Kinematic patterns of participants with a below-knee prosthesis stepping over obstacles of various heights during locomotion

The focus of this paper was to examine the lead limb preference and the kinematic patterns of the lead limb of participants with a unilateral below-knee prosthesis when stepping over obstacles of different heights. Firstly, ten unilateral below-knee amputees stepped over obstacles of three different heights placed in their walking path to determine if they had a lead limb preference. Five of the ten participants demonstrated a sound limb lead preference, two participants showed a prosthetic limb lead preference and three showed no preference at all. Seven of these participants subsequently stepped over obstacles of six different heights leading with their sound or prosthetic limb as observed in the first experiment, while whole body kinematic data were collected. Relative joint angles of the stance and swing limb were calculated when the swing limb was over the obstacle. Swing hip elevation and hip and knee flexion increased as functions of obstacle height. Stance limb hip flexion, knee flexion and (on the sound side) ankle plantarflexion increased slightly with increasing obstacle height, but stance limb hip elevation did not. Therefore, it appears that these stance limb modulations served to position the pelvis further back from the obstacle as obstacle height increased. The posterior shell of the prosthetic socket limited residual limb swing knee flexion, and the increased ankle dorsiflexion seen on the lead sound side was not present on the lead prosthetic side. These limitations were associated with increased swing prosthetic foot angle and increased stance ankle plantarflexion. These results provide insights into the adaptability of the locomotor system, and have implications for lower extremity prosthetic design and amputee rehabilitation.     

Threshold of equinus which alters biomechanical gait parameters in children

The main aim of this study was to define the threshold angle of equinus beyond which significant changes in 3D lower limb kinematics and kinetics occur in typically developing children and to describe these changes.A customized orthosis was fitted on the right ankle of 10 typically developing children and was adjusted to +10° ankle dorsiflexion, 0°, ?10°, ?20° plantarflexion and maximum plantarflexion. Gait was analyzed using an optoelectronic system. A gait velocity of 1 m/s was imposed.Most of the kinematic and kinetic changes were significantly altered from the ?10° condition. In the sagittal plane, the results showed increased knee flexion at initial contact, increased knee flexion or hyperextension in stance, increased hip flexion at initial contact and increased anterior pelvic tilt. Other changes included increased knee varus, reduced hip adduction and more internal foot progression. The ankle plantarflexion moment was bi-phasic during stance, peak ankle power generation was reduced, peak knee extension moment was decreased and hip extension moments increased. On the contralateral side, there was a significant increase in ankle plantarflexion at initial contact and a significant decrease in knee flexion during swing phaseat maximum plantarflexion.Although slight modifications occurred for smaller degrees of equinus, the results suggest that significant kinematic and kinetic changes occurred during gait in both limbs from 10° of plantarflexion. The results of this study also provide some indications regarding the primary causes of gait deviations and secondary compensatory strategiesin children with a clinical dorsiflexion limitation.     

Ankle–foot orthosis with dorsiflexion resistance using spring-cam mechanism increases knee flexion in the swing phase during walking in stroke patients with hemiplegia

BackgroundAnkle–foot orthoses with plantarflexion resistance (AFO-Ps) improve knee flexion in the stance phase on the paretic side in patients with hemiparesis. However, AFO-Ps decrease ankle power generation in the late stance phase and do not improve the knee flexion in the swing phase based on insufficient push-off at the late stance, resulting in lower toe clearance.Research questionThis study sought to investigate the effect of an AFO with dorsiflexion resistance, which was implemented by our developed device with spring–cam mechanism attached to the AFO-P (Gait Solution; Pacific Supply Co., Ltd., Japan), on kinetics and kinematics in the lower limb during gait in patients with hemiparesis.MethodsEleven patients with hemiparesis due to stroke walked on a 7-m walkway at a self-selected comfortable pace in the following conditions: (a) walking using the AFO-P with the proposed device with a spring–cam mechanism (AFO-PCAM), (b) walking using the AFO-P without our device (AFO-P), and (c) walking using no device (barefoot condition). Gait kinematics and kinetics were collected using a three-dimensional motion analysis system and four ground-reaction force plates. Changes in all parameters from the barefoot to AFO-PCAM and AFO-P conditions were compared using the Wilcoxon signed-rank test.ResultsIn the AFO-PCAM condition, decrease in the maximum ankle power generation in the late-stance phase was significantly smaller than that in the AFO-P condition (p = 0.041). We noted a significant higher change in knee flexion in the paretic swing phase in the AFO-PCAM condition relative to that in the AFO-P condition (p = 0.016). The effect size for the comparisons of change was large (r ≧ 0.5).SignificanceOur device facilitated the realization of the ankle plantarflexion power in the late-stance phase because of dorsiflexion resistance, increasing the knee flexion angle during the swing phase.     

