The gait initiation process in unilateral lower-limb amputees when stepping up and stepping down to a new level

BACKGROUND: Unilateral lower-limb amputees lead with their intact limb when stepping up and with their prosthesis when stepping down; the gait initiation process for the different stepping directions has not previously been investigated. METHODS: Ten unilateral amputees (5 transfemoral and 5 transtibial) and 8 able-bodied controls performed single steps up and single steps down to a new level (73 and 219 mm). Duration, a-p and m-l centre of mass and centre of pressure peak displacements and centre of mass peak velocity of the anticipatory postural adjustment and step execution phase were evaluated for each stepping direction by analysing data collected using a Vicon 3D motion analysis system. FINDINGS: There were significant differences (in the phase duration, peak a-p and m-l centre of pressure displacement and peak a-p and m-l centre of mass velocity at heel-off and at foot-contact) between both amputee sub-groups and controls (P<0.05), but not between amputee sub-groups. These group differences were mainly a result of amputees adopting a different gait initiation strategy for each stepping direction. INTERPRETATION: Findings indicate the gait initiation process utilised by lower-limb amputees was dependent on the direction of stepping and more particularly by which limb the amputee led with; this suggests that the balance and postural control of gait initiation is not governed by a fixed motor program, and thus that becoming an amputee will require time and training to develop alternative neuromuscular control and coordination strategies. These findings should be considered when developing training/rehabilitation programs.     

Gait analysis in amputees

There are marked differences from normal in both AK and BK gait. Forward velocity of walking is significantly lower in the amputee and is lower in the AK than in the BK subjects. Traumatic AK amputees ambulate with time-distance parameters of velocity, cadence, stride length and gait cycle which are all two standard deviations below normal. The same parameters for the traumatic BK amputee are only one standard deviation below normal. The symmetry of walking seen in the normal subject is not present in the lower extremity amputee. Measurements of single limb support times and motion analysis of the lower extremities as well as of the head, arms and trunk bear this out. This asymmetry of motion increases the excursion of the center of mass during each cycle and thereby increases the energy cost of ambulation. Energy cost of amputee gait often places the dysvascular AK amputee at his limits and strains other amputees severely. Further research is necessary to enable amputees to approach the walking capabilities of normal people.     

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.     

Gait patterns of transtibial amputee patients walking indoors barefoot

OBJECTIVE: To evaluate the gait patterns of lower limb amputee patients walking with and without shoes and to identify differences in barefoot gait patterns when using different prosthetic feet. DESIGN: Optoelectronic three-dimensional motion analysis of gait was performed on six transtibial amputees using a solid ankle cushion heel foot and a single-axis foot, both with and without shoes. RESULTS: Gait abnormalities were observed during barefoot walking when the solid ankle cushion heel foot was used. These included knee joint hyperextension of 9.9 +/- 2.0 degrees and the loss of ankle plantar flexion in the early stance phase. When the single-axis foot was used, knee flexion thrust declined from 9.9 +/- 3.7 degrees to 7.2 +/- 3.8 degrees and ankle plantar flexion decreased from 9.9 +/- 2.8 degrees to 7.0 +/- 2.1 degrees during the early stance phase. CONCLUSIONS: In transtibial amputees, significant gait abnormalities were observed during barefoot walking using the solid ankle cushion heel foot. These gait patterns improved, however, with use of a single-axis prosthetic foot, which permits a further plantar flexion after the initial contact.     

Chronic low back pain in traumatic lower limb amputees

OBJECTIVE: To ascertain the prevalence of back pain amongst traumatic lower limb amputees attending a regional rehabilitation centre and to determine the possible causes of back pain. DESIGN: All traumatic lower limb amputees given a semi-structured questionnaire to complete and a comparative subgroup of amputees with back pain and without back pain underwent physical examination, gait analysis, magnetic resonance scanning (MRI) and gait/standing stability analysis. SETTING: A subregional amputee rehabilitation centre. RESULTS: Transfemoral amputees were more likely to suffer from back pain (81 %) than transtibial amputees (62%) (p<0.05) and of those suffering from severe back pain, 89% and 81% also suffered from severe pain in the phantom limb and severe stump pain respectively. In two comparative subgroups of amputees there was no significant difference between back pain and pain-free groups except those with pain were more likely to have a body mass index (BMI) ratio above 50% of the recommended ratio. No difference in degeneration or disc disease between the groups on MR scans was found. Impact ground reaction forces during walking, irrespective of limb, were significantly greater (p < 0.05) in the pain-free group than in the pain group, as was walking speed. Gait asymmetry measures were similar in both groups. Centre of pressure displacement measures during standing were greater in the pain group than in the pain-free group. CONCLUSIONS: Low back pain in amputees is a significant problem equal to that of pain in the phantom limb and a biomechanical (myofascial) rather than a degenerative aetiology is suggested.     

