Comparative Biomechanical Analysis of Current Microprocessor-Controlled Prosthetic Knee Joints

Bellmann M, Schmalz T, Blumentritt S. Comparative biomechanical analysis of current microprocessor-controlled prosthetic knee joints.

Objective

To investigate and identify functional differences of 4 microprocessor-controlled prosthetic knee joints (C-Leg, Hybrid Knee [also called Energy Knee], Rheo Knee, Adaptive 2).

Design

Tested situations were walking on level ground, on stairs and ramps; additionally, the fall prevention potentials for each design were examined. The measuring technology used included an optoelectronic camera system combined with 2 forceplates as well as a mobile spiroergometric system.

Setting

The study was conducted in a gait laboratory.

Participants

Subjects with unilateral transfemoral amputations (N=9; mobility grade, 3-4; age, 22-49y) were tested.

Interventions

Participants were fitted and tested with 4 different microprocessor-controlled knee joints.

Main Outcome Measures

Static prosthetic alignment, time distance parameters, kinematic and kinetic data and metabolic energy consumption.

Results

Compared with the Hybrid Knee and the Adaptive 2, the C-Leg offers clear advantages in the provision of adequate swing phase flexion resistances and terminal extension damping during level walking at various speeds, especially at higher walking speeds. The Rheo Knee provides sufficient terminal extension; however, swing phase flexion resistances seem to be too low. The values for metabolic energy consumption show only slight differences during level walking. The joint resistances generated for descending stairs and ramps relieve the contralateral side to varying degrees.When walking on stairs, safety-relevant technical differences between the investigated joint types can be observed. Designs with adequate internal resistances offer stability advantages when the foot is positioned on the step. Stumble recovery tests reveal that the different knee joint designs vary in their effectiveness in preventing the patient from falling.

Conclusions

The patient benefits provided by the investigated electronic prosthetic knee joints differ considerably. The C-Leg appears to offer the amputee greater functional and safety-related advantages than the other tested knee joints. Reduced loading of the contralateral side has been demonstrated during ramp and stair descent. Metabolic energy consumption does not vary significantly between the tested knees. Hence, this parameter seems not to be a suitable criterion for assessing microprocessor-controlled knee components.     

Satisfaction and Problems Experienced With Transfemoral Suspension Systems: A Comparison Between Common Suction Socket and Seal-In Liner

Objective

To compare a seal-in liner with the common suction socket with regards to patient satisfaction and problems experienced with the prosthesis.

Design

Retrospective survey.

Setting

A medical and engineering research center and a department of biomechanical engineering.

Participants

Men (N=90) with traumatic transfemoral amputation who used both suspension systems participated in the study.

Intervention

Two prosthetic suspension systems: a seal-in liner and common suction socket.

Main Outcome Measures

Two questionnaires were completed by each subject to evaluate their satisfaction and problems experienced with the 2 suspension systems. Satisfaction and problems with the prosthetic suspension systems were analyzed in terms of fitting, donning and doffing, sitting, walking, stair negotiation, appearance, sweating, wounds, pain, irritation, pistoning, edema, smell, sound, and durability.

Results

The study revealed that the respondents were more satisfied with a seal-in liner with regards to fitting, sitting, and donning and doffing. Overall satisfaction increased with the use of a seal-in liner compared with the suction socket (P<.05). However, satisfaction with the prosthesis showed no significant differences in terms of walking (flat and uneven surfaces), appearance, and stair negotiation. Furthermore, problems experienced differed significantly between the 2 suspension systems (P<.05). Sweating, wounds, pain, irritation, pistoning, edema, smell, and sound were less problematic with the use of a seal-in liner, whereas durability was significantly better with the suction socket.

Conclusions

The results of the survey suggest that satisfaction and problems with prosthetic suspension in persons with transfemoral amputation can be improved with a seal-in liner compared with the suction socket, provided that the durability of the liner is enhanced.     

Amputee Locomotion: Determining the Inertial Properties of Running-Specific Prostheses

Objectives

(1) To test the validity of a trifilar pendulum in estimating moments of inertia (MOIs) for running-specific prostheses (RSPs), (2) to measure inertial properties (mass, center of mass [CM] position, and MOIs) for 4 RSPs, (3) to verify the influence of the stiffness on the inertial properties of RSPs, and (4) to develop a predictive equation to estimate RSP CM positions.

