Simultaneous, bilateral, and three-dimensional gait analysis of elderly people without impairments

OBJECTIVE: The main objectives of this study were to determine if the right and left lower limbs in the gait of elderly people developed similar muscle moment and power patterns and to determine whether their associated mechanical energies were different during two consecutive gait cycles. DESIGN: A total of 18 able-bodied male subjects aged 71 +/- 6.8 yrs participated in this study. Data were collected using three Optotrak position sensors and two AMTI force platforms. RESULTS: The peak muscle powers were very similar in the sagittal plane and reflected gait symmetry, except for greater and significant differences produced by the hip extensors. Differences in the frontal and transverse planes were mainly attributed to the actions taken by the muscles, leading the lower limbs to compensate and to dynamically balance and propel the body forward during two consecutive gait cycles. In terms of mechanical energy, 13% greater positive work was done in the left limb and was associated with asymmetrical behavior of the lower limbs to propel the body forward. The total negative work was similar for both limbs, and substantial work was done in the frontal plane by the hip, indicating the role of muscle activity in this plane to control the pelvis and trunk against gravitational forces. CONCLUSIONS: In addition to the importance of a balance-control function in the gait of healthy, elderly subjects, muscle activity made an important contribution to propelling the body forward. Gait asymmetry in elderly subjects seems to be related to different degrees of energy generated by the lower limbs for the propulsion function, whereas both limbs contribute similarly to the balance-control function.     

Lower limb muscle power relationships in bilateral able-bodied gait.

OBJECTIVE: The purpose of this study was to test the hypothesis that limb propulsion is mainly associated with the interaction of a number of muscle power bursts developed throughout the stance phase and that the control actions are mainly achieved by the contralateral limb through different power-burst interactions. We also hypothesized that the power activities of the propulsion limb would be related to those of the control limb. DESIGN: Sixty gait trials of 20 subjects with dominant right hands and right legs were chosen for analysis. Each trial represents a performance of an able-bodied gait. Data were assessed using an eight-camera, high-speed, video-based system synchronized to two force plates. The muscle powers and their related mechanical energies were calculated at each joint and in each plane of the lower limbs by use of an inverse dynamic technique. The Pearson correlation method was used to determine the relationships within each limb by use of the data identified by principal component analysis, whereas a canonical correlation analysis was performed to illustrate the interaction between the limbs. RESULTS: Gait propulsion was an activity initiated by the hip shortly after heel-strike and maintained throughout the stance phase. Control was the main task of the left limb as evidenced by the power absorption bursts at the hip and knee. The left limb power generations were generally secondary to control activities and were possibly involved in adjustments to correct the other limb's propulsion. Interlimb interaction further emphasized the functional relationship between forward progression and control tasks developed by each limb and highlighted the importance of the frontal and transverse plane actions during gait. CONCLUSION: These results do not support the hypothesis that the ankle was a major contributor to forward progression.     

External loading comparisons between able-bodied and below-knee-amputee children during walking.

The purpose of this investigation was to determine external loading variables that could describe any statistically significant differences between the limbs of below-knee-amputee (BKA) and able-bodied children. Eleven able-bodied children and four BKA children volunteered to participate in this investigation. Force platform data were collected for two consecutive foot falls during two experimental sessions. Significant external load differences existed between the prosthetic limbs and nonprosthetic limbs of BKA children and between limbs of the BKA and able-bodied children. The prosthetic limb generally displayed a subordinate role when compared to nonprosthetic and normal limbs. The nonprosthetic limbs displayed a dominant role when compared to the other limbs. These external loading characteristics of the prosthetic and nonprosthetic limbs may be a logical consequence of the morphologic and functional differences that exist between the groups. It was concluded that as long as the prosthetic limb functions differently from a normal limb, BKA children may have a difficult time walking the same as able-bodied children. It would appear to be advantageous to determine the most appropriate gait pattern for BKA children, given the influence of such factors as prosthetic design, construction, and alignment, rehabilitation, and joint loading.     