Lower extremity kinematics and kinetics during level walking and stair climbing in subjects with triple arthrodesis or subtalar fusion

The purpose of this study was to identify the kinematic and kinetic strategies used by patients with unilateral triple arthrodesis or subtalar fusion during level walking, stair ascent, stair descent and to determine the influence of these different conditions on kinematics and kinetics. Nine subjects with unilateral triple or subtalar fusion and five normal control subjects were recruited for this experiment. Temporal distance, kinematic and kinetic data were collected using a six camera 3-D motion analysis system and a custom fabricated set of stairs with five steps; the second and third steps were each instrumented with one force platform. During level walking, affected limbs lost all of the plantarflexion at the ankle joint during push-off and showed greater knee flexion angle during the same period of stance. During stair ascent, affected limbs showed a different movement pattern at the knee, a greater knee flexion angle during the whole stance phase and a near zero degree of plantarflexion angle during the forward continuance (FCN) phase. During descent, affected limbs showed a greater knee flexion angle during the whole stance phase and less ankle dorsiflexion angle during the same period of stance phase. At the ankle, peak moment and power values were significantly different between the affected side and the limbs of the control subjects during level walking in the push-off phase, stair ascent in the FCN phase, and stair descent in the weight acceptance (WA) phase, where the affected limbs had a lower plantarflexion moment and power values.     

Postoperative gait analysis and hip muscle strength in patients with pelvic ring fracture

The aims of present study were (1) to determine changes in kinematic and kinetic variables at 3 and 12 months after open reduction and internal fixation (ORIF) of pelvic ring fracture and (2) to determine the factor(s) associated with gait disorders that correlate with gait parameters measured at 12 months after surgery. Nineteen patients with pelvic ring fractures underwent ORIF and examined at 3 and 12 months postoperatively. The study also included a similar number of age-matched control subjects. Peak hip abduction angle, peak hip extension moment in the stance, peak hip abduction moment, and peak ankle plantarflexion moment at 3 months after ORIF were significantly lower than the respective control values. At 12 months, complete recovery was noted in peak hip abduction moment and peak ankle plantarflexion moment, whereas the recovery in peak hip abduction angle and peak hip extension moment in the stance was partial. The existence of neurological lesions and strength asymmetry of hip abductor and adductor at 3 months post-ORIF correlated with decreased peak hip abduction moment after ORIF. Our results highlighted characteristic gait patterns up to 12 months after ORIF for pelvic fracture, and these patterns correlated with neurological lesion and weakness of hip abductor and adductor muscles.     

Aging effects on postural responses to self-imposed balance perturbations

The present study investigated how young and older individuals organize their posture in response to self-induced balance perturbations evoked by oscillatory single limb movements. Eleven old (70.1+/-4.3 years) and nine young (20.1+/-2.4 years) participants performed repeatedly for 5s hip flexion/extension movements using full range of motion and maximum velocity. Two-dimensional joint kinematics (sampling rate: 60Hz), center of pressure (CoP) and EMG activity of tibialis anterior (TA), medial gastrocnemius (MGAS) rectus femoris (RF) and, semitendinosus (ST) in the stance limb were recorded and analysed. Cross-correlation function (CCF) analysis was used to identify the degree of coupling between the swinging limb (SL), center of gravity (CoG) and CoP motions. Old adults significantly limited SL, CoG and CoP range of anterior/posterior (A/P) motion in response to the forceful leg swinging. In the stance limb, significantly lower levels of ankle muscle activity resulted in reduced hip and knee joint excursions and increased ankle instability. By contrast, young performers produced sufficient ankle muscle activity to stabilize the foot to the ground while progressively increasing joint range of motion from the ankle to the hip. Center of pressure and SL movements were strongly correlated in an anti-phase relationship in both age groups. In older adults, however, the relationship between CoG-SL and CoG-CoP movements was neither strong nor synchronous, reflecting a weaker coupling and lack of coordination between component movements. It is concluded that insufficient ankle muscle activity, central integration deficits and increased anxiety to postural threat are important factors implicated for the weaker postural synergies and freezing of degrees of freedom seen in the elderly during performance of single limb oscillations.     