Biomechanical adaptations of transtibial amputee sprinting in athletes using dedicated prostheses

OBJECTIVE: To determine the biomechanical adaptations of the prosthetic and sound limbs in two of the world's best transtibial amputee athletes whilst sprinting. DESIGN: Case study design, repeated measures. BACKGROUND: Using dedicated sprint prostheses transtibial amputees have run the 100 m in a little over 11 s. Lower-limb biomechanics when using such prostheses have not previously been investigated. METHODS: Moments, muscle powers and the mechanical work done at the joints of the prosthetic and sound limbs were calculated as subjects performed repeated maximal sprint trials using a Sprint Flex or Cheetah prosthesis. RESULTS: An increased hip extension moment on the prosthetic limb, with an accompanying increase in the amount of concentric work done, was the most notable adaptation in Subject 1 using either prosthesis. In Subject 2, an increased extension moment at the residual knee, and an accompanying increase in the amount of total work done, was the most notable adaptation using either prosthesis. This later adaptation was also evident in Subject 1 when using his Sprint Flex prosthesis. CONCLUSIONS: Increased hip work on the prosthetic limb has previously been shown to be the major compensatory mechanism that allow transtibial amputees to run. The increased work found at the residual knee, suggests that the two amputee sprinters used an additional compensatory mechanism. RELEVANCE: These findings provide an insight into the biomechanical adaptations that allow a transtibial amputee to attain the speeds achieved when sprinting.     

Longitudinal changes in transtibial amputee gait characteristics when negotiating a change in surface height during continuous gait

Background

Negotiating a raised surface during continuous gait is an important activity of daily living and is a potentially hazardous task with regards to trips, falls and fall-related injury. However, it is not known how recent transtibial amputees adapt to performing stepping gait tasks in the 6-month period following discharge from rehabilitation.

Methods

Recent transtibial amputees performed continuous gait trials, stepping onto and from a raised surface walkway representing the height of a street kerb, whilst kinematic and kinetic data were recorded at one, three and six months post-discharge from rehabilitation.

Findings

Walking speed increased when stepping down (p = 0.04) and was invariant across the study period when stepping up. At one month post-discharge, participants displayed an affected lead limb preference (90.8%) when stepping down and an intact lead limb preference (70.0%) when stepping up, although these lead limb preferences diminished over time. Participants spent more time in stance on the intact limb compared to the affected limb in both stepping down (trail limb) (p = 0.01) and stepping up (lead and trail limbs) (p = 0.05). Participants displayed significantly greater joint mobility and power bursts in the intact trail limb when stepping down and in the intact lead limb when stepping up.

Interpretation

Transtibial amputees prefer to exploit intact limb function to a greater extent, although over time, the means by which this occurs changes which affects the initial lead limb preferences. The results from the current study enable future evidence-based therapeutic and prosthetic interventions to be designed that improve transtibial amputee stepping gait.     

Postural Responses to Dynamic Perturbations in Amputee Fallers Versus Nonfallers: A Comparative Study With Able-Bodied Subjects

Vanicek N, Strike S, McNaughton L, Polman R. Postural responses to dynamic perturbations in amputee fallers versus nonfallers: a comparative study with able-bodied subjects.

Objectives

To quantify postural responses in amputee fallers versus nonfallers by using computerized dynamic posturography.

Design

All participants completed standard protocols on the Sensory Organization Test (SOT) and Motor Control Test (MCT) of the NeuroCom Equitest.

Setting

Human performance laboratory in a university in the United Kingdom.

Participants

Transtibial amputees (n=9) and able-bodied subjects (n=9) (all categorized into fallers and nonfallers according to their falls history in the previous 9mo).

Interventions

Not applicable.

Main Outcome Measures

Equilibrium and strategy scores on the SOT. Postural response latency and weight distribution on the MCT.