Muscle adaptation patterns of children with a trans-tibial amputation during walking

BACKGROUND: Many studies have shown that trans-tibial amputation involves modifications of resultant muscle patterns during gait. However, these experiments did not estimate the contribution of simultaneous agonist and antagonist muscle action (co-contraction) during gait tasks. Diminution of co-contraction could create joint instability and, thus, change joint integrity, which is particularly important in the etiology of degenerative diseases, such as osteoarthritis, present at the knees of amputated limbs, and particularly in non-amputated limbs. The purpose of this study was to determine if there is any difference in the production of co-contraction about the knee between able-bodied children and children with a trans-tibial amputation during gait. METHODS: Six children with a trans-tibial amputation vs. six able-bodied children paired for gender, age, weight and height participated in this study. Four one-way ANOVAs (P<0.05) were used to observe differences in resultant, agonist and antagonist moments, power, and co-contraction index during different phases of gait between able-bodied children limbs, the amputated and the non-amputated limbs of children with trans-tibial amputation. FINDINGS: Children with a trans-tibial amputation modified muscle patterns at their amputated limb and produced smaller co-contraction (P<0.05) during single limb support, for both the non-amputated and amputated limbs when compared to able-bodied children. INTERPRETATION: These results suggest that children with a trans-tibial amputation altered their muscle patterns to perform locomotion. These changes produced a diminution of co-contraction during single limb support for both the amputated and non-amputated limbs and, thus, could create joint instability.     

Co-contraction patterns of trans-tibial amputee ankle and knee musculature during gait

ABSTRACT: BACKGROUND: Myoelectric control of upper extremity powered prostheses has been used clinically for many years, however this approach has not been fully developed for lower extremity prosthetic devices. With the advent of powered lower extremity prosthetic components, the potential role of myoelectric control systems is of increasing importance. An understanding of muscle activation patterns and their relationship to functional ambulation is a vital step in the future development of myoelectric control. Unusual knee muscle co-contractions have been reported in both limbs of trans-tibial amputees. It is currently unknown what differences exist in co-contraction between trans-tibial amputees and controls. This study compares the activation and co-contraction patterns of the ankle and knee musculature of trans-tibial amputees (intact and residual limbs), and able-bodied control subjects during three speeds of gait. It was hypothesized that residual limbs would have greater ankle muscle co-contraction than intact and able-bodied control limbs and that knee muscle co-contraction would be different among all limbs. Lastly it was hypothesized that the extent of muscle co-contraction would increase with walking speed. METHODS: Nine unilateral traumatic trans-tibial amputees and five matched controls participated. Surface electromyography recorded activation from the Tibialis Anterior, Medial Gastrocnemius, Vastus Lateralis and Biceps Femoris of the residual, intact and control limbs. A series of filters were applied to the signal to obtain a linear envelope of the activation patterns. A co-contraction area (ratio of the integrated agonist and antagonist activity) was calculated during specific phases of gait. RESULTS: Co-contraction of the ankle muscles was greater in the residual limb than in the intact and control limbs during all phases of gait. Knee muscle co-contraction was greater in the residual limb than in the control limb during all phases of gait. CONCLUSION: Co-contractions may represent a limb stiffening strategy to enhance stability during phases of initial foot-contact and single limb support. These strategies may be functionally necessary for amputee gait; however, the presence of co-contractions could confound future development of myoelectric controls and should thus be accounted for.     

Quantifying varus thrust in knee osteoarthritis using wearable inertial sensors: A proof of concept

BackgroundVarus thrust during walking, visualized as excessive frontal plane knee motion during weight acceptance, is a modifiable risk factor for progression of knee osteoarthritis. However, visual assessment does not capture thrust severity and quantification with optical motion capture is often not feasible. Inertial sensors may provide a convenient alternative to optical motion capture. This proof-of-concept study sought to compare wearable inertial sensors to optical motion capture for the quantification of varus thrust.MethodsTwenty-six participants with medial knee osteoarthritis underwent gait analysis at self-selected and fast speeds. Linear regression with generalized estimating equations assessed associations between peak knee adduction velocity or knee adduction excursion from optical motion capture and peak thigh or shank adduction velocity from two inertial sensors on the lower limb. Relationships between inertial measures and peak external knee adduction moment were assessed as a secondary aim.FindingsBoth thigh and shank inertial sensor measures were associated with the optical motion capture measures for both speeds (P < 0.001 to P = 0.020), with the thigh measures having less variability than the shank. After accounting for age, sex, body mass index, radiographic severity, and limb alignment, thigh adduction velocity was also associated with knee adduction moment at both speeds (both P < 0.001).InterpretationAn inertial sensor placed on the mid-thigh can quantify varus thrust in people with medial knee osteoarthritis without the need for optical motion capture. This single sensor may be useful for risk screening or evaluating the effects of interventions in large samples.     

