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.     

Effects of diabetic peripheral neuropathy on gait in vascular trans-tibial amputees

BackgroundPatients with diabetes often develop diabetic peripheral neuropathy, which is a distal symmetric polyneuropathy, so foot function on the non-amputated side is expected to affect gait in vascular trans-tibial amputees. However, there is little information on the kinematics and kinetics of gait or the effects of diabetic peripheral neuropathy in vascular trans-tibial amputees. This study aimed to clarify these effects, including the biomechanics of the ankle on the non-amputated side.MethodsParticipants were 10 vascular trans-tibial amputees with diabetic peripheral neuropathy (group V) and 8 traumatic trans-tibial amputees (group T). Each subject's gait was analyzed at a self-selected speed using a three-dimensional motion analyzer and force plates.FindingsAnkle plantarflexion angle, heel elevation angle, and peak and impulse of anterior ground reaction force were smaller on the non-amputated side during pre-swing in group V than in group T. Center of gravity during pre-swing on the non-amputated side was lower in group V than in group T. Hip extension torque during loading response on the prosthetic side was greater in group V than in group T.InterpretationThese findings suggest that the biomechanical function of the ankle on the non-amputated side during pre-swing is poorer in vascular trans-tibial amputees with DPN than in traumatic trans-tibial amputees; the height of the center of gravity could not be maintained during this phase in vascular trans-tibial amputees with diabetic peripheral neuropathy. The hip joint on the prosthetic side compensated for this diminished function at the ankle during loading response.     

A comparison of two prosthetic feet on the multi-joint and multi-plane kinetic gait compensations in individuals with a unilateral trans-tibial amputation

OBJECTIVE: To determine the effects of two different prosthetic feet on the three-dimensional kinetic patterns of both the prosthetic and sound limbs during unilateral trans-tibial amputee gait. DESIGN: Eleven individuals with a unilateral trans-tibial amputation participated in two walking sessions: once while using the conventional SAFE foot, the other while using the dynamic Flex foot. BACKGROUND: Despite the wide variation in the design of prosthetic feet, the benefits of these prostheses remain unclear. METHODS: During each test session, peak joint moments and powers in the sagittal, transverse and frontal planes were examined, as subjects walked at a comfortable speed. RESULTS: The majority of the kinetic differences that occurred due to the changing of prosthetic foot type were limited to ankle joint variables in the sagittal plane with greater peak moments and power during propulsion for the Flex foot compared to the SAFE foot. However, effects were also found at joints proximal to the prosthesis (e.g. knee) and differences were also found in the kinetics of the sound limb. CONCLUSION: The dynamic Flex foot allowed subjects to rely more heavily on the prosthetic foot for propulsion and stability during walking with minimal compensations at the remaining joints. RELEVANCE: Determining the biomechanical differences between the conventional and dynamic prosthetic feet may advocate the use of one prosthetic foot type over another. This information, when used in conjunction with subjective preferences, may contribute to higher functioning and greater satisfaction for individuals with a lower limb amputation.     

Evolution in prostheses for sprinters with lower-limb amputation]

For about 15 years, technical advances in prosthetic treatment have been the main factor in the increased performance of athletes with lower-limb amputation. For trans-tibial amputation, the prosthesis for sprinting is composed of a gel liner and a socket joined by a locking or virtual vacuum liner. Because of these dynamic properties, the carbon prosthetic foot equipped with tacks ensures outstanding performance. For trans-femoral amputation, a hydraulic swing and a stance control unit are added to the same prosthesis. In comparison with the able-bodied runner, athletes with amputation have smaller loading times in the prosthetic limb and larger ones in the sound limb. The length of the energy-storing prosthetic foot is determined by the "up-on-the-toes" running gait. The sprinting gait with trans-tibial amputation is almost symmetrical. The hip extensor effort is the main compensation of propulsion reduction with lower-limb amputation. With trans-femoral amputation, the lack of knee increases the asymmetry. The total prosthetic knee extension (early in late-swing phase and lasting during total stance phase) compensates with extension of both hips, especially the opposite one. The amputation and sound limb load transfer with lumbar hyperlordosis concern the pelvis, trunk and shoulders. Because of athletes with amputation, research in prosthetic treatment has progressed. The development of orthotics and prostheses for such athletes has benefited non-athletes with amputation.     

