted that physical abilities can be detected using built-in sensors of Android devices, e.g. accelerometer and gyroscope.Involvement of the intended user community during evaluations is essential to ensure that a smartphone application is suitable for people with reduced physical abilities.Assistive technologies can support the rehabilitation of people with reduced physical abilities by providing increased independence and improved quality of life.

Prophylaxis of Pain and Fractures within Feet in the Course of Osteoporosis: The Issue of Diagnosing

Background

Considering the enormous risk of fractures in the course of osteoporosis in the area of the feet, an important aspect of prophylaxis is periodic and, in special cases, ongoing monitoring of defects and deformations as well as pressure distribution. The purpose of this article is to indicate the role of the examination of posture and pressure distribution during standing, postural balance, and gait, in the prevention of fatigue fractures in the course of osteoporosis, based on the literature review and examples of patients.

Methods

The manuscript consists of two parts; it has a review-analytical character. The first part reviews the literature. The data were obtained using the MEDLINE (PubMed), as well as Cochrane and Embase databases. The database review was carried out focusing mainly on English-language publications, while taking into account the topicality of scientific and research works in the area of osteoporosis. The problem of multiaspects in the area of bone density was pointed out. Considering the above, in the second part, the authors analyzed 11 exemplary patients with osteoporosis, referring to the assessment of foot and lower limb defects using traditional posturological methods and including pedobarography to diagnostic procedures that are used in the assessment of pressure distribution, standing and moving, and an attempt to balance.

Results

Analysis of the research and scientific literature proved the lack of unambiguous diagnostic procedures of the locomotor system recommended for the prevention of fatigue fractures in the course of osteoporosis. The main diagnostic recommendations are imaging tests (most often X-ray), which are recommended in the case of specific clinical symptoms. The analysis of exemplary patients with osteoporosis showed numerous disorders in the distribution of pressure in the plantar part of the feet, which are related, among other things, with their individual defects and lower limbs.

Conclusions

Detailed posture diagnostics and gait estimation, along with the analysis of pressure distribution within the feet are a very important aspect of the prevention of structural degradation and fatigue fractures within the feet. An important postulate for further research and scientific work is the elaboration of the procedures that will serve the preventive diagnostics of the locomotor system, aimed at early detection of threats of fatigue fractures.