Ankle Position Research Articles

Comparing Setup Errors Using Portal Imaging in Patients With Gynecologic Cancers by Two Methods of Alignment

AimsAlignment tattoos on a lax abdomen contribute to misalignment of patients undergoing abdomino-pelvic radiotherapy (RT). The present study was undertaken to assess setup reproducibility in gynecologic cancer patients positioned identically but aligned for treatment to machine isocenter by two different ways. Materials and methodsA prospective study in 35 women treated with radical RT for gynecologic malignancy was undertaken. A RT planning contrast-enhanced computed tomography scan in the supine position using an foot and ankle positioning device was done, and three reference points tattooed on the reference plane, anteriorly at the mons pubis and one on each side laterally at a fixed table top-to-vertical height of 10 cm, whereas a fourth point was tattooed at the xiphoid in the anterior midline. Patients were aligned using either a field center, that is, conventional method (Arm I, n = 18) or by a new setup isocenter (Arm II, n = 17) defined by a cranial offset of 4 cm to the reference plane for daily treatment. Anterior and right lateral digitally reconstructed radiograph setup fields were created at the treatment isocenters and compared with orthogonal megavoltage portal images (PI) taken during initial 3 days of RT and subsequently twice weekly. Setup deviations-rotations and translations were analysed in mediolateral (ML), craniocaudal, and anteroposterior direction. No online and offline corrections were performed. Population systematic error and random error were calculated and planning target volume margins required were estimated using van Herk's formula. ResultsArm I had 209 PI while Arm II had 188 PI. Patients in arm II had a lesser systematic error in the ML direction. Patients with large pelvic girth (>95 cm) were susceptible for greater movements during treatment, more so in Arm I, major shifts (>5 mm) with respect to Arm II in the ML direction (37% vs. 22%, P = .001). A larger planning target volume expansion was required in Arm I (1.6 cm) compared with Arm II (0.9 cm). The margin expansion required from clinical target volume in anteroposterior direction was about 0.6 cm and about a cm in the craniocaudal direction in both the arm. ConclusionsAlignment of patient with anterior tattoo at the relatively immobile portion of lower abdomen (mons pubis) Arm II (setup) is superior to a more cranial location over the flabby abdomen during radiation treatment.

Calibration of the shear wave speed-stress relationship in in situ Achilles tendons using cadaveric simulations of gait and isometric contraction

It has been shown that shear wave speed is directly dependent on axial stress in ex vivo tendons. Hence, a wave speed sensor could be used to track tendon loading during movement. However, adjacent soft tissues and varying joint postures may affect the wave speed-load relationship for intact tendons. The purpose of this study was to determine whether the proportional relationship between squared wave speed and stress holds for in situ cadaveric Achilles tendons, to evaluate whether this relationship is affected by joint angle, and to assess potential calibration techniques. Achilles tendon wave speed and loading were simultaneously measured during cadaveric simulations of gait and isometric contractions performed in a robotic gait simulator. Squared wave speed and axial stress were highly correlated during isometric contraction at all ankle postures (R2avg = 0.98) and during simulations of gait (R2avg = 0.92). Ankle plantarflexion angle did not have a consistent effect on the constant of proportionality (p = 0.217), but there was a significant specimen-angle interaction effect (p < 0.001). Wave speed-based predictions of tendon stress were most accurate (average RMS error = 11% of maximum stress) when calibrating to isometric contractions performed in a dorsiflexed posture that resembled the posture at peak Achilles loading during gait. The results presented here show that the linear relationship between tendon stress and squared shear wave speed holds for a case resembling in vivo conditions, and that calibration during an isometric task can yield accurate predictions of tendon loading during a functional task.