Quantifying complexity and variability in phase portraits of gait

Background

Injuries to the lower extremity often cause limitations to joint motion and alter movement patterns of limb segments during gait. We hypothesized that complexity and variability of limb segment motion during gait would increase in both limbs due to unilateral injury. Using simulated injury to generate asymmetric gait, we developed new methods to quantify changes in the complexity and variability of limb segment angular phase portraits.

Methods

To simulate reduced range of motion associated with knee injury, the right knee was constrained to full extension by an external brace. Thigh, shank and foot segment angular phase portraits were generated from 20 healthy male subjects walking for 3-minute trials with and without the brace. Using Fourier-based methods, complexity was quantified by the number of harmonic frequencies suitable for fitting the phase-portrait shape — with a larger number of harmonics indicating greater complexity. Variability was characterized by the drift and confidence area generated by the inter-cycle excursion of the phase-portrait centroid.

Findings

Significant differences were found in complexity and variability measures due to bracing. Phase-portrait shape complexity and variability increased in the right (braced) limb, compared to the unbraced condition; while only variability increased for the left (contralateral) limb during bracing.

Interpretation

These new methods proved successful at quantifying changes in the complexity and variability that have been visually observed in phase portraits during asymmetric gait. This work provides a method that can be incorporated into clinical assessments to provide quantifiable measures of more precise differences in gait dynamics.     

Biomechanical mechanisms of toe-out gait performance in people with and without knee osteoarthritis

Background

Toe-out gait modification (increased toe-out angle) has been proposed to decrease medial knee joint loading and slow disease progression in patients with knee osteoarthritis. However, the manner in which toe-out gait modification is performed is unknown. The purposes of this study were to assess the biomechanical strategies of achieving a toe-out gait, and to compare these strategies between older individuals with knee osteoarthritis and young, healthy individuals.

Methods

Lower limb biomechanics were evaluated for ten patients with knee osteoarthritis and for ten young, healthy individuals during treadmill walking. Two trials, consisting of natural gait followed by a ten degree increase in toe-out angle were performed. Transverse plane rotations of the thigh, shank and foot segments were calculated and compared between walking conditions and groups.

Findings

External rotation changes with toe-out were significantly different between the thigh and shank, and thigh and foot (P < 0.001), but not between the shank and foot (P = 0.48). External rotation at each segment was not significantly different (P > 0.05) between groups, with the exception of thigh rotation during natural gait (P = 0.04).

Interpretation

Current findings suggest that increased toe-out gait is primarily achieved through rotation of the shank and foot, with less contribution from the thigh, and those individuals with knee osteoarthritis perform a toe-out gait biomechanically similar to young, healthy individuals. Gait modification programs should address individuals' limitations, such as joint stiffness, to ensure functional performance of toe-out gait modification.     

Gait training with partial body weight support during overground walking for individuals with chronic stroke: a pilot study

Background

It is not yet established if the use of body weight support (BWS) systems for gait training is effective per se or if it is the combination of BWS and treadmill that improves the locomotion of individuals with gait impairment. This study investigated the effects of gait training on ground level with partial BWS in individuals with stroke during overground walking with no BWS.

Methods

Twelve individuals with chronic stroke (53.17 ± 7.52 years old) participated of a gait training program with BWS during overground walking, and were evaluated before and after the gait training period. In both evaluations, individuals were videotaped walking at a self-selected comfortable speed with no BWS. Measurements were obtained for mean walking speed, step length, stride length and speed, toe-clearance, durations of total double stance and single-limb support, and minimum and maximum foot, shank, thigh, and trunk segmental angles.

Results

After gait training, individuals walked faster, with symmetrical steps, longer and faster strides, and increased toe-clearance. Also, they displayed increased rotation of foot, shank, thigh, and trunk segmental angles on both sides of the body. However, the duration of single-limb support remained asymmetrical between each side of the body after gait training.