Results

Equilibrium scores were highest when somatosensory information was accurate, but there were no differences between the groups. Strategy scores were lower when visual cues and somatosensory information were inaccurate, and the fallers and nonfallers used a combination of ankle and hip strategies to prevent a loss of balance. The amputee nonfallers indicated they had a greater reliance on visual input even when it was inaccurate compared with the amputee fallers, whereas the control fallers used the hip strategy significantly more compared with the control nonfallers (SOT condition 6: 56±22 vs 72±10, P=.01). Weight distribution symmetry showed that the amputee nonfallers bore significantly more weight through their intact limb compared with the amputee fallers during backward and forward translations (P<.05).

Conclusions

The SOT and MCT appeared to be population specific and therefore did not reliably identify fallers among transtibial amputees or distinguish between community-dwelling control fallers and nonfallers. Amputee and control fallers can prevent a fall during challenging static and dynamic conditions by adapting their neuromuscular responses. The results from this study have important implications for amputee gait rehabilitation, falls prevention, and treatment programs.     

Evaluation of amputees]

INTRODUCTION: Review of the literature about evaluation of amputees. MATERIALS AND METHODS: A search of the Medline and Reedoc databases with the key words lower limb amputee, upper limb amputee, evaluation of lower limb amputee, evaluation of upper limb amputee, survey of lower limb amputee, survey of upper limb and the same words in French for reports on the evaluation of amputees. RESULTS: Evaluations of amputees differ according to the level of amputation (lower or upper limb) and age (adult or child). They concern standing balance, walking (lower limb) and the mono- or bimanual prehensile capacities with or without prostheses in daily living activities and leisure (upper limb) as well as quality of life, personal satisfaction, psychological impact and, in particular, coping strategies. DISCUSSION: For lower-limb amputees, tools to evaluate include scales of deambulation, of which few are valid in French, and global scales (on locomotor capacities, quality of life and satisfaction), which have been recently validated, but only one of them is valid in French. For upper-limb amputees, specific and valid tools are not available for adults; however, for children some functional capacity scales in daily activities have been validated and take into account psychomotor development. None of these tools are valid in French, and their use is scattered and limited to validation studies. CONCLUSION: Only a few tools to evaluate amputees are valid in French for adults, and they concern lower-limb amputees only. Validating some of these tools in French is necessary.     

The prevalence of knee pain and symptomatic knee osteoarthritis among veteran traumatic amputees and nonamputees

OBJECTIVE: To determine whether amputees have an increased risk of knee pain or symptomatic osteoarthritis (OA) compared with nonamputees. DESIGN: Retrospective cohort study. SETTING: Veterans Administration Patient Treatment and Outpatient Care files. PARTICIPANTS: All male unilateral (transtibial or transfemoral) traumatic amputee patients and a random sample of male nonamputees. Patients were excluded if they were younger than 40 years, had sustained a significant injury to their knee(s), or had a rheumatic disease. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The prevalence of knee pain and symptomatic knee OA. RESULTS: The age and average weight-adjusted prevalence ratio of knee pain among transtibial amputees, compared with nonamputees, was 1.3 (95% confidence interval [CI], 0.7-2.1) for the knee of the intact limb and 0.2 (95% CI, .05-0.7) for the knee of the amputated limb. The standardized prevalence ratio of knee pain in the intact limb and symptomatic OA among transfemoral amputees, compared with nonamputees, was 3.3 (95% CI, 1.5-6.3) and 1.3 (95% CI, 0.2-4.8), respectively. CONCLUSIONS: Stresses on the contralateral knee of amputees may contribute to secondary disability. Possible explanations include gait abnormalities, increased physiologic loads on the knee of the intact limb, and the hopping and stumbling behavior common in many younger amputees.     

