Walking Stance Research Articles

Mechanical Orthosis with Rotation Induction to Lower Leg for Patients with Knee Osteoarthritis.

Knee osteoarthritis (Knee-OA) is a disease caused by age-related muscle weakness, obesity, or sports injury, and it has been estimated to occur in approximately half of all people by the age of 85. One of the characteristics of knee-OA is rotation dyskinesia of the knee joint due to the degeneration of the system around the knee. This rotation movement, a key element of walking, is crucial for impact absorption, balanced walking, and stabilization of the knee joint. In the present study, we focused on the rotation of the lower leg relative to the movement of the ankle joint during the walking stance phase, and we developed a mechanical orthosis that induces rotation of the lower leg in conjunction with the movement of the ankle joint mechanically. The mechanical induction of rotation movement uses the movement difference due to the angle change of the inside and outside bars in conjunction with the ankle angle. We verified the effectiveness of the developed orthosis by measuring the amount of rotation and by administering the Womac test in 5 subjects with knee osteoarthritis. The results confirmed the effectiveness of our orthosis.

Finite element simulation on posterior tibial tendinopathy: Load transfer alteration and implications to the onset of pes planus

BackgroundPosterior tibial tendinopathy is a challenging foot condition resulting in pes planus, which is difficult to diagnose in the early stage. Prior to the deformity, abnormal internal load transfer and soft tissue attenuation are anticipated. The objective of this study was to investigate the internal load transfer and strain of the ligaments with posterior tibial tendinopathy, and the implications to pes planus and other deformities. MethodsA three-dimensional finite element model of the foot and ankle was reconstructed from magnetic resonance images of a 28-year-old normal female. Thirty bones, plantar fascia, ligaments and tendons were reconstructed. With the gait analysis data of the model subject, walking stance was simulated. The onset of posterior tibial tendinopathy was resembled by unloading the tibialis posterior and compared to the normal condition. FindingsThe load transfer of the joints at the proximal medial column was weaken by posterior tibial tendinopathy, which was compromised by the increase along the lateral column and the intercuneiforms during late stance. Besides, the plantar tarsometatarsal and cuboideonavicular ligaments were consistently over-stretched during stance. Particularly, the maximum tensile strain of the plantar tarsometatarsal ligament was about 3-fold higher than normal at initial push-off. InterpretationPosterior tibial tendinopathy altered load transfer of the medial column and unbalanced the load between the proximal and distal side of the medial longitudinal arch. Posterior tibial tendinopathy also stretched the midfoot plantar ligaments that jeopardized midfoot stability, and attenuated the transverse arch. All these factors potentially contributed to the progress of pes planus and other foot deformities.

말의 4족 보법에서 속도변화에 따른 전족 움직임의 운동능력 분석

Objective : The purposes of this study was to analyze the locomotive movement of forelimbs according to changes in velocities in the quadruped cadence of horses. Methods : Horses selected as subjects consisted of Jeju pony horses (heights of withers: 1.23±0.51). Two camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) were used to capture the movement of the horses’ forelimbs at a rate of 60 frames/sec. Additionally, raw data was collected from Kwon3D XP motion analysis package ver 4.0 program (Visol, Korea) with DARTFISH (DFKREA., Korea) video software solution. The variables analyzed consisted of 1 step lengths, 1 stride lengths, stance time, swing time, 1 stride time, velocity while walking, and trot of the horses. A two-way ANOVA and paired t-test of the variables by velocity and phase were treated at .05 level of significant difference, statistically. Results : The time elapsed of walk(stance: 0.63 sec[63.86%], swing: 0.35 sec[36.14%], 1 stride time: 0.99 sec respectively) showed significant difference with more delay than that of trot(stance: 0.29 sec[45.73%], swing: 0.34 sec[54.27% ], 1 stride time: 0.63 sec respectively), and also showed significant difference at trot in interaction (stance time>tort swing>walk swing>walk stance). The 1 step lengths and stride lengths in trot showed significant difference with longer than that of walk. Velocity of Trot showed significant difference statistically with higher than that of walk Conclusion : The horses’ velocity during 1 step lengths and 1 stride lengths showed a proportional relationship, but the correlation between the horses’ velocity and stance time showed a negative relationship during the quadruped cadence.