Gait characteristics of individuals with transtibial amputations walking on a destabilizing rock surface

Individuals with transtibial amputation (TTA) have a high incidence of falls during walking. Environmental factors, such as uneven ground, often play a contributing role in these falls. The purpose of this study was to quantify the adaptations TTA made when walking on a destabilizing loose rock surface. In this study, 13 young TTA walked over a rock surface and level ground at four controlled speeds. Subjects successfully traversed the rock surface by adopting a conservative gait characterized by shorter and wider steps. They also took shorter steps with their prosthetic limbs and exhibited greater variability in foot placement when stepping onto their intact limb. Between-limb differences in step length and width variability increased at faster walking speeds. TTA increased hip and knee flexion during initial stance, which contributed lowering the whole-body center of mass. TTA also increased hip and knee flexion during swing, enabling them to significantly increase their toe clearance on the rock surface compared to level ground. Toe clearance on the prosthetic side was aided by increased ipsilateral hip flexion. The results suggest that TTA were able to adapt their gait to overcome the challenge imposed by the rock surface. These adaptations were asymmetric and initiated proximally.     

Lower limb joint-specific contributions to standing postural sway in persons with unilateral lower limb loss

BackgroundIndividuals with lower limb loss are at an increased risk for falls, likely due to impaired balance control. Standing balance is typically explained by double- or single-inverted pendulum models of the hip and/or ankle, neglecting the knee joint. However, recent work suggests knee joint motion contributes toward stabilizing center-of-mass kinematics during standing balance.Research QuestionTo what extent do hip, knee, and ankle joint motions contribute to postural sway in standing among individuals with lower limb loss?MethodsForty-two individuals (25 m/17f) with unilateral lower limb loss (30 transtibial, 12 transfemoral) stood quietly with eyes open and eyes closed, for 30 s each, while wearing accelerometers on the pelvis, thigh, shank, and foot. Triaxial inertial measurement units were transformed to inertial anterior-posterior components and sway parameters were computed: ellipse area, root-mean-square, and jerk. A state-space model with a Kalman filter calculated hip, knee, and ankle joint flexion-extension angles and ranges of motion. Multiple linear regression predicted postural sway parameters from intact limb joint ranges of motion, with BMI as a covariate (p < 0.05).ResultsWith eyes open, intact limb hip flexion predicted larger sway ellipse area, whereas hip flexion and knee extension predicted larger sway root-mean-square, and hip flexion, knee extension, and ankle plantarflexion predicted larger sway jerk. With eyes closed, intact limb hip flexion remained the predictor of sway ellipse area; no other joint motions influenced sway parameters in this condition.SignificanceHip, knee, and ankle motions influence postural sway during standing balance among individuals with lower limb loss. Specifically, increasing intact-side hip flexion, knee extension, and ankle plantarflexion motion increased postural sway. With vision removed, a re-weighting of lower limb joint sensory mechanisms may control postural sway, such that increasing sway may be regulated by proximal coordination strategies and vestibular responses, with implications for fall risk.     

Obstacle crossing in lower limb amputees

OBJECTIVE: To study limitations in function and adjustment strategies in lower limb amputees during obstacle crossing. DESIGN: Observational cohort study. SUBJECTS: Transfemoral and transtibial amputees and able-bodied control subjects. METHODS: In a motion analysis laboratory unimpeded and obstacle crossing runs were performed. The subjects stepped over an obstacle of 0.1m height and thickness and 1m width. Outcome measures were gait velocity, hip, knee and ankle joint angles and leading limb preference. RESULTS: Whereas able-bodied and transtibial subjects demonstrated an increase in knee flexion during obstacle crossing compared to unimpeded walking, in transfemoral amputees the opposite was seen, namely a decrease in knee flexion. The lack of knee strategy in transfemoral amputees was compensated by circumduction at the hip on the prosthetic side and plantar flexion of the non-affected ankle. Transtibial amputees preferred to cross the obstacle with the prosthetic limb first, while transfemoral amputees preferred the non-affected limb. CONCLUSION: The different leading limb strategy in transfemoral and transtibial amputees could be explained by the restricted flexion and propulsion properties of the prosthetic knee. Training of obstacle crossing tasks during rehabilitation and improvement of prosthetic design may contribute to safe obstacle crossing.     