Design

An aluminum block with known MOIs was used for verifying the accuracy of the trifilar pendulum MOI measurements. MOI errors were investigated by systematically misaligning the block and pendulum principal axes across a range of 1 to 10cm. Mass, CM position, and MOI were tested across 4 RSP designs with 3 stiffness categories each.

Setting

University biomechanics laboratory.

Specimens

Four different RSP designs and 3 stiffness categories per design were examined.

Interventions

Not applicable.

Main Outcome Measures

MOI errors from known values and principal axis misalignments between RSPs and pendulum; mass, CM positions, and RSP principal axis MOIs; and predictive equation CM position errors.

Results

The trifilar pendulum estimated MOIs within −6.21×10⁻⁵kg/m² (≤1% error) for a block with known MOIs. Misalignments of 1 to 5cm between the RSPs' and pendulum's CM yielded errors from .00002 to .00113 kg/m² (0.3%−59.2%). Each RSP's inertial properties are presented. MOIs about any axis varied <.004kg/m² across stiffness categories; MOIs differed up to .013kg/m² between different designs. The predictive CM equation erred between .010 and .028m when using average input values across an RSP design.

Conclusions

Trifilar pendulums can accurately measure RSP MOI. The RSP inertial properties differed slightly across stiffness categories within each design, but differed more substantially across different RSP designs. Using a predictive equation to estimate RSP CM positions can provide adequate data, but directly measuring CM positions is preferable.     

Physical Function, Gait, and Dynamic Balance of Transfemoral Amputees Using Two Mechanical Passive Prosthetic Knee Devices

Lythgo N, Marmaras B, Connor H. Physical function, gait, and dynamic balance of transfemoral amputees using two mechanical passive prosthetic knee devices.

Objective

To investigate the effect of the 3R90 and 3R92 (Otto Bock Healthcare) mechanical passive prosthetic knee devices on the physical function, gait, and dynamic balance (sudden stop and turn) of transfemoral amputees.

Design

Intervention study with crossover design.

Setting

University research center.

Participants

Men (N=5; mean age ± SD, 58.8±11.9y) with unilateral transfemoral amputation.

Intervention

Prosthetic knee joints (N=2; 3R90 and 3R92). Acclimatization ranged from 14 to 47 days (25.5±9.3d).

Main Outcome Measures

Physical function, gait, dynamic balance.

Results

The Timed Up and Go Test, 6-Minute Walk Test, and Four Square Step Test measures improved with the 3R92. Total scores on the Prosthesis Evaluation Questionnaire were similar for the 3R92 (82.0±6.3) and the participant's own or original device (83.9±4.8). These devices were rated higher than the 3R90 (65.5±16.8). Compared with the original device, gait velocity was significantly slower (5cm/s; P=.017) with the 3R92, but was unchanged for the 3R90. This difference was not considered clinically significant because the effect size was small (0.2). No other significant gait differences were found. Large temporal gait asymmetries observed with the original device remained with the 3R90 and 3R92 (step, ≈20%; single support, ≈30%; stance, ≈19%). Although no significant differences were found for the sudden-turn or sudden-stop tasks, the sudden-turn group success rates were highest with the original devices.

Conclusions

Gait and symmetry measures were unchanged. Gait speed was slower with the 3R92, but this was not considered to be clinically significant. Sudden-turn success rates generally were higher with the original devices. A crossover stepping movement was more difficult to implement than a side-stepping movement during sudden turns.     

Fitting a bilateral transhumeral amputee with utensil prostheses and their functional assessment 10 years later: a case report

Traumatic transhumeral amputations resulting from electric burn injury are uncommon and present a significant rehabilitation challenge. Compensating for loss of fine, coordinated function of the upper extremities with prostheses is difficult medically, technologically, psychologically, and socially. We followed up a patient with traumatic bilateral transhumeral amputation who was fitted with specially designed bilateral low-temperature utensil prostheses for 10 years. A bilateral utensil prosthesis consists of 2 thermoplastic sockets, an elastic harness, 2 utensil holders, and several different utensils. The characteristics of utensil prostheses are low cost, quick fabrication, and responsiveness to a patient's needs. Ten years after the patient's first prosthesis fitting, he still used these specially designed prostheses. By using these devices and his feet, the patient has regained independence in most activities of daily living and gained a new working skill.     