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.     

Joint loading and bone mineral density in persons with unilateral, trans-tibial amputation

Background. Persons with unilateral, lower-extremity amputation sometimes develop osteoarthritis in the intact limb. The purpose of this study was to investigate gait mechanics and bone mineral density in unilateral, trans-tibial amputees to test the hypotheses that the intact limb knee and hip will have larger frontal plane net joint moments and bone mineral density than the prosthetic side and the limbs of control subjects.

Methods. Proximal tibia and femoral neck bone mineral density and gait mechanics were measured from nine subjects with a unilateral, trans-tibial amputation and from age, gender, and mass matched control subjects.

Findings. The amputee intact proximal tibia bone mineral density and peak knee internal abduction moment were 45% (P = 0.001) and 56% (P = 0.028) greater, respectively, than the prosthetic side. The intact limb femoral neck bone mineral density and peak hip internal abduction moment were 12% (P = 0.095) and 33% (P = 0.03) greater, respectively, than the prosthetic side. The intact knee frontal plane moment and bone mineral density were moderately larger than the control knee, while the intact and control hip were similar.

Interpretation. Elevated frontal plane net joint moments and bone mineral density suggest the potential exists for premature knee joint degradation. Measuring frontal plane joint mechanics and bone mineral density may be important tools for assessing joint health in persons with unilateral, trans-tibial amputation.     

股四头肌与腘绳肌在痉挛性偏瘫步态中拮抗收缩的动态肌电图研究

本文目的是提出拮抗收缩曲线（Ｃｏ－ＣｏｎｔｒａｃｔｉｏｎＰｒｏｆｉｌｅ，ＣＣＰ）的客观评价方法，并用来测量中风患者步行中作用于膝关节的主动肌和拮抗肌的拮抗收缩水平。应用表面肌电图记录９例正常人，６例痉挛性偏瘫患者的股四头肌和绳肌在步行中的肌电活动。结果显示，痉挛性偏瘫患者的ＣＣＰ水平除在负重期与正常人的ＣＣＰ达到同样的高峰水平外，在站立相的大部分时期及迈步相的后期均较正常人的ＣＣＰ水平显著增高（Ｐ＜０．０５）。这表明ＣＣＰ评定方法客观，具有能够揭示拮抗收缩模式变异原因的显著特点，可作为痉挛治疗前后评价的一种方法。     

Contribution of accelerated body masses to able-bodied gait

OBJECTIVE: The objectives of this study were to demonstrate that data from a video-based system could be used to estimate the net effect of the external forces during gait, to determine the contribution of the trunk and upper and lower limbs using their accelerated body masses, and to test the hypothesis that the thigh mainly assumed lower limb propulsion during able-bodied locomotion. METHODS: The gait of 16 able-bodied subjects was assessed using an eight-camera video-based system and two force plates. The right limb was the leading limb, and there were two trials per subject. Although data from all the body segments were used to answer the first two objectives, only right limb information was used to address the third objective. RESULTS: Pearson's coefficients of correlation and root mean square errors were calculated to determine the difference between the curves obtained from the sum of the external forces and that of the accelerated masses. These were >0.85, and the mean root mean square error was <4 N. Analyses of variance were performed on the peak forces developed by the trunk and the upper and lower limbs along each axis. Tukey's posthoc tests (P < 0.05) revealed that the trunk was the principal contributor of external forces in the frontal and transverse planes, whereas the lower limbs were found to be more important in the plane of progression. Analyses of variance and Tukey's posthoc tests (P < 0.05) were performed on the peak forces developed by each segment of the right limb. In decreasing order, the thigh, shank, and foot displayed the highest mass-acceleration products in the right limb during gait. CONCLUSIONS: A video-based system was able to determine the net effect of the external forces with the summation of the mass-acceleration products during able-bodied gait. The trunk and lower limbs were the dominant body segments responsible for the production of external forces during able-bodied gait, whereas the thighs contributed more to the ground reaction force than the foot and shank for forward progression in able-bodied gait.     