Conclusions

Gait training individuals with chronic stroke with BWS during overground walking improved walking in terms of temporal-spatial parameters and segmental angles. This training strategy might be adopted as a safe, specific and promising strategy for gait rehabilitation after stroke.

     

Hip hiking and circumduction: quantitative definitions

OBJECTIVE: To define and propose clinically useful quantitative measurements of hip hiking and circumduction using standard three-dimensional motion analysis techniques. DESIGN: We studied pelvic, hip, and thigh motions in 23 subjects with hemiparetic, stiff-legged gait as a result of stroke and compared these motions with those obtained from 23 able-bodied controls. RESULTS: We observed significantly increased hip abduction on the unaffected limb during stance, with simultaneous elevation of the affected side of the pelvis during swing. We define these differences as hip hiking and, thus, can quantify the degree to which hip hiking occurs by measuring the unaffected coronal hip angle and/or the coronal pelvic angle when the affected limb is in midswing. We also observed a greater than normal coronal thigh angle during midswing of the affected limb that we can use to quantitatively define circumduction. Of note, hip abduction during swing was not increased on the affected swing limb, compared with the control. CONCLUSIONS: Hip hiking can be defined precisely as unaffected coronal hip and/or pelvic angle when the affected limb is in midswing and circumduction can be defined as greater than normal coronal thigh angle during midswing of the affected limb. These precise definitions should allow us to better communicate and understand the implications of these gait patterns, and can serve as the basis for clinically meaningful quantitative assessment and outcome measurement tools.     

Effect of trunk inclination on lower limb joint and lumbar moments in able men during the stance phase of gait

Background

Though the effect of imposed trunk posture affects walking patterns little is known about the effect of natural orientation of the trunk on gait. The objectives of this study are to test if the lower limb joint and thoraco-lumbar moments are similar in subjects who maintain an average natural forward or backward trunk inclination during gait and verify if the lower limbs are equally affected.

Methods

Twenty-five young men were divided according to their natural backward or forward trunk inclination during level walking. Ankle, knee, hip and thoraco-lumbar moments were calculated by an inverse dynamic approach for the two limbs. A two-way ANOVA was performed on peak lower limb moments. A one-way ANOVA was performed on thoraco-lumbar peak moments.

Findings

There was a main effect for both trunk inclinations and lower limb sides but no interaction. For the forward leaners, the duration of hip extension moment was longer (P < 0.001) while the hip flexion moment was 1.3 times smaller (P < 0.001). Differences between the lower limb sides were noted in all joints but at push-off of the stance phase only. The two thoraco-lumbar extension moments were, respectively, 1.4 times higher for the forward leaners while the two flexion moments were approximately 1.4 times higher for the backward leaners.

Interpretations

The backward leaners propel themselves with a strong hip flexor activity at push-off while the forward leaners use their hip muscles throughout stance. These results support the idea that trunk inclinations and moment variations are associated with the type of walking patterns.     

Novel passive ankle-foot prosthesis mimics able-bodied ankle angles and ground reaction forces

Background: During gait, the human ankle both bends with ease and provides push-off forces that facilitate forward motion. The ankle is crucial for support, stabilization, and adapting to different slopes and terrains. Individuals with lower limb amputation require an ankle-foot prosthesis for basic mobility.Methods: Inspired by the role of the ankle-foot in an able-bodied gait, the 3D printed Compliant and Articulating Prosthetic Ankle (CAPA) foot was designed. It consists of four articulating components connected by torsion springs and produces forces that are dependent on the ankle angle. Using the Computer Assisted Rehabilitation Environment, able-bodied individuals walked wearing a prosthetic simulator with the Solid Ankle Cushioned Heel foot, Renegade® AT, and multiple versions of the CAPA. These versions test compliant vs. stiff, small vs. large rocker radius, and pretension vs. none. We hypothesized that the CAPA would have larger ankle range of motion, push-off forces, and braking forces.Findings: Compared to existing prostheses, the novel prosthesis exhibits greater and significantly different ankle range of motion and sagittal plane ground reaction forces than existing prostheses during gait. Nine out of ten individuals prefer the novel prosthesis to the existing prostheses, and there is a statistically significant difference in difficulty level ratings.Interpretation: By providing a personalizable and passive alternative to existing designs, the CAPA could improve the quality of life for the growing number of individuals living with limb loss in the United States and around the world.     

