Intra-individual biomechanical effects of a non-microprocessor-controlled stance-yielding prosthetic knee during ramp descent in persons with unilateral transfemoral amputation.

BACKGROUND:: A stance-yielding mechanism for prosthetic knees may reduce lower limb loading during specific activities, but quantitative data are insufficient. OBJECTIVES:: To clarify the biomechanical effect of a non-microprocessor-controlled stance-yielding mechanism on ramp descent for individuals with unilateral transfemoral amputation. STUDY DESIGN:: Intra-subject intervention study. METHODS:: Seven individuals with unilateral transfemoral amputation underwent three-dimensional motion analysis of ramp descent with and without activating a stance-yielding mechanism. Regarding early-stance internal joint moment and ground reaction force, whole-group and subgroup analyses stratified by stance prosthetic knee flexion were performed to verify differences in prosthetic side and contralateral limb loading between conditions. RESULTS:: Whole-group analysis revealed significant reduction in early-stance prosthetic knee extension moment with stance-yielding mechanism activation. Changes in prosthetic side hip extension moment and contralateral limb loading were inconsistent between conditions. Subjects with prosthetic stance knee flexion walked slower with a smaller stride and greater increase in aft ground reaction force and ankle dorsiflexion moment when stance-yielding was activated. CONCLUSION:: Stance-yielding mechanism has a biomechanical potential to decrease excessive knee hyperextension. However, prosthetic side stance knee flexion induced by the stance-yielding mechanism might not necessarily reduce the mechanical load on residual hip or contralateral lower limb joints. CLINICAL RELEVANCE: This study showed individual variability in the possibility of reducing the load on the remaining lower limb when using a non-microprocessor-controlled stance-yielding knee. This suggests that individualized prosthetic management and monitoring the activities of individuals wearing a stance-yielding prosthetic knee are crucial to maximize the benefits of stance-yielding prosthetic knees.

Kinetic differences between level walking and ramp descent in individuals with unilateral transfemoral amputation using a prosthetic knee without a stance control mechanism.

BACKGROUND: Individuals with transfemoral amputation (TFA) have difficulty in descending ramps. Although individuals with TFA who descend ramps are speculated to have greater biomechanical demands, this has not been quantified. RESEARCH QUESTION: How do individuals with TFA wearing a prosthetic knee without a stance control mechanism adapt their gait biomechanics to a slightly declined surface? METHODS: We retrospectively analyzed data of level walking and ramp descent (5° decline) from six subjects with TFA who used a prosthesis without a stance control mechanism. Ground reaction force and joint moment, power, and kinematics were derived from three-dimensional motion capture, combined with force measurement. Kinematic and kinetic variables were compared during level walking and ramp descent using the paired tests. RESULTS: Compared with level walking, ramp descent increased the maximum contralateral vertical ground reaction force by 16% of the body weight, on average (standard deviation: 20%). Ramp descent tended to induce smaller concentric hip power during late swing and greater hip eccentric power on the prosthetic-side during late stance. Greater biomechanical demands during ramp descent were indicated by increased maximum medial ground reaction force on both sides, and eccentric joint power of the contralateral ankle during stance. SIGNIFICANCE: For individuals with TFA using a prosthetic knee without a stance control mechanism, descending a ramp can increase loading on the contralateral limb during the loading response; slower walking may alleviate the effect. Ramp descent can change prosthetic-side hip muscles' control of the swinging prosthetic limb, eccentric work on the contralateral ankle plantarflexors during stance, and mediolateral balance. All of these factors should be taken into consideration when individuals with TFA learn to descend a ramp.

Foot clearance strategy for step-over-step stair climbing in transfemoral amputees.

BACKGROUND AND AIM: Stair ascent is a particularly challenging task for transfemoral amputees. The aim of this clinical note was to describe the kinematic features of foot clearance in transfemoral amputee who can ascend stairs using a step-over-step strategy. TECHNIQUE: The marker trajectories of the first metatarsophalangeal joint (Mt1) and clearance height were measured in two transfemoral amputees who could (TF1) and could not (TF2) climb stairs using a step-over-step strategy. DISCUSSION: The Mt1 marker trajectories of the TF1 moved backward in the early swing phase, and the trajectory followed an off-centered parabolic arc to achieve a similar clearance height as able-bodied subjects. TF2 could not climb the stairs without tripping in each step. An effective compensatory strategy to avoid tripping during stair climbing may be to use the hip joint for a backward extension and rapid flexion of the prosthetic leg during the early swing phase. CLINICAL RELEVANCE: The foot clearance strategy in transfemoral amputees who can climb stairs using a step-over-step strategy will help us better understand adaptive prosthetic control and thus develop more effective gait rehabilitation programs.

Limb fitting for quadruple amputees: report of two cases of symmetrical peripheral gangrene caused by pneumococcal purpura fulminans.