Dimensional Changes of the Tarsal Tunnel During Foot and Ankle Positions: Anatomical Study

The tarsal tunnel is a fibrous osseous conduit for the tibial nerve and associated tendons. It is mechanically dynamic, and foot and ankle movements appear to move and change tunnel shape. However, the effect of foot and ankle movements is not clear. The aim of this study was to measure tarsal tunnel dimensions in anatomical position of the foot and ankle and quantify its changes at different positions in cadavers. A cross-sectional study with a total of 16 cryopreserved lower extremities from cadaveric specimens were used. The foot was cut using an anatomical saw at the level of the tarsal tunnel. Measurements of the cross-sectional area (CSA), transverse diameter (TD), longitudinal diameter (LD) were taken in anatomical position and during foot and ankle movements. All the tarsal tunnel measurements were significantly modified by ankle plantar flexion (p < .05). The CSA increased by 68.97 mm2 (p < .001), the TD increased by 1.40 mm (p < .002) and the LD increased by 2.55 mm (p < .007). The TD was also significantly modified by the inversion position of the ankle, showing an increase of 0.84 mm (p < .004). The rest of the ankle positions did not produce significant changes in tarsal tunnel measurements. Foot and ankle plantar flexion position produce and increase in the CSA and the TD of the tarsal tunnel at its distal end in cadavers. This could suggest a reduction in tarsal tunnel pressure during plantar flexion.

Effect of ankle joint position on triceps surae motor unit firing rates

The triceps surae is an interesting model to study the effect of muscle length changes on motor unit properties for two reasons. First, the gastrocnemii components show lower motor unit discharge rates (MUDRs) when shortened by knee joint flexion as compared to an extended knee joint, whereas all other muscles studied display either higher or similar MUDRs in a shortened compared to a lengthened position. Second, the soleus receives strong afferent feedback due to its predominantly type I muscle fiber composition indicating that muscle length changes may have a great effect on its motor unit properties. The limited previous studies have not explored how changes in ankle joint position affect the triceps surae muscles. Thus, the purpose of this study was to compare MUDRs of the bi‐articular medial gastrocnemius (MG) and mono‐articular soleus at two ankle joint positions, 30° dorsiflexion and 20° plantar flexion, during the common task of plantar flexion. Four young, healthy men (~24 years old) were seated upright in a leg dynamometer with both the hip and knee joint angles at 90°. Subjects performed two ~3s isometric plantar flexion maximal voluntary contractions (MVC) at each ankle joint position. Tungsten electrodes were then used to record MUDRs from the MG and soleus during separate steady state 3–10s isometric plantar flexion contractions at 25, 50, 75, and 100% MVC at one ankle joint position. After a series of contractions, the ankle joint angle was changed and the subjects performed another series of plantar flexion contractions at each torque level. Initial ankle joint position and the order of contractions performed were randomized prior to each testing session. Subjects visited the lab multiple times to repeat the intervention in order to sample from many motor units. The mean MVC torque was 53% lower in the shortened (20° plantar flexion; 105Nm) compared to the lengthened (30° dorsiflexion; 223Nm) position. A total of 487 motor units from the MG (n=228) and soleus (n=259) were identified. Mean MG MUDRs at 25, 50, 75 and 100% MVC were lower by 8, 0, 17 and 14%, respectively in the dorsiflexed compared to the plantar flexed position. Similarly, mean soleus MUDRs were lower by 8, 12, 25 and 25% at 25, 50, 75 and 100% MVC, respectively in the dorsiflexed compared to the plantar flexed position. These preliminary findings indicate that shortening the MG and soleus by placing the ankle joint in a plantar flexed position leads to higher MUDRs as compared to a dorsiflexed position. This may serve as a compensatory mechanism for the decreased torque producing capability of the triceps surae in a shortened (plantar flexed) position.Support or Funding InformationFunded by NSERC.

Influence of Menstrual Cycle Phases on Neural Excitability in the Primary Somatosensory Cortex and Ankle Joint Position Sense.