Comparison of transtibial amputee and non-amputee biomechanics during a common turning task

The biomechanics of amputee turning gait has been minimally studied, in spite of its integral relationship with the more complex gait required for household or community ambulation. This study compares the biomechanics of unilateral transtibial amputees and non-amputees completing a common turning task. Full body gait analysis was completed for subjects walking at comparable self-selected speeds around a 1m radius circular path. Peak internal and external rotation moments of the hip, knee and ankle, mediolateral ground reaction impulse (ML GRI), peak effective limb length, and stride length were compared across conditions (non-amputee, amputee prosthetic limb, amputee sound limb). Amputees showed decreased internal rotation moments at the prosthetic limb hip and knee compared to non-amputees, perhaps as a protective mechanism to minimize stress on the residual limb. There was also an increase in amputee sound limb hip external rotation moment in early stance compared to non-amputees, which may be a compensation for the decrease in prosthetic limb internal rotation moment during late stance of the prior step. ML GRI was decreased for the amputee inside limb compared to non-amputee, possibly to minimize the body's acceleration in the direction of the turn. Amputees also exhibited a shorter inside limb stride length compared to non-amputees. Both decreased ML GRI and stride length indicate a COM that is more centered over the base of support, which may minimize the risk of falling. Finally, a longer effective limb length was found for the amputee inside limb turning, possibly due to excessive trunk shift.     

Assessment of biomechanical deficits in individuals with a trans-tibial amputation during level gait using one-dimensional statistical parametric mapping

BackgroundMost previous studies reported biomechanical deficits in individuals with a trans-tibial amputation (TTA) during gait using zero-dimensional analyses. However, these analyses do not allow to precisely determine during which part of the gait cycle these deficits occur. There is a need to use more appropriate methods to map the differences, such as one-dimensional statistical parametric mapping.Research questionWhat are the most relevant phases of the gait cycle during which the biomechanical deficits in TTA occur?MethodsEight TTA and 15 healthy counterparts (CON) underwent one biomechanical gait analysis. Pelvis, hip, knee and ankle kinematics, total support moment (TSM) and gastrocnemius lateralis, vastus lateralis and tibialis anterior muscle activity were compared between the amputated (AmLL), the intact (InLL) and the control (CnLL) lower limbs using one-dimensional statistical parametric mapping.ResultsMore ankle dorsiflexion and knee flexion were observed for the AmLL compared to the InLL and CnLL (ankle only) from the end of the stance phase to the beginning of the swing phase. Less knee flexion was also found for the AmLL during early stance phase. More pelvis posterior tilt and rotation toward the contralateral limb was observed during most of the gait cycle for the AmLL compared to the InLL. TSM was smaller for the AmLL compared to the CnLL during early stance phase.SignificanceUsing a one-dimensional statistical parametric mapping approach for TTA gait analysis, this study provides novel insights on their biomechanical gait deficits compared to CON. Greater reliance on the InLL was observed in TTA as suggested by the asymmetric kinematic and kinetic profiles.     