Differences in gait characteristics between persons with bilateral transtibial amputations, due to peripheral vascular disease and trauma, and able-bodied ambulators

Su P-F, Gard SA, Lipschutz RD, Kuiken TA. Differences in gait characteristics between persons with bilateral transtibial amputations, due to peripheral vascular disease and trauma, and able-bodied ambulators.

Objectives

To examine differences in gait characteristics between persons with bilateral transtibial amputations because of trauma and peripheral vascular disease (PVD); and to compare that with data from able-bodied controls that were previously collected and maintained in a laboratory database.

Design

Observational study of persons with bilateral transtibial amputations.

Setting

A motion analysis laboratory.

Participants

Nineteen bilateral transtibial amputees.

Intervention

No experimental intervention was performed. To standardize the effect of prosthetic foot type, subjects were fitted with Seattle Lightfoot II feet 2 weeks before quantitative gait analyses.

Main Outcome Measures

Temporospatial, kinematic, and kinetic gait data were recorded and analyzed.

Results

Results showed that the freely selected walking speeds of subjects with PVD and trauma were 0.69m/s and 1.11m/s, respectively, while that of able-bodied control subjects was 1.20m/s. When data were compared on the basis of freely selected walking speed, numerous differences were found in temporospatial, kinematic, and kinetic parameters between the PVD and trauma groups. However, when data from similar speeds were compared, the temporospatial, kinematic, and kinetic gait data demonstrated no statistically significant differences between the 2 amputee groups. Although not statistically significant, the PVD group displayed increased knee (P=.09) and hip (P=.06) flexion during the swing phase, whereas the trauma group displayed increased pelvic obliquity (P=.06). These actions were believed to represent different strategies to increase swing phase foot clearance. Also, the PVD group exhibited slightly greater hip power (P=.05) before toe-off.

Conclusions

Many of the differences observed in the quantitative gait data between the trauma and PVD groups appeared to be directly associated with their freely selected walking speed; the trauma group walked at significantly faster freely selected speeds than the PVD group. When their walking speeds were matched, both amputee groups displayed similar gait characteristics, with the exception that they might use slightly different strategies to increase foot clearance.     

Houghton Scale of prosthetic use in people with lower-extremity amputations: Reliability, validity, and responsiveness to change

OBJECTIVE: To evaluate the responsiveness to change and the floor and ceiling effects of the Houghton Scale. DESIGN: One-week and 3-month test-retest to evaluate reliability, validity, and responsiveness to change. SETTING: Amputee rehabilitation program. PARTICIPANTS: Persons (N=125) with unilateral or bilateral lower-extremity amputation who were wearing a prostheses: 1 group (n=49) for the reliability component and another group (n=76) for the responsiveness and validity component. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Responsiveness to change, ceiling and floor effects, and reliability and convergent validity. RESULTS: Evaluation of responsiveness to change (n=76) showed that the total score increased from a mean +/- standard deviation of 6.14+/-2.40 at discharge to 7.70+/-2.62 (P<.001) at follow-up 3 months later. Floor and ceiling effects were not detected for the overall score but were noted for the individual subscales. The internal consistency was moderate at discharge (Cronbach alpha=.71) and follow-up (Cronbach alpha=.70). The Houghton Scale correlated significantly, although moderately, with the physical composite score of the Medical Outcomes Study 36-Item Short-Form Health Survey (r=.393, P<.01) and the 2-minute walk test at admission (r=.620, P<.01) and discharge (r=.653, P<.01). The reliability (intraclass correlation coefficient=.96) of the Houghton Scale was high (n=49). CONCLUSIONS: The Houghton Scale is appropriately responsive to change in prosthetic use in individuals with lower-limb amputation after rehabilitation.     