Introduction: Ankle sprain (AS) is one of the most common injuries among women engaged in competitive sports and recreational activities. Many studies have shown that several factors contributing to AS are influenced by the menstrual cycle. Despite the finding that abnormal joint position sense (JPS) is one of the major risk factors of AS, the alteration of the JPS throughout the menstrual cycle and its associated neural mechanisms remain unclear.Objective: This study aimed to examine whether the menstrual cycle phases affect neural excitability in the primary somatosensory cortex (S1) and JPS.Methods: Fourteen right-footed women participated in this study. Somatosensory-evoked potential and paired-pulse inhibition (PPI) were measured to assess S1 excitatory and inhibitory functions. Ankle JPS was measured using an active joint position matching method. Menstrual syndrome was evaluated using the menstrual distress questionnaire. All assessments were conducted in the follicular, ovulatory, and luteal phases.Results: The two main findings of this study were as follows: First, PPI decreased in the ovulatory phase than in the follicular phase. This may have been the reason for estrogen altering the neural inhibition and facilitation balance throughout the menstrual cycle. Second, JPS was not changed during the menstrual cycle.Conclusion: In conclusion, phases of the menstrual cycle affect the neural excitability in S1 as shown by the decreased PPI in the ovulatory phase, and the ankle JPS was unchanged throughout the menstrual cycle.

Performance Characterization and Pressure Prediction of Compression Socks

Objective of the current research is to develop the mathematical model for the prediction of compression pressure by incorporating some of new but missing variables; circumferential aspect of leg (Lc) and socks (Sc), true stress (σT), true/logarithm strain (eT), true modulus of elasticity (ET), deformed width (Wf) at b ankle position. Socks samples were purchased, hand washed, donned, marked, sliced to loops and then cut to rectangular strips to obtain force-elongation curve at different extensions context to practical elongation. Additionally, all samples were evaluated to analyze the influnce of multiple-machine washes as well as for identification of most influential fabric parameter on compresson pressure, statistically. Standard sized wooden leg (S9=24 cm) attached with pneumatic based sensors (Salzmann MST MK IV) to medial side was used. Force-extension diagram was obtained using Testometric tensile tester. Mathematical models were developed on the basis of principle of Laplace’s law. Developed two models were analyzed and comapred with two existing recently developed models statitistically using MINTAB 17 software.

New approach for the prediction of compression pressure using the cut strip method

The main objective of the current research is the development of a new mathematical model for the prediction of compression pressure based on the incorporation of some new parameters. These new parameters include deformed width (wf), true stress ([Formula: see text]), true/logarithm strain ([Formula: see text]), true modulus of elasticity ([Formula: see text]), along with measurement of engineering stress ([Formula: see text]), engineering strain ([Formula: see text]) and engineering modulus of elasticity ([Formula: see text]) at ankle position. Various brands of compression socks comprising similar fibrous combinations, as well as knit type, were purchased. Initially they were hand washed, put on the leg for marking, marked in a square, sliced, and cut into rectangular strips. The rectangular cut strips were evaluated for force–elongation characterization at different strain values considering the requisite practical elongation values (circumferential difference between leg and sock at ankle portion). For pressure measurement, a Salzmann MST MK IV pressure measuring device using a standard-sized wooden leg (circumference = 240 mm) was used. For tensile evaluation, a Testometric tensile tester was used. In this research we developed the two mathematical models based on true Young’s modulus and engineering Young’s modulus were compared with Hooke’s law and Laplace’s law. The developed models were also compared with previously existing models statistically.

Sonographic visibility of the main posterior ankle ligaments and para-ligamentous structures in 15 healthy subjects.

The present article describes the ultrasound (US) appearance of ligaments and paraligamentous structures which are not included in standard US imaging of the ankle: the posterior inferior tibiofibular ligament (PITFL), the transverse tibiofibular ligament (TTFL), the posterior talofibular ligament (PTFL), the posterior intermalleolar ligament (PIL), the synovial recess (SR) of the posterior joint and the os trigonum (OT). Two skilled operators examined 15 ankles in 15 healthy volunteers. Correlation between thickness of the main ligaments and body mass index (BMI) was also analyzed. Compound and tissue harmonic imaging (THI) were carried out using 12-, 6-15- and 9-MHz linear probes. Exploration of the posterior ankle ligament complex is accurately described including correct ankle position, echogenicity, shape, direction and thickness. Both operators identified and measured the main ligaments (PITFL, TTFL and PTFL) in all volunteers (Intraclass Correlation Coefficient ranged from 0.8 to 1); both operators also detected SR and OT in 2/15 ankles and posterior intermalleolar ligament (PIL) in 5/15 ankles. Pearson's test showed a significant correlation (< 0.05) between TTFL thickness and BMI. Also, a dynamic study was carried out showing tension of the PTFL during dorsiflexion in 7/15 subjects. Our results highlight the potential role of accurate US imaging in detecting posterior ankle ligament involvement in acute and chronic traumas. To our knowledge, there are no previous articles in the literature dealing with this topic providing an accurate description of the US procedure, and in particular, no study has been carried out to identify OT.