The relationship between supination resistance and the kinetics and kinematics of the foot and ankle during gait

BackgroundClinical tests of foot posture and mobility are not strongly related to the dynamic kinematics of the foot during gait. These measures may be more directly related to foot and ankle kinetics. The supination resistance test (SRT) is a clinical test that may more directly measure forces acting on the weightbearing foot to provide clinicians with insight about the loading of foot structures.Research QuestionWhat is the relationship between the SRT in relaxed calcaneal stance and in single-leg-stance and the kinetics and kinematics of the foot and ankle during gait?Methods10 healthy adults between the ages of 18 and 65 were recruited to participate in this study. Three-dimensional motion analysis was performed using the Oxford Foot Model during gait. The results of the SRT were compared with peak midfoot and ankle joint moments, power generation and absorption, joint angles, and peak angular velocities and accelerations. Correlation coefficients were calculated to assess the strength of relationships between these variables and the SRT.ResultsThe SRT demonstrated significant relationships with several variables. In relaxed calcaneal stance, the SRT was inversely related to maximum midfoot pronation moments (r = −0.51), maximum midfoot plantarflexion moments (rho = −0.71), and peak midfoot power generation (r = −0.61). In single-leg-stance, the SRT was significantly related to maximum midfoot plantarflexion moments (rho = −0.55) and peak midfoot power generation (r = −0.47).SignificanceThe SRT is significantly associated to several kinetic variables that quantify midfoot loading during gait. Interventions that decrease supination resistance may have the potential to increase midfoot power generation.     

Uphill and downhill walking in unilateral lower limb amputees

OBJECTIVE: To study adjustment strategies in unilateral amputees in uphill and downhill walking. DESIGN: Observational cohort study. SUBJECTS: Seven transfemoral, 12 transtibial unilateral amputees and 10 able-bodied subjects. METHODS: In a motion analysis laboratory the subjects walked over a level surface and an uphill and downhill slope. Gait velocity and lower limb joint angles were measured. RESULTS: In uphill walking hip and knee flexion at initial contact and hip flexion in swing were increased in the prosthetic limb of transtibial amputees. In downhill walking transtibial amputees showed more knee flexion on the prosthetic side in late stance and swing. Transfemoral amputees were not able to increase prosthetic knee flexion in uphill and downhill walking. An important adjustment strategy in both amputee groups was a smaller hip extension in late stance in uphill and downhill walking, probably related with a shorter step length. In addition, amputees increased knee flexion in early stance in the non-affected limb in uphill walking to compensate for the shorter prosthetic limb length. In downhill walking fewer adjustments were necessary, since the shorter prosthetic limb already resulted in lowering of the body. CONCLUSION: Uphill and downhill walking can be trained in rehabilitation, which may improve safety and confidence of amputees. Prosthetic design should focus on better control of prosthetic knee flexion abilities without reducing stability.     

Elderly unilateral transtibial amputee gait on an inclined walkway: a biomechanical analysis

The greatest population of amputees in developed nations are elderly dysvascular transtibial amputees. Conventional prostheses, e.g. the solid ankle cushioned heel (SACH) foot, create difficulties in walking on inclines. The aim of this study was to analyse the gait characteristics of elderly amputees walking on an incline, through quantitative three-dimensional biomechanical analysis, by comparing them to age-matched controls. Participants walked up and down an inclined (5 degrees) instrumented walkway at a self-selected pace. A Vicon System 370 was used to acquire gait data, including temporo-spatial characteristics, ground reaction forces (GRF), electromyography (EMG), kinematics, and kinetics of the lower limb. Compared to the age-matched controls, the amputees demonstrated reduced speed, knee and hip range of motion, hip moments, vertical GRF, along with increased amplitude and periods of muscle activation. The residual limb also had shorter single support stance phase, small stance phase knee moments, and the smallest moments and powers. These differences demonstrate instability in stance of the residual limb. The sources of this instability include the prosthesis' limited range of ankle motion and ankle power generation, coupled with the residual limb's limited proprioception and tolerance of force. For these amputees to regain a gait pattern equivalent to their able-bodied counterparts on inclined walkways, they must be equipped with a prosthesis that has a full range of ankle motion and active power generation at the ankle. Prosthesis design and rehabilitation training should also improve the proprioception of their residual limb and increase their tolerance of force through the residual limb.     