三维步态在脑卒中足下垂患者下肢节段协调性分析的应用

目的:运用三维步态分析系统分析脑卒中偏瘫足下垂患者的下肢关节协调性。方法:选取脑卒中偏瘫足下垂患者15例作为观察组,配对设计选取15例健康者作为对照组一和对照组二。采集2组受试者行走过程中的时空参数和运动学参数,通过绘制仰角曲线图和步态环图进行协调性分析。结果:观察组偏瘫侧与非偏瘫侧比较,步频、支撑期百分比,髋、膝关节活动度(ROM),最大踝背屈角度、小腿、足部仰角范围均减小(均P<0.01),步长、最大踝跖屈角度增加(均P<0.01);观察组偏瘫侧与对照组一比较,步速减慢、步长减短、步频减小、支撑期百分比延长(均P<0.01),髋、膝、踝关节ROM,最大踝背屈角度、大腿、小腿、足部仰角范围均减小(均P<0.01);观察组非偏瘫侧与对照组二比较,步速减慢、步长减短(均P<0.01),髋、膝、踝关节ROM,最大踝跖屈角度、大腿、小腿、足部仰角范围均减小(均P<0.01),支撑期百分比延长(P<0.01)。观察组偏瘫侧与对照组一比较,大腿仰角峰值出现时间延迟(P<0.01)。观察组偏瘫侧与对照组一比较以及观察组非偏瘫侧与对照组二比较,方差百分比(PV1)和PV1/PV2均减小(均P<0.01),PV2均增大(均P<0.01)。观察组偏瘫侧与非偏瘫侧分别与对照组一、对照组二比较,步态环图偏离正常水滴形态,表现为高度降低、尾部消失、扭曲。结论:步态环图可直观反映脑卒中偏瘫足下垂患者下肢协调性障碍,其中PV值的改变可能是其协调功能障碍的标志之一。     

The Effect of a Vertical Load on Gluteus Medius Activity and Gait Characteristics during Walking

[Purpose] The present study examined the activity and the gait characteristics of the gluteus medius and the trunk stability muscles during the stance phase of gait on level ground when a vertical load corresponding to 0%, 1%, or 2% of body weight was placed on the lower extremities during the swing phase of the gait. [Methods] The subjects were 40 young males aged between 21 and 30 years. The vertical load, corresponding to 0%, 1%, 2% of weight, which was measured with an electronic scale, was placed bilaterally 3 cm above from the upper part of the lateral malleous. Electrodes were symmetrically attached to the gluteus medius, erector spinae, external oblique, and internal oblique muscles. [Results] There were significant differences in the activities of the left gluteus medius, bilateral external oblique, and right internal oblique muscles among the vertical loads of 0%, 1%, and 2% during gait. [Conclusion] Increases in vertical load were accompanied by changes in the activities of the internal and external oblique abdominal muscles to ensure the stability of the trunk under the different loads. Gait was only possible with the activity of the gluteus medius muscle and the trunk muscles resisting the different vertical loads rather than activating other muscles of the lower extremities in terms of energy efficiency.Key words: Vertical load, Gait, Gluteus medius     

Improvement of gait by using orthotic insoles in patients with heel injury who received reconstructive flap operations

OBJECTIVE: To investigate the effect of orthotic insoles in heel injury patients who received reconstructive flap operations. DESIGN: Motion analysis and force platform data were collected in able-bodied subjects and patients with heel injuries during walking without and with the use of the total contact insole. Gait kinetics were collected for the hip, knee, and ankle joints and then compared with Student's t tests. RESULTS: Walking velocity and step length were decreased (P < 0.014 and P < 0.005) for patients not wearing the total contact insole. The affected limbs had longer double-support duration (14.8% of gait cycle, P < 0.037) and shorter single-support duration (34.5% of gait cycle, P < 0.045). Less hip power generation was noted for the affected limbs during both initial contact and preswing phases, 0.17 +/- 0.10 N-m/kg-m and 0.45 +/- 0.20 N-m/kg-m, as compared with that of the able-bodied subjects, 0.36 +/- 0.08 N-m/kg-m and 0.89 +/- 0.22 N-m/kg-m, respectively. Decreased ankle power generation was noted for the affected limbs (1.08 +/- 0.38 N-m/kg-m) during preswing phase as compared with the able-bodied subjects (2.24 +/- 0.33 N-m/kg-m). After fitting of the total contact insole, the affected limbs recovered to a gait pattern similar to that of the able-bodied subjects (P < 0.05). CONCLUSION: Asymmetry of gait pattern after heel injury resulted in altered gait kinetics. Gait symmetry could be recovered in these patients as the total contact insole provides weight acceptance, shock absorption, and cushioning effect for the reconstructed heels.     