Patterns of muscle activation and modulation of ankle intrinsic stiffness in different postural operating conditions.

Intrinsic stiffness describes the dynamic relationship between imposed angular perturbations to a joint and the resulting torque response, due to intrinsic mechanical properties of muscles and joint, and inertia of the limbs. Recently, we showed that ankle intrinsic stiffness changes substantially with sway in normal standing. In the present study, we documented how ankle intrinsic stiffness changes with postural operating conditions. Subjects stood on an apparatus while subjected to ankle position perturbations in five conditions: normal standing, toe-up and toe-down standing, and backward and forward lean. In each condition, ankle intrinsic stiffness was estimated while its modulation with sway was accounted for. The results demonstrated that ankle intrinsic stiffness varies widely, from 0.08 to 0.75 of critical stiffness, across postural operating conditions; however, it is always smaller than the critical stiffness. Therefore, other contributions are necessary to ensure stable standing. The mean intrinsic stiffness was highest in forward lean and lowest in backward lean. Moreover, within each operating condition, the intrinsic stiffness changed with center-of-pressure position in one of three ways, each associated with a distinct muscle activation pattern; these include 1) monotonically increasing stiffness-center of pressure relation, associated with a progressive increase in triceps surae activation, 2) decreasing-increasing stiffness-center of pressure relation, associated with initial activation of tibialis anterior and later activation of triceps surae, and 3) monotonically decreasing stiffness-center of pressure relation, associated with decreasing activation of tibialis anterior. Thus intrinsic stiffness varies greatly within and across postural operating conditions, and a correct understanding of postural control requires accounting for such variations.NEW & NOTEWORTHY Ankle intrinsic stiffness changes with sway in normal standing. We quantified such changes in different postural operating conditions and demonstrated that the intrinsic stiffness changes in a manner associated with different activation patterns of ankle plantarflexors and dorsiflexors, emerging in different operating conditions. Large modulations of the intrinsic stiffness within and across postural operating conditions show that the stiffness importance and contribution change and must be accounted for in the study of postural control.

A Bayesian extension of phylogenetic generalized least squares: Incorporating uncertainty in the comparative study of trait relationships and evolutionary rates.

Phylogenetic comparative methods use tree topology, branch lengths, and models of phenotypic change to take into account nonindependence in statistical analysis. However, these methods normally assume that trees and models are known without error. Approaches relying on evolutionary regimes also assume specific distributions of character states across a tree, which often result from ancestral state reconstructions that are subject to uncertainty. Several methods have been proposed to deal with some of these sources of uncertainty, but approaches accounting for all of them are less common. Here, we show how Bayesian statistics facilitates this task while relaxing the homogeneous rate assumption of the well-known phylogenetic generalized least squares (PGLS) framework. This Bayesian formulation allows uncertainty about phylogeny, evolutionary regimes, or other statistical parameters to be taken into account for studies as simple as testing for coevolution in two traits or as complex as testing whether bursts of phenotypic change are associated with evolutionary shifts in intertrait correlations. A mixture of validation approaches indicates that the approach has good inferential properties and predictive performance. We provide suggestions for implementation and show its usefulness by exploring the coevolution of ankle posture and forefoot proportions in Carnivora.

Comparison of Muscle Activity Based on Ankle Position During Hip Abduction

Comparison of Muscle Activity Based on Ankle Position During Hip Abduction

Joint position sense of lower extremities is impaired and correlated with balance function in children with developmental coordination disorder.