Functional restoration and risk of non-union of the first metatarsocuneiform arthrodesis for hallux valgus: A finite element approach

First metatarsocuneiform arthrodesis is one of the surgical interventions to correct hallux valgus, especially those with hypermobile first ray. There is lacking of biomechanical investigations to assess this operation. The objective of this study was to explore the functional restoration and the risk of non-union after the surgery via finite element analysis.A three-dimensional foot model was constructed from a female aged 28 via magnetic resonance imaging. Thirty bones and encapsulated bulk tissue were modeled. Walking stance was simulated by the gait analysis data of the same participant. Parts of the first metatarsal and cuneiform were resected and the bone graft was assigned with the same stiffness as adjacent bones to resemble the surgery of first metatarsocuneiform arthrodesis.The third principal stress of the first metatarsal at midstance (25% stance) and push off (60% stance) was increased by 76% and 139% respectively after the operation, while that of the second metatarsal was decreased by 14% and 66%. The operation reduced the medial deviation of the first metatarsal head by about 3.5mm during initial push off (60% stance). Besides, the bone graft could experience tensile stress inferiorly (26.51MPa).In conclusion, the increase of stress on the first metatarsal and the reduced medial excursion of the first metatarsal head after the simulated operation reflected that metatarsocuneiform arthrodesis could restore the load-bearing function of the first ray. However, inter-fragmentary compression could not be guaranteed. The appropriate course of hardware and non-weight-bearing protocol should be noted and further investigated.

Task-related modulation of crossed spinal inhibition between human lower limbs

Crossed reflex action mediated by muscle spindle afferent inputs has recently been revealed in humans. This raised the question of whether a complex spinal network involving commissural interneurons receiving inputs from proprioceptors and suprasegmental structures, as described in cats, persists in humans and contributes to the interlimb coordination during movement. First, we investigated the neurophysiological mechanisms underlying crossed reflex action between ankle plantar flexors and its corticospinal control from primary motor cortex. Second, we studied its modulation during motor tasks. We observed crossed inhibition in contralateral soleus motoneurons occurring with about 3 ms central latency, which is consistent with spinal transmission through oligosynaptic pathway. The early phase of inhibition was evoked with lower stimulus intensity than the late phase, suggesting mediation by group I and group II afferents, respectively. The postsynaptic origin of crossed inhibition is confirmed by the finding that both H-reflex and motor-evoked potential were reduced upon conditioning stimulation. Transcranial magnetic stimulation over ipsilateral and contralateral primary motor cortex reduced crossed inhibition, especially its late group II part. Last, late group II crossed inhibition was particularly depressed during motor tasks, especially when soleus was activated during the walking stance phase. Our results suggest that both group I and group II commissural interneurons participate in crossed reflex actions between ankle plantar flexors. Neural transmission at this level is depressed by descending inputs activated by transcranial magnetic stimulation over the primary motor cortex or during movement. The specific modulation of group II crossed inhibition suggests control from monoaminergic midbrain structures and its role for interlimb coordination during locomotion.

Redistribution of knee stress using laterally wedged insole intervention: Finite element analysis of knee–ankle–foot complex

BackgroundLaterally wedged insoles are widely applied in the conservative treatment for medial knee osteoarthritis. Experimental studies have been conducted to understand the effectiveness of such an orthotic intervention. However, the information was limited to the joint external loading such as knee adduction moment. The internal stress distribution is difficult to be obtained from in vivo experiment alone. Thus, a three-dimensional finite element model of the human knee–ankle–foot complex, together with orthosis, was developed in this study and used to investigate the redistribution of knee stress using laterally wedged insole intervention. MethodsLaterally wedged insoles with wedge angles of 0, 5, and 10° were fabricated for intervention. The subject-specific geometry of the lower extremity with details was characterized in the reconstruction of MR images. Motion analysis data and muscle forces were input to drive the model. The established finite element model was employed to investigate the loading responses of tibiofemoral articulation in three wedge angle conditions during simulated walking stance phase. FindingsWith either of the 5° or 10° laterally wedged insole, significant decreases in von Mises stress and contact force at the medial femur cartilage region and the medial meniscus were predicted comparing with the 0° insole. InterpretationThe diminished stress and contact force at the medial compartment of the knee joint demonstrate the immediate effect of the laterally wedged insoles. The intervention may contribute to medial knee osteoarthritis rehabilitation.