Trunk biomechanics during walking after sub-acute stroke and its relation to lower limb impairments

BackgroundTrunk function and lower limb strength seem to be the primary predictors for functional independence in acute stroke patients. Gaining a better understanding of their relationship during walking aids in the identification of intrinsic trunk control deficits and underlying lower limb deficits resulting in compensatory trunk movements.MethodsFifty-seven subjects with stroke and 57 age- and gender-matched subjects without disability were included. Participants underwent an instrumented gait analysis with a standard total body Plug-In-Gait model, a clinical examination of the lower limbs based on range of motion, strength, muscle tone and several clinical assessment scales such as the Trunk Impairment Scale, Tinetti test and Functional Ambulation Categories. Spatiotemporal parameters and joint angular time profiles were compared between healthy adults and stroke survivors with severe and mild to moderate lower limb impairments. Spm1d was used to compare the joint angular time profiles between groups.FindingsTruncal deviations are present during hemiplegic walking, sub-acute stroke survivors walked with increased thoracic tilt, a neutral frontal position of the pelvis during stance, a pelvic hike during swing, and a more rotated position without crossing of the midline. Patients with more severe lower limb impairments had more pronounced deficits in truncal motion.InterpretationSetting accurate rehabilitation goals is of major importance during stroke, as well as understanding the underlying mechanisms and causes of the truncal impairments. Although more compensatory trunk deviations were seen in participants with severe lower limb impairments, they should not be considered as the sole contributor of trunk impairments during walking. Results of this study suggest that intrinsic trunk deficits during walking are also present after stroke.     

Sprint kinematics of athletes with lower-limb amputations.

OBJECTIVE: To determine and compare the kinematics of the sound and prosthetic limb in five of the world's best unilateral amputee sprinters. SUBJECTS: Five men, all unilateral lower-limb amputee (one transfemoral, four transtibial) athletes. The individual with transfemoral amputation used a Endolite Hi-activity prosthesis incorporating a CaTech hydraulic swing and stance control unit, a Flex-Foot Modular III, and an ischial containment total contact socket. Those with transtibial amputations used prostheses incorporating a Flex-Foot Modular III and patellar tendon-bearing socket, with silicone sheath liner (Iceross) and lanyard suspension. DESIGN: Case series. Subjects were videotaped sprinting through a performance area. Sagittal plane lower-limb kinematics derived from manual digitization (at 50 Hz) of the video were determined for three sprint trials of the prosthetic and sound limb. Hip, knee, and ankle kinematics of each subject's sound and prosthetic limb were compared to highlight kinematic alterations resulting from the use of individual prostheses. Comparisons were also made with mean data from five able-bodied men who had similar sprinting ability. RESULTS: Sound limb hip and knee kinematics in all subjects with amputation were comparable to those in able-bodied subjects. The prosthetic knee of the transfemoral amputee athlete fully extended early in swing and remained so through stance. In the transtibial amputee athletes, as in able-bodied subjects, a pattern of stance flexion-extension was evident for both limbs. During stance, prosthetic ankle angles of the transtibial amputee subjects were similar to those of the sound side and those of able-bodied subjects. CONCLUSION: Prosthetic limb kinematics in transtibial amputee subjects were similar to those for the sound limb, and individuals achieved an "up-on-the-toes" gait typical of able-bodied sprinting. Kinematics for the prosthetic limb of the transfemoral amputee subject were more typical of those seen for walking. This resulted in a sprinting gait with large kinematic asymmetries between contralateral limbs.     