To determine the joint position sense of the lower extremities and its relationship with motor function in children with developmental coordination disorder (DCD) and typically developing (TD) children. A total of 56 participants were recruited; 28 children with DCD (age 10.86±1.07 years; 13 females, 15 males) and 28 TD children (age 10.96±1.18 years; 12 females, 16 males). Knee and ankle joint position sense were assessed using a Biodex isokinetic dynamometer. Joint position acuity was measured by position error (PE) and position error variability (PEV). Motor function was examined using the 2nd edition of Movement Assessment Battery for children (MABC-2) and quantified via sub-scores from 3 MABC-2 domains. Both PE and PEV at knee and ankle joints were significantly greater in children with DCD compared with TD children. In addition, both PE and PEV were significantly greater at the ankle joints than the knee joints in children with DCD. For children with DCD only, joint position acuity in the lower extremities significantly and negatively correlated with MABC-2 balance sub-score. This study verifies that lower limb proprioception is impaired in children with DCD. Also, children with DCD displayed greater proprioceptive deficits at the ankle compared with the knee joint. Children with DCD who had poorer joint position acuity, i.e. greater PE and PEV, in the lower extremities tended to perform less well in balance function.

Morphological changes in the long axis of the lower leg muscles during isometric contraction in the sitting position.

[Purpose] To compare the changes in the muscle cross-sectional area (MCSA) along the long axis of the lower leg muscles at rest and during ankle plantar flexors isometric contraction and to obtain basic information regarding the movement of lower leg muscles during ankle plantar flexors contraction. [Participants and Methods] Sixteen healthy young female participants (20.9 ± 1.2 years) were asked to sit with their ankles in a neutral ankle position. Images were obtained at rest and during isometric contraction of the ankle plantar flexors using gravity magnetic resonance imaging. The MCSAs of the triceps surae and tibialis anterior were measured. [Results] The middle region of the soleus muscle had a lower MCSA on contraction than at rest. In addition, the medial head of the gastrocnemius had a lower MCSA on contraction than at rest in the distal quarter. Moreover, the tibialis anterior had a lower MCSA at rest than on contraction in the middle region. [Conclusion] The area to be used as an indicator and the movement to be induced differ depending on the muscle during isometric contraction of the triceps surae.

Lower extremity proprioceptive sensation in patients with early stage knee osteoarthritis: A comparative study

BackgroundKnee OA causes pain and proprioceptive impairment. The body acts as a closed kinetic chain, and deformation on the knee cannot only affect the knee joint but also can affect the other joints. ObjectiveTo assess the proprioception of lower extremity in early stage knee osteoarthritis compared with without knee osteoarthritis individuals. MethodsThe study sample consisted of 26 adults with early stage knee osteoarthritis and 26 subjects without knee osteoarthritis individuals. Western Ontario and McMaster Universities Osteoarthritis Index was used for clinical disease severity. Visual Analogue Scale was used for pain severity. Proprioception (position and motion sense) was measured by isokinetic dynamometer. ResultsWestern Ontario and McMaster Universities Osteoarthritis Index total score was 10.9 ± 5. Visual Analogue Scale scores during activity were found to be significantly higher than the scores at rest and night for both sides. Hip flexion and internal rotation joint position sense were significantly different between two groups (all p's < 0.05). Hip abduction, knee flexion, ankle and subtalar position sense, as well as hip and knee motion sense were similar between groups (all p's > 0.05). Ankle dorsiflexion and eversion motion sense were significantly different between two groups (all p's < 0.05). ConclusionsThis study demonstrated that the hip flexion and internal rotation position sense and ankle/subtalar joints motion sense may be affected on early stage of knee osteoarthritis. Investigation of the mechanism of proprioception for joints and also focusing on the longitudinal relationship between proprioception, knee OA disease and symptoms is recommended for future studies.