Hip external rotation stiffness and midfoot passive mechanical resistance are associated with lower limb movement in the frontal and transverse planes during gait

BackgroundHip external rotation stiffness, midfoot passive mechanical resistance and foot alignment may influence on ankle, knee and hip movement in the frontal and transverse planes during gait.Research questionAre hip stiffness, midfoot mechanical resistance and foot alignment associated with ankle, knee and hip kinematics during gait?MethodsHip stiffness, midfoot mechanical resistance, and foot alignment of thirty healthy participants (18 females and 12 males) with average age of 25.4 years were measured. In addition, lower limb kinematic data during the stance phase of gait were collected with the Qualisys System (Oqus 7+). Stepwise multiple linear regressions were performed to identify if hip stiffness, midfoot torque, midfoot stiffness and foot alignment were associated with hip and knee movement in the transverse plane and ankle movement in the frontal plane with α = 0.05.ResultsReduced midfoot torque was associated with higher hip range of motion (ROM) in the transverse plane (r² = 0.18), reduced hip stiffness was associated with higher peak hip internal rotation (r² = 0.16) and higher ROM in the frontal plane (r² = 0.14), reduced midfoot stiffness was associated with higher peak knee internal rotation (r² = 0.14) and increased midfoot torque and midfoot stiffness were associated with higher peak knee external rotation (r² = 0.36).SignificanceThese findings demonstrated that individuals with reduced hip and midfoot stiffness have higher hip and knee internal rotation and higher ankle eversion during the stance phase of gait. On the other hand, individuals with increased midfoot torque and stiffness have higher knee external rotation. These relationships can be explained by the coupling between ankle movements in the frontal plane and knee and hip movements in the transverse plane. Finally, this study suggests that midfoot passive mechanical resistance and hip stiffness should be assessed in individuals presenting altered ankle, knee and hip movement during gait.     

Anticipatory locomotor adjustments of the trail limb during surface accommodation

This paper explores anticipatory locomotor adjustments of the trail limb when stepping up to a new level. The kinematics and kinetics of the trail limb for nine subjects were compared across level gait and surface accommodation. The largest generation of new rotational energy was found at the trail ankle, during the latter part of stance (i.e. ankle 'push-off'). Accelerations of the head, arms and trunk (HAT) and foot segments during the same phase indicate that the ankle power acted to push the body and lead limb up onto the new level and drive the foot upwards at toe-off. The shank was more vertical at toe-off to ensure that the ankle energy would drive the limb upwards, rather than forward into the surface. The vertical hip translation energy increased over 300%, acting to pull upwards on the hip to increase trail limb elevation. The increased hip translational energy could be due to extension of the lead limb after it was placed on the surface and/or the piston-like drive of the increased rotational energy at the trail ankle during late stance. The findings add to the knowledge of whole body coordination strategies during anticipatory locomotor adjustments when the entire body is raised to a new level.     

Outdoor dynamic subject-specific evaluation of internal stresses in the residual limb: hydraulic energy-stored prosthetic foot compared to conventional energy-stored prosthetic feet

The prosthetic foot plays an important role in propelling, breaking, balancing and supporting body loads while the amputee ambulates on different grounds. It is therefore important to quantify the effect of the prosthetic foot mechanism on biomechanical parameters, in order to prevent pressure ulcers and deep tissue injury. Our aim was to monitor the internal stresses in the residuum of transtibial amputation (TTA) prosthetic-users ambulating on different terrains, which the amputees encounter during their daily activities, i.e. paved floor, grass, ascending and descending stairs and slope. We specifically aimed to compare between the internal stresses in the TTA residuum of amputees ambulating with a novel hydraulic prosthetic foot compared to conventional energy storage and return (ESR) prosthetic feet. Monitoring of internal stresses was accomplished using a portable subject-specific real-time internal stress monitor. We found significant decrease (p<0.01) in peak internal stresses and in the loading rate of the amputated limb, while walking with the hydraulic foot, compared to walking with ESR feet. The loading rate calculated while ambulating with the hydraulic foot was at least three times lower than the loading rate calculated while ambulating with the ESR foot. Although the average decrease in internal stresses was ≈ 2-fold larger when replacing single-toe ESR feet with the hydraulic foot than when replacing split-toed ESR feet with the hydraulic foot, the differences were statistically insignificant. Our findings suggest that using a hydraulic prosthetic foot may protect the distal tibial end of the TTA residuum from high stresses, therefore preventing pressure-related injury and pain.     

Compensatory sagittal plane ankle gait mechanics: Are they present in patients with a weak or stiff hip?