Physical,mental, and social predictors of functional outcome in unilateral lower-limb amputees

OBJECTIVE: To study the value of physical, mental, and social characteristics as predictors of functional outcome of elderly amputees. DESIGN: Prospective, inception cohort study; comparisons with reference populations. SETTING: Main hospitals, rehabilitation centers, nursing homes, patients' own residence settings in 1 of the 3 northern provinces in the Netherlands. PARTICIPANTS: Forty-six patients older than 60 years, with unilateral transtibial or transfemoral amputation or knee disarticulation because of vascular disease. INTERVENTIONS: Measurement of physical, mental, and social predictors 2 and 6 weeks postamputation. MAIN OUTCOME MEASURES: The Sickness Impact Profile (SIP-68), Groningen Activity Restriction Scale (GARS), Timed up and go (TUG) test, and prosthetic use. RESULTS: A total of 15% of amputees died within the first year after amputation. Seventy percent lived independently at home 1 year postamputation. The functional level of the patients was low, as shown by high scores on the SIP-68 (mean, 23.6), GARS (mean, 41.2), and TUG test (mean, 23.9s). Functionally effective prosthetic use, as measured with the classification of Narang and Pohjolainen, was reached by 49%. For the SIP-68 scores, age, comorbidity, 1-leg balance, and the 15-word test predicted functional outcome in 69% of amputees. For the GARS score, age, 1-leg balance, and the 15-word test predicted functional outcome in 64%. For the TUG test, age and 1-leg balance predicted functional outcome in 42% of amputees. After correction for age, the only significant predictor for prosthetic use was 1-leg balance. CONCLUSIONS: Elderly patients with a leg amputation had a low functional level 1-year postamputation. An important part of functional outcome could be predicted 2 weeks after amputation by age at amputation, 1-leg balance on the unaffected limb, and cognitive impairment. Severe comorbidity probably also played a role. The results may be used in the general policy concerning leg amputees.     

A comparative study of conventional and energy-storing prosthetic feet in high-functioning transfemoral amputees

OBJECTIVE: To compare the results of gait analysis, timed walking tests, and socket comfort for transfemoral amputees wearing initially a Multiflex conventional prosthetic foot and then a Vari-Flex energy-storing prosthetic foot. DESIGN: Experimental crossover trial. SETTING: A regional prosthetic and amputee rehabilitation tertiary referral center in a teaching hospital. PARTICIPANTS: Six established unilateral transfemoral prosthetic users. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Gait analysis, a timed walking test, and a Prosthetic Socket Fit Comfort Score for each amputee wearing the Multiflex foot and then repeated wearing the Vari-Flex foot. RESULTS: Wearing the Vari-Flex foot, our subjects walked faster in the gait lab (1.38 +/- 0.13 m/s, P < .001) and took more equal step lengths at fast speed (1.063 +/- 0.05, P < .05). They also had greater peak ankle dorsiflexion at push-off on the prosthetic side (18.3 degrees +/-4.73 degrees, P<.001) and 3 times as much power from the prosthetic ankle at push-off (1.13 +/- 0.22 W/kg, P < .001). There were no significant changes in temporal symmetry or loading of the prosthetic limb, in the timed walking test with each foot, or in the comfort score. CONCLUSIONS: A transfemoral amputee who wears an energy-storing foot can have a more symmetric gait with regard to some measures of spatial symmetry, kinetics, and kinematics than one who wears a conventional foot. However, in this study important aspects such as more symmetric loading and comfort did not differ significantly between the 2 foot types.     

Bursitis,adventitious bursa,localized soft-tissue inflammation,and bone marrow edema in tibial stumps: the contribution of magnetic resonance imaging to the diagnosis and management of mechanical stress complications

OBJECTIVE: To assess the contribution of magnetic resonance imaging (MRI) in the diagnosis of tibial stump bursitis, in the establishment of differential diagnosis, and in the therapeutic management prosthetic-stump interface, mainly by adaptation of the prosthetic device. DESIGN: Two-year, prospective, consecutive series. SETTING: University-affiliated prosthetic and rehabilitation center and university department of radiology. PARTICIPANTS: A group of 17 persons with stump problems identified from a total of 139 consecutive below-knee amputees with prosthesis problems. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Clinical symptoms and MRI. RESULTS: Clinical symptoms (variable stump volume, fluctuating mass at palpation with or without mechanical pain) were suggestive of bursitis in 10 patients. MRI confirmed bursitis in 9 and identified 1 in whom clinical signs suggested neuroma, giving an incidence of 10 of 139 amputees (7.2%). MRI identified 13 sites of bursitis (adventitious bursa, 11; synovial bursitis, 2) and 5 localized areas of soft tissue inflammation. MRI showed diffuse muscular edema at 1 site of clinically suspected bursitis, and bursitis at another site of suspected neuroma. Calcified bursitis was observed in 1 case. Bone abnormalities associated with bursitis (n=7) included osteophytes or fracture (n=4) or bone marrow edema (n=3). Two asymptomatic neuromas were also identified. MRI-guided modifications of the prosthetic interface led to favorable outcome in all cases. CONCLUSION: Bursitis, adventitious bursae, and areas of localized soft-tissue inflammation are different aspects of the same disorder resulting from a mechanical conflict between the stump and the prosthesis socket. Besides contributing to diagnosis, MRI provides a precise assessment necessary for correcting the prosthesis-stump interface in a way that reduces mechanical stress and subsequently cures bursitis.     