The mechanics of landing when stepping down in unilateral lower-limb amputees

BACKGROUND: The ability to successfully negotiate stairs and steps is an important factor for functional independence. While work has been undertaken to understand the biomechanics of gait in lower-limb amputees, little is known about how amputees negotiate stairs and steps. This study aimed to determine the mechanics of landing in unilateral lower-limb amputees when stepping down to a new level. A secondary aim was to assess the effects of using a shank-mounted shock-absorbing device (Tele-Torsion Pylon) on the mechanics of landing. METHODS: Ten unilateral amputees (five transfemoral and five transtibial) and eight able-bodied controls performed single steps down to a new level (73 and 219 mm). Trials were repeated in amputees with the Tele-Torsion Pylon active and inactive. The mechanics of landing were evaluated by analysing peak limb longitudinal force, maximal limb shortening, lower extremity stiffness, and knee joint angular displacement during the initial contact period, and limb and ankle angle at the instant of ground-contact. Data were collected using a Vicon 3D motion analysis system and two force platforms. FINDINGS: Amputees landed on a straightened and near vertical limb. This limb position was maintained in transfemoral amputees, whereas in transtibial amputees knee flexion occurred. As a result lower extremity stiffness was significantly greater in transfemoral amputees compared to transtibial amputees and able-bodied controls (P<0.001). The Tele-Torsion Pylon had little effect on the mechanics of landing in transtibial amputees, but brought about a reduction in lower extremity stiffness in transfemoral amputees (P<0.05). INTERPRETATION: Amputees used a stepping strategy that ensured the direction of the ground reaction force vector was kept anterior of the knee joint centre. Using a Tele-Torsion Pylon may improve the mechanics of landing during downward stepping in transfemoral amputees.     

Standing posture and balance modalities in unilateral transfemoral and transtibial amputees

IntroductionLower limb amputation impairs postural performance that could be characterized by biomechanical parameters. This study is to investigate postural performance of persons with transfemoral and transtibial amputation compared to controls without amputation.MethodsEight transtibial, nine transfemoral and twelve able-bodied males participated in this study. Lower limb joints, pelvis and trunk angles were obtained from an optoelectronic motion analysis system to evaluate body posture parameters. The mean, range and speed of the center of pressure (CoP) in both antero-posterior and medio-lateral axes as well as the ellipse area covered by 90% of CoP and free moment were calculated using a single force-plate.Results and discussionDifferences in body posture were only noted between the non-amputee and the transtibial groups. Transtibial amputees leaned more forwardly their trunk by 3.5° compared to able-bodied (p = 0.028). The mean CoP position in transfemoral amputees was closer to the non-amputated side than transtibial amputees (p = 0.034) and as compared to the dominant side in non-amputees (p = 0.042). Factor analysis revealed three postural performance modalities. Non-amputees postural performance was characterized solely by body posture parameters. Transfemoral amputees exclusively favored a modality associated with standing balance parameters, whereas transtibial amputees exhibited a mixed modality comprising a combination of postural and balance parameters.ConclusionThese findings support that the level of amputation is characterized by postural performance modalities different from non-amputees. Clinicians could apply this knowledge as part of their routine rehabilitation program to enhance postural and standing balance assessments in unilateral transfemoral and transtibial amputees.     

Prosthetic intervention effects on activity of lower-extremity amputees

OBJECTIVE: To investigate the effect of prosthetic interventions on the functional mobility of lower-extremity amputees. DESIGN: Crossover with repeated measures. SETTING: Household and community environment. PARTICIPANTS: Twelve transtibial and 5 transfemoral amputees. INTERVENTIONS: For transtibial amputees, shock-absorbing versus rigid pylons. For transfemoral amputees, C-Leg versus Mauch SNS knees. MAIN OUTCOME MEASURES: Daily activity level (step count) and duration (minutes of activity). RESULTS: Pylon type had no effect on the daily activity level or duration of transtibial amputees. Knee type had no effect on the daily activity level or duration of transfemoral amputees. Transtibial amputees were more active on weekdays (3079+/-1515 steps/d) than weekends (2386+/-1225 steps/d) (P=.007). In general, lower-extremity amputees perform numerous short-duration bouts of activity (1-2 min) consisting of fewer than 17 steps/min, but activities of more than 15 minutes in duration were relatively rare (<1 per day). CONCLUSIONS: Intervention had no effect on amputee activity level and duration. Higher weekday activity levels of transtibial amputees suggest their vocational activities are more demanding than recreational activities. The fitting, alignment, and design of prosthetic components should be optimized for 1 to 2 minute bouts of activity consisting of only a few dozen steps.     

Individual responses to alignment perturbations in socket reaction moments while walking in transtibial prostheses

Background

The alignment of transtibial prostheses has a systematic effect on the mean socket reaction moments in amputees. However, understanding their individual differences in response to alignment perturbations is also important for prosthetists to fully utilize the socket reaction moments for dynamic alignment in each unique patient. The aim of this study was to investigate individual responses to alignment perturbations in transtibial prostheses with solid-ankle-cushion-heel feet.