Amputee socks

The term 'sock ply' may be a source of confusion in prosthetics practice because there may not be a consistent relationship between sock ply and sock thickness. The purpose of this study was to characterize how sock ply related to sock thickness for different sock materials commonly used in limb prosthetics. We also evaluated how sock thickness changed under loading conditions experienced while wearing a lower limb prosthesis compared with unstressed conditions. Experimental. Mechanical assessment. Seven sock materials of varying ply and sheaths were tested using a custom instrument. Sock thickness under eight different compressive stress conditions and two different biaxial in-plane tensile strain conditions were measured. For socks woven from a single material, thickness under walking stance phase conditions averaged 0.7, 1.2 and 1.5 mm for 1, 3 and 5-ply, respectively. For socks woven from several materials, the corresponding results were 0.4, 0.7 and 0.8 mm, respectively. Sock ply did not sum, e.g. a 3-ply sock was not three times the thickness of a 1-ply sock. Sock thickness and compressive stiffness are strongly dependent upon sock material, interface pressure, and in-plane biaxial strain.

Task-dependent activity of motor unit populations in feline ankle extensor muscles.

Understanding the functional significance of the morphological diversity of mammalian skeletal muscles is limited by technical difficulties of estimating the contribution of motor units with different properties to unconstrained motor behaviours. Recently developed wavelet and principal components analysis of intramuscular myoelectric signals has linked signals with lower and higher frequency contents to the use of slower and faster motor unit populations. In this study we estimated the relative contributions of lower and higher frequency signals of cat ankle extensors (soleus, medial and lateral gastrocnemii, plantaris) during level, downslope and upslope walking and the paw-shake response. This was done using the first two myoelectric signal principal components (PCI, PCII), explaining over 90% of the signal, and an angle θ, a function of PCI/PCII, indicating the relative contribution of slower and faster motor unit populations. Mean myoelectric frequencies in all walking conditions were lowest for slow soleus (234 Hz) and highest for fast gastrocnemii (307 and 330 Hz) muscles. Motor unit populations within and across the studied muscles that demonstrated lower myoelectric frequency (suggesting slower populations) were recruited during tasks and movement phases with lower mechanical demands on the ankle extensors--during downslope and level walking and in early walking stance and paw-shake phases. With increasing mechanical demands (upslope walking, mid-phase of paw-shake cycles), motor unit populations generating higher frequency signals (suggesting faster populations) contributed progressively more. We conclude that the myoelectric frequency contents within and between feline ankle extensors vary across studied motor behaviours, with patterns that are generally consistent with muscle fibre-type composition.

The Effects of Railroad Ballast Surface and Slope on Rearfoot Motion in Walking

The purpose of this study was to investigate the effects of transversely sloped ballasted walking surface on gait and rearfoot motion (RFM) parameters. Motion analysis was performed with 20 healthy participants (15 male and 5 female) walking in six surface-slope conditions: two surfaces (solid and ballasted) by three slopes (0, 5, and 10 degrees). The gait parameters (walking velocity, step length, step rate, step width, stance time, and toe-out angle) showed significant surface effect (p = .004) and surface-slope interaction (p = .017). The RFM motion parameters (peak everted/inverted position, eversion/inversion velocity, and acceleration) revealed significant surface (p = .004) and slope (p = .024) effects. The ballasted conditions showed more cautious gait patterns with lower walk velocity, step length, and step rate and longer stance time. In the RFM parameters, the slope effect was more notable in the solid conditions due to the gait adaptations in the ballasted conditions. Ballast conditions showed reduced inversion and increased eversion and RFM range. The RFM data were comparable to other typical walking conditions but smaller than those from running.