Biomechanical Analysis of a Novel Syndesmotic Plate Compared With Traditional Screw and Suture Button Fixation

Many lateral malleolus fractures have been found to have syndesmosis injuries after anatomic reduction. The main methods for the treatment of syndesmosis injuries are screw fixation and suture-button flexible fixations. In pursuit of innovation, we have designed a novel syndesmotic plate (NSP) for simultaneous fixation of lateral malleolus fractures and distal tibiofibular syndesmosis injuries. The purpose of this study is to compare the biomechanical characteristics of the NSP to syndesmotic screw and suture-button fixations. Twelve adult cadaveric specimens were used in this experiment. Axial loading as well as rotation torque were applied in 3 different ankle positions: neutral, dorsiflexion, and plantarflexion. After the initial specimens were tested, they were made into a pronation-abduction III fracture model as described by Lauge-Hansen. Subsequently, the specimens were fixed sequentially using a distal fibular anatomic locking plate (DFALP) combined with syndesmotic screws, DFALP combined with suture button, and NSP. Then the above tests were repeated. The syndesmotic displacement and the strain of the tibia and fibula were recorded during the experiment. In most cases, the displacements and strains of the NSP group and the screw group were smaller than the suture button groups and the native (SBGAN) (p < .05), and the displacements and strains of the NSP group were also slightly smaller than the screw group in most cases, and there was no significant difference between the 2 groups. The NSP we developed has a fixed strength no less than the traditional syndesmotic screw fixation. This provides us a new idea for the treatment of distal tibiofibular syndesmosis injuries.

Effect of disturbances and sensorimotor deficits on the postural robustness of an ankle–hip model of balance on a balance board

This paper investigates the effect of postural disturbances and sensorimotor deficits on the robustness of the upright posture (UP) for a human body model balancing on a balance board (BB). The robustness is investigated by computing the gradient field along the basin of attraction (BoA) of an asymptotically stable equilibrium point. The human model is modeled as a double-inverted pendulum (hip and ankle joints). The human-BB system is assumed actuated by torques at the hip, BB hinge, and ankle joints. Postural disturbances induce an initial joint angle velocity either at the ankle or at the hip joint. Moreover, either proprioceptive or visual and vestibular deficits are considered in the human-BB model. The nonlinear dynamic equation of motion of the human-BB system is numerically solved to obtain the BB, ankle, and hip joint angle position and velocity profiles. The BoA of the human-BB UP equilibrium is built as the set of initial conditions whose resulting time-series profiles converge to the equilibrium. It was shown that UP is more robust to disturbances that induce hip joint initial angle velocity. That is probably due to the fact that disturbances that induce ankle joint initial velocity affect the whole body, while disturbances that induce hip joint angle initial velocity only affect the trunk. Whenever visual and vestibular deficits are considered, the UP is more robust if proprioceptive gain and BB stiffness are small. Contrarily, whenever proprioceptive deficits are considered, the UP is more robust if visual and vestibular gain and BB stiffness are large. The method proposed here (the BoA and the gradients) can be used to systemically provide understanding about the robustness of the human-BB UP to external disturbances, which may help to identify people with a higher risk of fall.

Does Acute Fatigue Negatively Affect Intrinsic Risk Factors of the Lower Extremity Injury Risk Profile? A Systematic and Critical Review.

Acute fatigue is hypothesized to alter lower extremity injury risk profiles by affecting intrinsic risk factors (i.e. single leg postural control, hamstring strength). However, no systematic overview exists that merges the insights into prospective lower extremity injury risk profiling with the effect of acute fatigue on functional test performance. The objective of this review is to identify the influence of acute fatigue on prospectively determined modifiable intrinsic risk factors for lower extremity injuries. Systematic review. PubMed (MEDLINE), Web of Science, PEDro, and Cochrane Library were searched until 29 May 2019. Studies were eligible when the study outcomes encompassed intrinsic modifiable risk factors for lower extremity injury, an acute fatigue intervention, and included healthy athletes or physically active people. Intrinsic modifiable risk factors were identified through recent systematic reviews and meta-analyses, and the referenced original research papers were used to determine outcome measures associated with increased injury risk. Forty-three studies reported acute fatigue effects on modifiable risk factors, with eight studies matching all criteria for data-extraction. Acute fatigue can decrease single leg postural control, decrease ankle joint position sense, decrease isokinetic strength of hamstring and quadriceps muscles and can affect isokinetic hamstring:quadriceps ratios. Acute fatigue affects prospective intrinsic modifiable risk factors for lower extremity injury, indicating an altered injury risk profile for lateral ankle sprain, patellofemoral pain syndrome and hamstring injuries. Future research should allow for individual fatiguability as a relevant outcome, and merge insights from athlete-centred injury risk profiling and fatigue.