不同温度对缺血兔骨骼肌不可逆变性时限的影响

背景肢体离断一定时间后能否再植?目前尚无确切判定标准.目的根据骨骼肌线粒体变化确定缺血兔骨骼肌的不可逆变性时限,为临床断指再植提供判定标准.设计设立对照的实验研究.地点和对象在吉林大学白求恩医学部病生教研室完成.市售大白兔30只,雌雄不拘,平均体质量2.3 kg.干预将兔离断后肢30侧分为4℃,℃两组,分别置于4℃,℃恒温冰箱中.采用电镜的方法动态观察缺血兔骨骼肌的变性过程,判定肌肉的不可逆变性点.主要观察指标电镜观察4℃和6℃时不同时间点兔骨骼肌线粒体变化.结果4℃时缺血兔骨骼肌的不可逆变性时限为50 h;6℃时缺血兔骨骼肌的不可逆变性时限为28 h.结论离断肢体在4℃时超过50 h,℃时超过28 h即应谨慎再植.     

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.     

Walking characteristics of runners with a transfemoral or knee-disarticulation prosthesis

BackgroundRunning with prostheses has become a common activity for amputees participating in sports and recreation. However, very few studies have characterized the kinematic and kinetic parameters of walking in individuals with amputation who are runners. Thus, this study attempts to elucidate the kinematics and kinetics of walking in runners with a unilateral transfemoral amputation or knee-disarticulation.MethodsThis study experimentally compares the prosthetic and intact limbs of runners with prostheses as well as compares the findings against the limbs of age-matched able-bodied individuals while walking. Fourteen runners with a unilateral transfemoral amputation or knee-disarticulation were recruited and 14 age-matched able-bodied individuals were prepared using gait database. Spatiotemporal, kinematic, and kinetic parameters of walking were analyzed using a 3-demensional motion capture system.ResultsThe results showed that the peak ankle positive power at pre-swing and peak hip positive power from loading response to mid stance in the intact limb were significantly larger than that in the prosthetic limb. Moreover, to compensate for missing anatomical functions on the prosthetic limb, it appeared that the intact limb of the runners generated larger peak joint power by producing more ankle plantarflexor and hip extensor moments while walking.InterpretationThis study demonstrated that the runners rely on their intact limb while walking. Training of hip extensor muscles of the intact limb may be beneficial for these individuals.     

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.     

单侧小腿截肢患者穿假肢后的步态运动学参数研究

目的 采用计算机辅助康复环境(CAREN)步态评估系统分析单侧小腿截肢患者穿假肢后的步态运动学参数,并分析其产生差异的原因。 方法 选取单侧小腿中段截肢但均装配假肢的受试者9例设为假肢组,同期选择健全受试者11例设为标准组,通过CAREN步态评估系统对2组受试者的步态运动学参数进行收集、处理、分析,并根据分析报告阐明产生差异原因。 结果 假肢组步态时相性指数为(0.88±0.04),其假肢侧的步长、支撑期百分比、髋关节支撑期最大伸展角度、膝关节支撑期最大屈曲角度、踝关节足跟着地背屈角度、踝关节支撑期最大背屈角度、踝关节支撑期最大跖屈角度与健侧比较,差异均有统计学意义(P<0.05）。假肢组假肢侧的步行速度、步态周期、跨步长、支撑期百分比、髋关节足跟落地屈髋角度、髋关节支撑期最大伸展角度、髋关节支撑期最大屈曲角度、膝关节足跟着地屈膝角度、踝关节足跟着地背屈角度、踝关节支撑期最大跖屈角度、踝关节支撑期最大背屈角度与标准组双侧均值比较,差异均有统计学意义(P<0.05）。 结论 单侧小腿截肢者穿戴假肢后步态时相对称性为（0.88±0.04）,假肢侧踝关节运动学参数显著弱于自身健侧,其时空与运动学参数也显著弱于健全人。     

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.     