BACKGROUND: We report our experiences of prosthetic fitting in quadruple amputees. Two patients underwent quadruple amputation after suffering from disseminated intravascular coagulation in conjunction with pneumococcemia with purpura fulminans. CASE DESCRIPTION AND METHODS: The first patient, a 52-year-old man, underwent bilateral transradial, left transtibial, and right transfemoral amputation, and the second patient, a 62-year-old man, underwent bilateral transradial and bilateral transfemoral amputation, both for symmetrical peripheral gangrene subsequent to septic shock. FINDINGS AND OUTCOMES: The amputations were accompanied by skin damage due to ischemic tissue changes both on the stumps and on the nose and/or lips. The combination of the intensive prosthetic rehabilitation program and supportive medical care led to completely independent functioning, including driving a car, with the use of four prosthetic limbs and a wheelchair in both cases. CONCLUSION: Early initiation of a multidisciplinary approach can properly address impairments and minimize future disability.

Factors affecting stair-ascent patterns in unilateral transfemoral amputees.

BACKGROUND: Patterns and ease of stair ambulation influence amputees' level of satisfaction with their rehabilitation, confidence level, and motivation for continued rehabilitation, demonstrating the importance of stair-ascent data for rehabilitation. However, little is known about the determinants of stair-ascent patterns in unilateral transfemoral amputees. OBJECTIVES: To investigate the factors affecting stair-ascent patterns in transfemoral amputees. STUDY DESIGN: Cross-sectional survey. METHODS: Stair-ascent patterns were evaluated using the Stair Assessment Index. We collected Stair Assessment Index data as well as demographic and clinical data (sex, age, height, mass, amputation side, reason for amputation, time since amputation, and residual limb length) from 25 transfemoral amputees. RESULTS: Statistical analyses revealed that age was negatively correlated and time since amputation was positively correlated with Stair Assessment Index. In contrast, height, body mass, and residual limb lengths were not correlated with Stair Assessment Index. CONCLUSION: The results of this study suggest that in unilateral transfemoral amputee, (1) both age and time since amputation could affect stair-climbing patterns and (2) residual limb length should not be a limiting factor for stair climbing if the transfemoral amputee has a certain minimum residual limb length. CLINICAL RELEVANCE: Rehabilitation teams should carefully consider nonmodifiable predisposing factors such as age and time since amputation. However, they may be able to carry on stair-ascent rehabilitation for transfemoral amputees disregarding residual limb length (depending on the length).

Lower extremity joint kinematics of stair ascent in transfemoral amputees.

BACKGROUND: Stair ascent is a very demanding task for transfemoral amputees (TFAs). The purpose of this study was to investigate the lower extremity joint kinematics of TFAs who can climb stairs using a step-over-step gait pattern without an active artificial prosthetic knee joint or handrail use. CASE DESCRIPTION AND METHODS: Case series. Participants were two traumatic TFAs and 10 control participants. Both TFAs used a single-axis prosthetic knee joint in daily living. Sagittal plane joint kinematics were recorded at 60 Hz using an eight-camera motion analysis system and digital video camera. FINDINGS AND OUTCOMES: From the instant of touchdown, the prosthetic knee joint was rapidly extended and remained fully extended until toe-off. In the latter half of the stance phase, the knee and ankle joints of the sound limb simultaneously showed rapid joint flexion during continuous extension. Further, the ankle joint of the sound limb showed greater plantarflexion at the end of the stance phase. CONCLUSION: These results suggest that the TFA in the present study would (1) extend the prosthetic knee joint to prevent the knee flexion generated by the bodyweight (plus ground reaction force and/or joint moment), and (2) lift the whole body in an upward direction using strong counter-movements and greater joint extension during the stance phase.

Changes of joint moments in the gait of normal subjects wearing laterally wedged insoles.

OBJECTIVE: The purpose of this study was to assess the kinematic and kinetic effects of wearing a laterally wedged insole on the knee joint moment during gait, specifically in the frontal plane, in normal healthy adults. DESIGN: Motion analyses were conducted with (1) a three-dimensional motion analysis system and (2) ground reaction force analysis using force platforms when subjects walked under three different insole conditions: no wedge, a low wedge with a 3-degree lateral angle, and a high wedge with a 6-degree lateral angle. RESULTS: The high-wedge insole significantly reduced the knee joint varus moment during gait compared with the gait with the no-wedge insole. The actual segment angles at the subtalar and knee joints did not show any changes due to insole conditions. In contrast, the subtalar joint valgus moment increased for the high-wedge insole. This finding was correlated with a greater moment arm of the subtalar joint valgus moment with the high-wedge insole. CONCLUSIONS: These results indicate that, under dynamic conditions, the subjects wearing laterally wedged insoles had both changes of moments at the subtalar and knee joints via the more laterally shifted location of the center of pressure.