Activity Patterns and Timing of Muscle Activity in the Forward Walking and Backward Walking Stick InsectCarausius morosus

Understanding how animals control locomotion in different behaviors requires understanding both the kinematics of leg movements and the neural activity underlying these movements. Stick insect leg kinematics differ in forward and backward walking. Describing leg muscle activity in these behaviors is a first step toward understanding the neuronal basis for these differences. We report here the phasing of EMG activities and latencies of first spikes relative to precise electrical measurements of middle leg tarsus touchdown and liftoff of three pairs (protractor/retractor coxae, levator/depressor trochanteris, extensor/flexor tibiae) of stick insect middle leg antagonistic muscles that play central roles in generating leg movements during forward and backward straight walking. Forward walking stance phase muscle (depressor, flexor, and retractor) activities were tightly coupled to touchdown, beginning on average 93 ms prior to and 9 and 35 ms after touchdown, respectively. Forward walking swing phase muscle (levator, extensor, and protractor) activities were less tightly coupled to liftoff, beginning on average 100, 67, and 37 ms before liftoff, respectively. In backward walking the protractor/retractor muscles reversed their phasing compared with forward walking, with the retractor being active during swing and the protractor during stance. Comparison of intact animal and reduced two- and one-middle-leg preparations during forward straight walking showed only small alterations in overall EMG activity but changes in first spike latencies in most muscles. Changing body height, most likely due to changes in leg joint loading, altered the intensity, but not the timing, of depressor muscle activity.

Temporal couplings between rearfoot–shank complex and hip joint during walking

Background Rearfoot pronation–supination and hip internal–external rotation are commonly assumed to be temporally coupled. Many mechanisms of musculoskeletal injury are proposed based on this assumption. Previous studies suggested that this theoretical coupling does not exist. However, recent experimental studies observed relationships consistent with foot–hip mechanical interdependence. Methods Three-dimensional kinematics of the lower extremity of 18 healthy subjects, wearing flat trekking sandals, was measured during the stance phase of normal walking. Rearfoot–shank complex motion in the transverse plane (shank internal–external rotation) and frontal plane (rearfoot eversion–inversion) and hip motion in the transverse plane were analyzed. Cross-correlation coefficients were calculated to investigate temporal similarities between curves of rearfoot–shank and hip motions. Pearson correlations were used to investigate relationships between the timings of the peaks of these motions. Findings Cross-correlations revealed a strong mean temporal coupling (mean r = 0.77, range 0.56 to 0.92) between shank internal–external rotation and hip internal–external rotation and a moderate mean temporal coupling (mean r = 0.56, range 0.37 to 0.78) between rearfoot eversion–inversion and hip internal–external rotation. Pearson correlations revealed significant ( P ≤ 0.031) moderate relationships of timing of peak shank internal rotation ( r = 0.45) and timing of peak rearfoot eversion ( r = 0.62) with timing of peak hip internal rotation. Interpretation The findings suggest a temporal coupling of rearfoot pronation with hip internal rotation and rearfoot supination with hip external rotation during walking stance. The between-subjects variability of curves' temporal similarities and the moderate relationships between timings of motion peaks indicate that coupling strength should be clinically addressed on an individual basis.

Seeking functions for spinal recurrent inhibition

In this issue of The Journal of Physiology, Lamy et al. (2008) describe a rhythmic modulation of recurrent inhibition during walking in man. This provides some insight into the function of recurrent inhibition, first described by Renshaw (1941) as an inhibition of cat motoneurones produced by antidromic stimulation of the axons of neighbouring motoneurones (homonymous action). Subsequent work, also in cats, showed that motor axon collaterals activate interneurones (the eponymous Renshaw cells) that in turn inhibit motoneurones. Actions extend to more distant muscle groups (heteronymous) and parallel the pattern of heteronymous monosynaptic excitation from muscle spindle Ia afferents. Renshaw cells receive peripheral sensory and descending inputs and have output connections to other spinal interneurones and to other Renshaw cells. So recurrent inhibition is more than just negative feedback from and to motoneurones and may have several functions depending upon motor context. Lamy et al. have focused on heteronymous actions (which are more widespread in man than in cats or monkeys) in the context of our unique bipedal form of walking. The knee extensor quadriceps is a source of recurrent inhibition to the ankle extensor and the flexor muscles soleus and tibialis anterior. But given that these ankle muscles are antagonists, how is differential activation achieved? The authors found that around heel strike and early in stance, when quadriceps is active and soleus activity is increasing, recurrent inhibition of soleus is weak. Conversely, later in stance, when quadriceps is active and soleus activity is declining, recurrent inhibition of soleus is strong. Recurrent inhibition of tibialis anterior motoneurones was neither task nor phase dependent. The reduction in soleus recurrent inhibition would assist the transition from swing to stance and enhanced inhibition later in stance would favour the transition from stance to swing by reducing reciprocal inhibition of tibialis anterior. The origin of these changes in recurrent inhibition remains uncertain but activity of peripheral sensory or descending motor pathways could be involved. Two interesting possibilities are the corticospinal pathway, known to depress homonymous recurrent inhibition of soleus in sitting subjects (Mazzocchio et al. 1994) and the vestibulospinal pathway that depresses recurrent inhibition of soleus in standing stance (Iles & Pisini, 1992). It might be possible to extend such studies to heteronymous actions in walking stance. More meticulous experiments built upon the framework of human research protocols pioneered by the Paris group will likely increase our understanding of recurrent inhibition even further.