Loading rates in unilateral transfemoral amputees with running-specific prostheses across a range of speeds

BackgroundUnderstanding the potential risks of running-related injuries in unilateral transfemoral amputees contributes to the development and implementation of the injury prevention programme in running gait rehabilitation. We investigated the vertical ground reaction force loading in unilateral transfemoral amputees who used running-specific prostheses across a range of running speeds.MethodsTen unilateral transfemoral amputees and ten non-amputees performed running trials on an instrumented treadmill at the incremental speeds of 30, 40, 50, and 60% of their maximum acquired speeds. Per-step and cumulative vertical instantaneous loading rates were calculated from the vertical ground reaction force in the affected, unaffected, and non-amputated control limbs.FindingsBoth the per-step and cumulative vertical instantaneous loading rates of the unaffected limbs in runners with unilateral transfemoral amputation were significantly greater than the affected and non-amputated control limbs at all speeds.InterpretationThe results of the present study suggest that runners with unilateral transfemoral amputation may be exposed to a greater risk of running-related injuries in their unaffected limbs compared to the affected and non-amputated control limbs.     

The influence of gait speed on co-activation in unilateral spastic cerebral palsy children

Background

Physiological co-activation of antagonistic muscles during gait allows stability of loaded joints. Excessive co-activation restrains motion and increases energy expenditure. Co-activation is increased by gait speed and in the case of upper motor neuron lesions. This study aimed to assess the pathological component of co-activation in children with unilateral cerebral palsy.

Methods

10 children with unilateral cerebral palsy and 10 typically developing children walked at spontaneous, slow and fast speeds. The spatio-temporal parameters and electromyographic activity of the rectus femoris, vastus medialis, semi-tendinosus, tibialis anterior and soleus of both lower limbs were recorded. A co-activation index was computed from the EMG envelopes. A mixed linear model was used to assess the effect of walking speed on the index of the antagonistic muscle couples (rectus femoris/semi-tendinosus, vastus medialis/semi-tendinosus and tibialis anterior/soleus) in the different limbs.

Findings

A greater effect of walking speed on co-activation was found in the involved limbs of children with cerebral palsy for all muscle couples, compared with their uninvolved limbs and the limbs of typically developing children. In typically developing children, but not in children with cerebral palsy, the effect of gait speed on the co-activation index was lower in the rectus femoris/semi-tendinosus than in the other agonist/antagonist muscle couples.

Interpretations

In children with cerebral palsy, a pathological component of muscle activation might be responsible for the greater increase in co-activation with gait speed in the involved limb. Altered motor control could explain why the co-activation in the rectus femoris/semi-tendinosus couple becomes more sensitive to speed.     

Muscle power compensatory mechanisms in below-knee amputee gait

OBJECTIVE: This three-dimensional and bilateral gait study on five below-knee amputees was undertaken to demonstrate the following: (1) how hip muscle powers can compensate for the lack of ankle function on the amputated side; and (2) how these compensatory mechanisms can influence muscle power activities in the sound limb. DESIGN: Gait data were assessed by an eight-camera high-speed video system synchronized to two force plates. The three-dimensional mechanical muscle powers were calculated at the joints of the lower limbs. Significant differences between each limb were determined using the Student's t test for paired data with P < 0.05. RESULTS: In the absence of ankle plantar flexor power, hip extensors and flexors as well as hip external rotators became the major power generators, whereas hip abductors and adductors and knee extensors muscle powers became the main source of absorption. For the sound limb, increased hip extensor activity was observed, accompanied by less hip abduction-adduction activity. CONCLUSIONS: Perturbations in below-knee amputee gait affected the hip muscle powers on the amputated side in all three planes, although the hip frontal plane balance was modified in the sound limb.     