A study of the external forces and moments at the shoulder and elbow while performing every day tasks

OBJECTIVES: To establish a database of upper limb kinematics and kinetics to support the development of a biomechanical model of the shoulder and elbow. DESIGN: Ten unimpaired subjects were studied when performing 10 different tasks of every day living. BACKGROUND: The development of biomechanical models of the upper limb to support the design of total joint replacements requires data on the commonly performed activities. Unlike the lower limb, this involves the selection of the tasks believed to be the most common. METHODS: Kinematic data were collected using four video cameras to track the movements of reflective markers attached to the upper limb and trunk. The rigid body kinematics was then analysed and the external forces and moments at the shoulder and elbow were calculated using inverse dynamics. RESULTS: The greatest ranges of motion at the shoulder occurred during reaching and lifting tasks as did the greatest shoulder moment (14.3 Nm flexion). The greatest elbow flexion occurred while reaching the back of the head but the greatest moment (5.8 Nm) occurred while lifting a block to head height. CONCLUSIONS: A database of ranges of motion and external forces and moments has been established to support the development of biomechanical models of the upper limb. RELEVANCE: The development of biomechanical models to support the design of upper limb joint replacements requires detailed knowledge of the types and magnitudes of forces and moments at the joints.     

Quantification of soft tissue artefact in motion analysis by combining 3D fluoroscopy and stereophotogrammetry: a study on two subjects

BACKGROUND: Soft tissue artefact is the most invalidating source of error in human motion analysis using optoelectronic stereophotogrammetry. It is caused by the erroneous assumption that markers attached to the skin surface are rigidly connected to the underlying bones. The quantification of this artefact in three dimensions and the knowledge of how it propagates to relevant joint angles is necessary for the interpretation of gait analysis data. METHODS: Two subjects, treated by total knee replacement, underwent data acquisition simultaneously with fluoroscopy and stereophotogrammetry during stair climbing, step up/down, sit-to-stand/stand-to-sit, and extension against gravity. The reference 3D kinematics of the femur and tibia was reconstructed from fluoroscopy-based tracking of the relevant prosthesis components. Soft tissue artefact was quantified as the motion of a grid of retro-reflecting makers attached to the thigh and shank with respect to the underlying bones, tracked by optoelectronic stereophotogrammetry. The propagation of soft tissue artefact to knee rotations was also calculated. FINDINGS: The standard deviation of skin marker trajectory in the corresponding prosthesis-embedded anatomical frame was found up to 31 mm for the thigh and up to 21 mm for the shank. The ab/adduction and internal/external rotation angles were the most affected by soft tissue artefact propagation, with root mean square errors up to 192% and 117% of the corresponding range, respectively. INTERPRETATIONS: In both the analysed subjects the proximal thigh showed the largest soft tissue artefact. This is subject- and task-specific. However, larger artefact does not necessarily produce larger propagated error on knee rotations. Propagated errors were extremely critical on ab/adduction and internal/external rotation. These large errors can nullify the usefulness of these variables in the clinical interpretation of gait analysis.     

Vacuum level effects on gait characteristics for unilateral transtibial amputees with elevated vacuum suspension

BackgroundThe elevated vacuum suspension system has demonstrated unique health benefits for amputees, but the effect of vacuum pressure values on gait characteristics is still unclear. The purpose of this study was to investigate the effects of elevated vacuum levels on temporal parameters, kinematics and kinetics for unilateral transtibial amputees.MethodsThree-dimensional gait analysis was conducted in 9 unilateral transtibial amputees walking at a controlled speed with five vacuum levels ranging from 0 to 20 in Hg, and also in 9 able-bodied subjects walking at self-preferred speed. Repeated ANOVA and Dunnett's t-test were performed to determine the effect of vacuum level and limb for within subject and between groups.FindingsThe effect of vacuum level significantly affected peak hip external rotation and external knee adduction moment. Maximum braking and propulsive ground reaction forces generally increased for the residual limb and decreased for the intact limb with increasing vacuum. Additionally, the intact limb experienced an increased loading due to gait asymmetry for several variables.InterpretationThere was no systematic vacuum level effect on gait. Higher vacuum levels, such as 15 and 20 in Hg, were more comfortable and provided some relief to the intact limb, but may also increase the risk of osteoarthritis of the residual limb due to the increased peak external hip and knee adduction moments. Very low vacuum should be avoided because of the negative effects on gait symmetry. A moderate vacuum level at 15 in Hg is suggested for unilateral transtibial amputees with elevated vacuum suspension.