Human Gait Recognition Using Hip, Knee and Ankle Joint Ratios

The estimation of joint angle ratios for healthy and afflicted subjects in characterizing the human gait has great significance in the development of limb prosthetics. The two dimensional analysis of human gait was performed and the ratio of hip to knee, knee to ankle, hip to ankle as well as the time taken for achieving a gait were determined. The percentage of affliction was computed based on the joint angle ratios and comparison was made with healthy gait. The joint ratios were fed as input to the driving system which comprises of six DC motors for the positioning of knee, hip and ankle during gait. Then different control strategies like P, PI and PID were tested. The t-test and ANOVA analysis were conducted between healthy, afflicted and PID controller to determine the significant difference between their joint angle ratios. The estimation of joint angle ratio improved the accuracy of the control system drive (desired position of knee, hip and ankle motors). The presence of oscillations in the output response was reduced for P and PI controllers. The implementation of PID controller eliminated the presence of peak overshoot and more settling time. Thus the joint angle ratio provides the best possible assistance to the disabled persons by appropriately compensating the affliction.

Dimensional Changes of the Tibial Nerve and Tarsal Tunnel in Different Ankle Joint Positions in Asymptomatic Subjects

The tarsal tunnel is a clinically important fibrous osseous conduit for the tibial nerve and associated tendons. It is mechanically dynamic, and normal ankle movements appear to change the tunnel shape, potentially having an impact on the tibial nerve. The objective of this study was to measure changes in the tibial nerve and tarsal tunnel dimensions in plantarflexion and dorsiflexion of the ankle joint in healthy subjects. A cross-sectional study with 13 volunteer subjects and a total of 18 records was designed. The cross-sectional area, anterior-posterior distance, transverse distance, and flattening ratio of the tibial nerve were measured by using ultrasound in plantarflexion and dorsiflexion of the ankle joint. The anterior-posterior distance of the tarsal tunnel was also measured. The tunnel anterior-posterior distance significantly increased during plantarflexion (p < .001) and decreased during dorsiflexion (p = .027) of the ankle. From plantarflexion to dorsiflexion of the ankle, the tibial nerve cross-sectional area significantly decreased (p = .035). The anterior-posterior distance also decreased significantly (p < .001), whereas the transverse distance increased (p < .001), thus decreasing the flattening ratio of the tibial nerve (p < .001). Ankle joint position determined significant changes in the shape and dimensions of the tibial nerve at the tarsal tunnel.

Effects of ankle position during static stretching for the hamstrings on the decrease in passive stiffness

Static stretching is frequently performed to improve flexibility of the hamstrings, although the ankle position during hamstring stretching has not been fully investigated. We investigated the effects of ankle position during hamstring stretching on the decrease in passive stiffness. Fourteen healthy men performed static stretching for the hamstrings with the ankle dorsiflexed and plantar-flexed in a randomized order on different days. The hip was passively flexed to the maximum angle which could be tolerated without stretch pain with the knee fully extended; this was maintained for 5 min, with 1-min stretching performed in 5 sessions. Final angles and passive stiffness were measured before and after stretching. The final angle was defined as that formed by the tibia and horizontal plane when the knee was passively extended from hip and knee angles at 90° flexion to the maximum extension angle which could be tolerated without stretch pain. Passive stiffness was determined by the slope of torque–angle curve during the measurement of the final angle. The final angle significantly increased after stretching with the ankle dorsiflexed and plantar-flexed, whereas passive stiffness significantly decreased only after stretching with the ankle planter-flexed. The results suggest that passive stiffness decreases after stretching with the ankle planter-flexed but not after stretching with the ankle dorsiflexed, although the range of joint motion increases regardless of the ankle position during 5-min stretching for the hamstrings. These results indicate that static stretching should be performed with the ankle plantar-flexed when aiming to decrease passive stiffness of the hamstrings.