Electromyographic patterns accompanying isokinetic exercise under varying speed and sequencing conditions

The purposes of this study were: a) to investigate electromyographic patterns accompanying isokinetic exercise under varying speed and sequencing conditions, and b) to investigate the role of antagonist coactivation under these same conditions. Five adult males performed maximal knee extensions and flexions on a modified Orthotron isokinetic dynamometer. Tests were done at four speeds (100-400 degrees/sec) and under two counterbalanced conditions: extension followed by flexion (E/F) and flexion followed by extension (F/E). Simultaneous recordings of torque, knee joint position and agonist/antagonist EMG changes from the quadriceps and hamstring musculature were collected and analyzed. No consistent EMG patterns emerged that inferred intermittent surges of muscular activity as the primary mechanism yielding double peaked torques that characteristically occur in isokinetic exercise. Further analyses revealed relatively small co-contractions of antagonists during the various phases of movement. The findings suggest that gravity and inertia of the limb/lever system were the major factors responsible for limb deceleration and substantive antagonist co-contraction was not required for braking. If isokinetic knee flexion and extension exercises are used for conditioning or developmental purposes of healthy subjects, any distraction of the co-contracting antagonist from the recorded force of the agonist appears to be small once the activity is learned.     

Biomechanical compensations of the trunk and lower extremities during stepping tasks after unilateral transtibial amputation

BackgroundLower extremity movement compensations following transtibial amputation are well-documented and are likely influenced by trunk posture and movement. However, the biomechanical compensations of the trunk and lower extremities, especially during high-demand tasks such as step ascent and descent, remain unclear.MethodsKinematic and kinetic data were collected during step ascent and descent tasks for three groups of individuals: diabetic/transtibial amputation, diabetic, and healthy. An ANCOVA was used to compare peak trunk, hip and knee joint angles and moments in the sagittal and frontal planes between groups. Paired t-tests were used to compare peak joint angles and moments between amputated and intact limbs of the diabetic/transtibial amputation group.FindingsDuring step ascent and descent, the transtibial amputation group exhibited greater trunk forward flexion and lateral flexion compared to the other two groups (P < 0.016), which resulted in greater low back moments and asymmetric loading patterns in the lower extremity joints. The diabetic group exhibited similar knee joint loading patterns compared to the amputation group (P < 0.016), during step descent.InterpretationThis study highlights the biomechanical compensations of the trunk and lower extremities in individuals with dysvascular transtibial amputation, by identifying low back, hip, and knee joint moment patterns unique to transtibial amputation during stepping tasks. In addition, the results suggest that some movement compensations may be confounded by the presence of diabetes and precede limb amputation. The increased and asymmetrical loading patterns identified may predispose individuals with transtibial amputation to the development of secondary pain conditions, such as low back pain or osteoarthritis.     

Effects of changes in cadence, prosthetic componentry, and time on interface pressures and shear stresses of three trans-tibial amputees

OBJECTIVE: To evaluate the effects of changes in cadence, prosthetic componentry, and time on interface pressures and resultant shear stresses in trans-tibial amputee case studies. DESIGN: Interface stresses were monitored using custom-designed instrumentation at 13 sites on three subjects with unilateral trans-tibial amputation walking with patellar-tendon-bearing prosthetic limbs. BACKGROUND: Previous studies suggested that week-to-week residual limb changes altered interface stresses more than did alterations in prosthetic alignment. No studies investigating effects of changes in cadence or componentry on interface stress distributions nor comparing their influence with week-to-week changes have been conducted previously. METHODS: Five different prosthetic componentry configurations were tested at each of three cadences in four sessions. Data were analysed for the magnitudes and timings of peak pressures and resultant shear stresses as well as corresponding resultant shear angles. RESULTS: None of the three cadences or five componentry configurations consistently induced significantly (P<0.05) higher or lower interface stress magnitudes for all subjects. However, an Aluminium Pylon/SACH Foot combination compared with an AirStance (pneumatic shank)/Seattle LightFoot unit induced later peak interface stress timings as a percentage of stance phase. Higher and more frequent interface stress changes were seen between the weekly sessions than between different cadences or between different componentry configurations. CONCLUSION: The amputees' capabilities to compensate for week-to-week residual limb changes were less than those for intra-session cadence or componentry alterations. RELEVANCE: Results suggest that effective techniques to accommodate week-to-week residual limb fluctuations could have a greater impact on maintaining consistent interface stress distributions than do adjustments in cadence or componentry.