IntroductionSimulations suggest that subjects with reduced hip range of motion (ROM) and/or weakness can achieve more normal walking mechanics through compensations at the ankle. The aims of this study were to assess whether subjects with reduced hip ROM (Stiff hip) or hip flexor weakness (Weak hip) exhibit ankle compensations during walking and investigate redistribution of power in the lower extremity joints.MethodsRetrospective gait data were reviewed (IRB-approved hip registry). Preoperative kinematic/kinetic walking data were collected in patients with: adolescent hip dysplasia (AHD), femoral acetabular impingement (FAI), and Legg-Calvé Perthes disease (Perthes). AHD patients with significantly weak hip flexors on their affected side were included (Weak hip group). The Gait Profile Score (GPS) was calculated on the affected side of the FAI and Perthes groups to identify patients who had a Stiff hip. Patients who had undergone a hip arthrodesis (Fusion) were also included (Stiff hip group). Ankle kinematics/kinetics were compared to healthy participants (Control). The total positive work of sagittal plane hip, knee and ankle power were compared along with the distribution of power.ResultsPatients in the Weak/Stiff hip groups did not walk with greater ankle plantarflexion, peak push-off power or positive ankle work on their affected sides compared to Control. Ankle work contribution (percentage of total positive work) on the affected or unaffected sides was greater in the Perthes and Hip Fusion patients compared to Control. Significant gait abnormalities on the unaffected side were observed.ConclusionsPatients with a weak or stiff hip did exhibit altered ankle mechanics during walking. Greater percent ankle work contribution appeared to correspond with hip stiffness. In patients with hip pathology the redistribution of power among the lower extremity joints can highlight the importance of preserving ankle function.     

Biomechanical analysis of gait waveform data: exploring differences between shod and barefoot running in habitually shod runners

The aim of this study was to utilise one-dimensional statistical parametric mapping to compare differences between biomechanical and electromyographical waveforms in runners when running in barefoot or shod conditions.Fifty habitually shod runners were assessed during overground running at their current 10-km race running speed. Electromyography, kinematics and ground reaction forces were collected during these running trials. Joint kinetics were calculated using inverse dynamics. One-dimensional statistical parametric mapping one sample t-test was conducted to assess differences over an entire gait cycle on the variables of interest when barefoot or shod (p < 0.05).Only sagittal plane differences were found between barefoot and shod conditions at the knee during late stance (18–23% of the gait cycle) and swing phase (74–90%); at the ankle early stance (0–6%), mid-stance (28–38%) and swing phase (81–100%). Differences in sagittal plane moments were also found at the ankle during early stance (2, 4–5%) and knee during early stance (5–11%). Condition differences were also found in vertical ground reaction force during early stance between (3–10%).An acute bout of barefoot running in habitual shod runners invokes temporal differences throughout the gait cycle. Specifically, a co-ordinative responses between the knee and ankle joint in the sagittal plane with a delay in the impact transient peak; onset of the knee extension and ankle plantarflexion moment in the shod compared to barefoot condition was found. This appears to affect the delay in knee extension and ankle plantarflexion during late stance. This study provides a glimpse into the co-ordination of the lower limb when running in differing footwear.     

The relative contributions of the prosthetic and sound limb to balance control in unilateral transtibial amputees

In unilateral transtibial amputees maintenance of standing balance is compromised due to the lack of active ankle control in the prosthetic limb. The purpose of this study is to disentangle the contribution of the prosthetic and sound limb to balance control following waist-pull perturbations. We compared the contribution of the hip and ankle joints to balance control of 15 unilateral transtibial amputees and 13 able-bodied controls after been externally perturbed through release of a pulling force. Perturbations were applied in four different directions. Outcome measure was the proportion of joint moment integrated over time generated by the hip and ankle joints in order to restore static stability after perturbation. Analyses revealed that perturbations in backward/forward direction were recovered mainly by the ankle strategy. The amputees compensated for the absence of active ankle control in the prosthetic limb by increasing the ankle moment in the sound limb. Interestingly, the passive properties of the prosthetic foot contributed to balance control, which has important implications for prosthetic fitting and standing stability in lower limb amputees. Amputees and controls resisted perturbations in medio-lateral direction by generating the necessary hip moments. Finally, these findings are discussed with respect to prosthetic design and rehabilitation processes.