Walk-related mimic word activates the extrastriate visual cortex in the human brain: An fMRI study

I present an fMRI study demonstrating that a mimic word highly suggestive of human walking, heard by the ear with eyes closed, significantly activates the visual cortex located in extrastriate occipital region (BA19, 18) and superior temporal sulcus (STS) while hearing non-sense words that do not imply walk under the same task does not activate these areas in humans. I concluded that BA19 and 18 would be a critical region for generating visual images of walking and related intentional stance, respectively, evoked by an onomatopoeia word that implied walking.

Factors associated with falling in patients with Parkinson's disease and atypical parkinsonism: An assessment using the Tinetti Gait and Balance Scale

Aim: To identify factors associated with falling, we assessed the Tinetti Gait and Balance Scale (TGBS) for patients with Parkinson’s disease (PD) and atypical parkinsonism (AP), and assessed the Unified Parkinson’s Disease Rating Scale (UPDRS) for patients with PD. Methods: A cross sectional study was conducted in a university hospital, with the subject constituting 30 PD patients and 22 AP patients. Each item included in the TGBS and the UPDRS part III were scored in the clinical setting. Fallers were categorized if the patient experienced at least one fall in the prior six-month period. Results: Thirty-five patients were categorized as fallers. When comparing PD fallers and PD non-fallers, a subscore comprising a sum with ‘walk stance’ and ‘nudge on sternum’ in the TGBS showed a significant difference. Total UPDRS part III score indicated a significant difference during the medication ON period, whereas the difference was insignificant during the medication OFF period. The presence of dyskinesia or freezing of gait was not different. In addition, ‘walk stance’ only in the TGBS showed a significant difference between PD fallers and AP fallers. Conclusions: We concluded that ‘walk stance’ and ‘nudge on sternum’ in the TGBS may be useful for evaluating factors associated to falling in PD. ‘Walk stance’ item merits inclusion into routine assessment in PD in addition to UPDRS part III.

Mechanics and control of the flat versus normal foot during the stance phase of walking

Objective. To compare walking stance phase rearfoot and forefoot motion, ankle joint moments and extrinsic foot muscle EMG profiles between normal and pes planus feet. Design. A cross-sectional comparative study. Background. Musculoskeletal conditions are often attributed to pes planus, in which motion is assumed to be excessive and the muscle control inadequate. However, many of the speculated differences in mechanics and control between the normal and the pes planus foot have not been quantified. Methods. Kinematic and kinetic data were obtained from video recordings of skin surface markers and a force plate, and EMG was recorded with surface electrodes. Analysis of variance was carried out to compare the group profiles. Results. In the pes planus group: the forefoot was less adducted ( P<.05) at toe-off, and total transverse plane range of motion, at 8° versus 10°, was less ( P<.01); the peak plantarflexor ankle moment at push-off was greater ( P<.05); the invertor moment was greater at foot flat ( P<.05); for the EMG profiles, activity early in stance, relative to the mean stance phase activity was higher ( P<.01) in tibialis anterior and lower ( P<.05) in the peronei, soleus and medial and lateral gastrocnemius. Conclusions. Despite reaching statistical significance, the group differences were small for the task of laboratory walking at a natural pace. The main implications of the differences were for restraint of motion. The expectations of excessive motion and muscle effort in the pes planus group were therefore not substantiated. Relevance Symptomatic pes planus subjects did not reveal the expected biomechanical differences from normal subjects. The underlying causes of symptoms were not identifiable.