Methods

A custom instrumented prosthesis alignment component was used to measure the socket reaction moments while walking in 11 amputees with transtibial prostheses under 17 alignment conditions, including 3° and 6° of flexion, extension, abduction, and adduction of the socket, 5 mm and 10 mm of anterior, posterior, lateral, and medial translation of the socket, and an initial baseline alignment. Coronal moments at 30% of stance and maximum sagittal moments were extracted for comparisons from each amputee.

Findings

In the coronal plane, varus moment at 30% of stance was generally reduced by adduction or medial translation of the socket in all the amputees. In the sagittal plane, extension moment was generally increased by posterior translation or flexion of the socket; however, this was not necessarily the case for all the amputees.

Interpretations

Individual responses to alignment perturbations are not always consistent, and prosthetists would need to be aware of this variance when addressing individual socket reaction moments during dynamic alignment in clinical setting.     

Does Unilateral Lower Limb Amputation Influence Ankle Joint Torque in the Intact Leg?

ObjectiveTo investigate ankle torque and steadiness in the intact leg of transtibial and transfemoral unilateral amputees.DesignComparative study.SettingMedical rehabilitation centers.ParticipantsFifteen persons with a unilateral transfemoral amputation, 8 persons with a transtibial amputation, and 14 able-bodied male participants volunteered to participate in this study (N=37).InterventionsNot applicable.Main Outcomes MeasuresMaximal isometric torque performed during ankle plantarflexion and dorsiflexion in the intact limb of amputees and in the dominant limb of able-bodied persons. The coefficient of variation (CV) of the plantarflexion torque was calculated over 5 seconds during a submaximal isometric contraction (15%) in order to assess torque steadiness. Furthermore, electromyographic activity (the root mean square amplitude) of the gastrocnemius medialis and tibialis anterior muscles was analyzed.ResultsPlantarflexion maximal torque was significantly higher for the able-bodied group (115±39 Nm) than for the group with a transfemoral amputation (77±34 Nm) (P<.01), and did not differ between able-bodied group and the group with a transtibial amputation (97±26 Nm) (P=.25). Furthermore, the transfemoral amputee group was 29% less steady than the able-bodied group (P=.01). However, there were no significant differences in torque steadiness between the able-bodied group and transtibial amputee group (P=.26) or between transtibial and transfemoral amputee groups (P=.27). The amputation had no significant effect between groups on dorsiflexion maximal torque (P=.10), gastrocnemius medialis electromyography (EMG) (P=.85), tibialis anterior coactivation (P=.95), and coactivation ratio (P=.75).ConclusionThe present study suggests that as the level of amputation progresses from below the knee to above the knee, the effect on the intact ankle is progressively more negative.     

Insights into amputee running. A muscle work analysis.

Five young, active, unilateral below knee amputees wearing the SACH prosthetic foot, and six normal subjects participated in the study. Subjects ran at a controlled velocity of 2.8 m/s +/- 10% over a ground reaction force plate while being filmed with a video camera. Joint moments, power outputs and mechanical work characteristics were then calculated. During stance phase the amputee prosthetic limb exhibited a marked reduction in total work. There was a reduction in the mechanical work at the knee and the prosthetic foot/ankle with a compensatory increase in mechanical work by the hip musculature. The intact stance phase limb mechanical work characteristics were not significantly different from normal. The hip flexors were the only muscle group in the swing phase prosthetic limb with a significant increase in muscle work compared with normal subjects. The intact swing phase limb in contrast exhibited a marked increase in concentric muscle work by the hip flexors and eccentric muscle work by the knee flexors in early swing phase, and an increase in concentric hip extensor and eccentric knee flexor muscle work in late swing phase. The major compensatory patterns, therefore, that allow below knee amputees to run appear to be an increase in stance phase hip muscle work on the prosthetic limb and increased hip and knee muscle work on the intact limb during swing phase.     

Gender differences in balance performance at the time of retirement

BACKGROUND: Impairments in balance performance are a commonly accepted risk factor for falling in older people. Since there is a higher reported incidence of falling in women, it is of interest to test whether this correlates with poorer balance performance in women than men at the time of retirement in order to plan health promotional strategies. The purpose of this study was to investigate whether any gender differences exist in balance performance in people approaching retirement age. METHODS: Ninety-seven healthy volunteers (44 males, 53 females) planning to retire shortly were enrolled in the study (age range 50-67 years). Balance assessments during quiet standing were performed under various conditions; feet together eyes open, feet together eyes closed and single limb stance eyes open. The range of centre of pressure displacement in both the anterior-posterior and medial-lateral planes was collected for each task using a force platform. FINDINGS: For several of the balance tasks the men exhibited a statistically significant larger range of centre of pressure displacement than the women (P<0.01). However, after normalising the data for height, no gender differences were seen. Over half of the group failed to complete all three single limb stance trials on both limbs. INTERPRETATION: When the data was normalised for height, no differences were found in static balance performance between men and women of retirement age. A number of participants demonstrated balance impairments whilst performing the single limb stance likely to affect functional activities. Health promotional messages should be targeted equally at men and women.     

The prevalence,distribution, and functional importance of lower limb somatosensory impairments in chronic stroke survivors: a cross sectional observational study

Purpose: To investigate the prevalence and distribution of lower limb somatosensory impairments in community dwelling chronic stroke survivors and examine the association between somatosensory impairments and walking, balance, and falls.

Methods: Using a cross sectional observational design, measures of somatosensation (Erasmus MC modifications to the (revised) Nottingham Sensory Assessment), walking ability (10?m walk test, Walking Impact Scale, Timed “Get up and go”), balance (Functional Reach Test and Centre of Force velocity), and falls (reported incidence and Falls Efficacy Scale-International), were obtained.

Results: Complete somatosensory data was obtained for 163 ambulatory chronic stroke survivors with a mean (SD) age 67(12) years and mean (SD) time since stroke 29 (46) months. Overall, 56% (n?=?92/163) were impaired in the most affected lower limb in one or more sensory modality; 18% (n?=?30/163) had impairment of exteroceptive sensation (light touch, pressure, and pin-prick), 55% (n?=?90/163) had impairment of sharp-blunt discrimination, and 19% (n?=?31/163) proprioceptive impairment. Distal regions of toes and foot were more frequently impaired than proximal regions (shin and thigh). Distal proprioception was significantly correlated with falls incidence (r?=?0.25; p?<?0.01), and centre of force velocity (r?=?0.22, p?<?0.01). The Walking Impact Scale was the only variable that significantly contributed to a predictive model of falls accounting for 15–20% of the variance.

Conclusion: Lower limb somatosensory impairments are present in the majority of chronic stroke survivors and differ widely across modalities. Deficits of foot and ankle proprioception are most strongly associated with, but not predictive, of reported falls. The relative contribution of lower limb somatosensory impairments to mobility in chronic stroke survivors appears limited. Further investigation, particularly with regard to community mobility and falls, is warranted.

• Implications for Rehabilitation

• Somatosensory impairments in the lower limb were present in approximately half of this cohort of chronic stroke survivors.

• Tactile discrimination is commonly impaired; clinicians should include an assessment of discriminative ability.

• Deficits of foot and ankle proprioception are most strongly associated with reported falls.

• Understanding post-stroke lower limb somatosensory impairments may help inform therapeutic strategies that aim to maximise long-term participation, minimise disability, and reduce falls.

     

Shape and volume change in the transtibial residuum over the short term: preliminary investigation of six subjects

A preliminary investigation was conducted to characterize the magnitude and distribution of volume change in transtibial residua at two time intervals: upon prosthesis removal and at 2 week intervals. Six adult male unilateral transtibial amputee subjects, between 0.75 and 40.0 years since amputation, were imaged 10 times over a 35-minute interval with a custom residual limb optical scanner. Volume changes and shape changes over time were assessed. Measurements were repeated 2 weeks later. Volume increase on socket removal for the six subjects ranged from 2.4% to 10.9% (median 6.0% +/- standard deviation 3.6%). Rate of volume increase was highest immediately upon socket removal and decreased with time (five subjects). In four subjects, 95% of the volume increase was reached within 8 minutes. No consistent proximal-to-distal differences were detected in limb cross-sectional area change over time. Limb volume differences 2 weeks apart ranged from -2.0% to 12.6% (0.6% +/- 5.5%) and were less in magnitude than those within a session over the 35-minute interval (five subjects). Multiple mechanisms of fluid movement may be responsible for short-term volume changes, with different relative magnitudes and rates in different amputees.