Equinus Deformity as a Compensatory Mechanism for Ankle Plantarflexor Weakness in Cerebral Palsy

A theory for equinus gait in cerebral palsy (CP) is that the strong plantarflexors prevent the weak dorsiflexors from achieving dorsiflexion, thereby causing the ankle to be in a plantarflexed position. Recent work has indicated that both the ankle dorsiflexors and plantarflexors are weak. The purpose of this research was to theoretically and experimentally demonstrate that equinus deformity gait could be a compensatory strategy for plantarflexor weakness. It was hypothesized that children with CP utilize an equinus position during gait as a consequence of their weakness. A two-dimensional, sagittal plane model estimating plantarflexor forces through the Achilles tendon was developed. Five able-bodied (AB) children were tested utilizing heel-toe and progressively increasing toe walking strategies. Four children with CP were tested as they walked using their equinus gait. Results demonstrated that AB children assuming the toe walking stance progressively reduced the plantarflexor force when compared to their heel-toe walking trials. However, their toe walking strategy could not reduce the plantarflexor force level to that of the children with CP during the gait cycle. It was concluded that the equinus deformity posture complemented the CP children's plantarflexor weakness. Therefore, by implementing a concomitant strategy to maintain a reduced force state, equinus deformity could be used as a compensatory mechanism for individuals with plantarflexor weakness.

Modeling three-dimensional sculptures of australopithecines (Australopithecus afarensis) for the Museum of Natural History of Vienna (Austria): the post-cranial hypothesis

In March 1999, E. Daynes, a sculptor specializing in fossil hominid reconstruction, asked C. Berge to take over the scientific supervision of the reconstruction of two australopithecine post-crania. The heads had been modeled from two skulls found in Hadar (AL 444-2, AL 417). The sculptures were to be represented in a walking stance. The female proportions (AL 417) are estimated from the skeleton of ‘Lucy’ (AL 288), and the male proportions (AL 444-2) extrapolated from the female ones. Biomechanical and anatomical data (comparison with great apes and humans) are used to reconstruct both dynamic equilibrium and muscular systems. The reconstruction suggests that the fossils moved the pelvis and shoulders extensively when they walked. The hindlimb muscles (such as adductors, gluteal muscles and calf) are fleshy and not or very little tendinous. As indicated by the Laetoli step prints (belonging to a close and contemporaneous species), the foot is adducted during the walk and the support is internal just before take off. In spite of inevitable approximations, such a reconstruction appears to be particularly helpful to bring out morphological and functional traits of the first hominids which are both close to and different from modern humans.

Forelimb joint moments and power during the walking stance phase of horses

Abstract Objective To calculate normative joint moments of force and power for the forelimb of walking horses as a benchmark against which to compare these mechanical variables in horses with specific lameness. Animals 4 Dutch Warmblood horses with no recent history of lameness. Procedure Horses were walked by hand through the test area, and data from 5 walking trials were collected for each horse. Two camera views were combined with vertical and craniocaudal ground reaction forces to calculate net moments of force in the sagittal plane across the carpal, metacarpophalangeal (fetlock), and distal interphalangeal (coffin) joints during the stance phase of the forelimb. Mechanical power was calculated as the product of net joint moment and the joint's angular velocity. Results During the early part of the stance phase, the carpal joint had oscillating periods of energy generation and absorption against a predominant flexor moment, then an absorption phase at the end of the stance phase, as the carpus flexed into swing against an extensor moment. The fetlock absorbed energy in the early part of the stance phase, then the terminal part was marked by a large generation of energy across the joint. A flexor moment was measured at the coffin joint throughout the stance phase, and this coincided with a long phase of energy absorption followed by a short phase of generation for push-off. Conclusion Consistency of the power data indicates that typical profiles of work exist for each of the joints (carpus, fetlock, and coffin). Clinical Relevance Detection of changes to these profiles of work may contribute to diagnosis of specific lameness conditions.(Am J Vet Res 1998;59:609–614)

Traumatic dislocation of the tibialis posterior tendon

Dislocation of the tibialis posterior tendon (TPT) at the ankle level is very rare. The difficult clinical diagnosis frequently causes delay of surgical treatment. Loss of TPT function impairs normal posture and walking stance because of the acquired flat foot deformity. English literature has reported only 16 cases of traumatic TPT dislocation. 1,3–10 Significance of magnetic resonance imaging (MRI) has not been stressed so far. We present a case of TPT dislocation with its MRI findings.