Heterotopic Ossification in Civilians With Lower Limb Amputations

Objectives

To report the incidence of symptomatic heterotopic ossification (HO) in a defined civilian amputee population, describe its characteristics, and compare these findings to published data in military amputees.

Design

Retrospective chart analysis from July 1998 to July 2009.

Setting

Ambulatory amputee clinic within a large university medical center.

Participants

Adults with lower limb amputation (N=158).

Interventions

Not applicable.

Main Outcome Measure

Patients with symptomatic HO confirmed by radiographs.

Results

A total of 261 patients were evaluated; 158 met inclusion criteria, with 59% having traumatic etiology, 18% vascular etiology, 22% infection, and 1% tumor. Symptomatic HO was diagnosed in 36 (22.8%) patients, and 94% patients had mild HO on radiographic scoring. Rate of HO in amputations related to trauma was not increased compared with those of other etiologies. Surgical resection of the ectopic bone was required in 4 (11%) patients.

Conclusions

HO is seen commonly after civilian lower limb amputation regardless of etiology. The prevalence was less than that observed in previous reports from military populations. This is the first report estimating the prevalence of HO in adult civilian amputees.     

Effects of Mirror Feedback on Upright Stance Control in Elderly Transfemoral Amputees

Hlavackova P, Fristios J, Cuisinier R, Pinsault N, Janura M, Vuillerme N. Effects of mirror feedback on upright stance control in elderly transfemoral amputees.

Objective

To investigate the effects of mirror feedback on upright stance control in elderly transfemoral amputees.

Design

Before and after intervention trials.

Setting

University medical bioengineering laboratory.

Participants

Elderly transfemoral amputees (N=12).

Interventions

Participants were asked to stand upright, as immobile as possible, in 2 Eyes-open and Mirror-feedback experimental conditions. The latter experimental condition consisted of supplying the participants with their frontal reflection by positioning a mirror in front of them.

Main Outcome Measures

Weight-bearing symmetry and the displacements of the center of foot pressure under the nonaffected limb and the prosthetic limb.

Results

Mirror feedback did not modify weight-bearing symmetry and had different effects on the center of foot pressure displacements under the nonaffected limb and prosthetic limb: a decreased center of foot pressure surface area was observed in the Mirror-feedback condition relative to the Eyes-open condition under the nonaffected limb, whereas no significant difference between the Eyes-open condition and the Mirror-feedback condition was observed under the prosthetic limb.

Conclusions

Results suggest that elderly transfemoral amputees were able to integrate augmented visual biofeedback through the use of mirror-reflected body image to improve their upright stance control. The present findings could have implications for clinical practice and rehabilitation.     

Construct Validity and Test-Retest Reliability of the Climbing Stairs Questionnaire in Lower-Limb Amputees

de Laat FA, Rommers GM, Geertzen JH, Roorda LD. Construct validity and test-retest reliability of the Climbing Stairs Questionnaire in lower-limb amputees.

Objective

To investigate the construct validity and test-retest reliability of the Climbing Stairs Questionnaire, a patient-reported measure of activity limitations in climbing stairs, in lower-limb amputees.

Design

A cross-sectional study.

Setting

Outpatient department of a rehabilitation center.

Participants

Lower-limb amputees (N=172; mean ± SD age, 65±12y; 71% men; 82% vascular cause) participated in the study; 33 participated in the reliability study.

Interventions

Not applicable.

Main Outcome Measure(s)

Construct validity was investigated by testing 10 hypotheses: limitations in climbing stairs according to the Climbing Stairs Questionnaire will be greater in lower-limb amputees who: (1) are older, (2) have a vascular cause of amputation, (3) have a bilateral amputation, (4) have a higher level of amputation, (5) have more comorbid conditions, (6) had their rehabilitation treatment in a nursing home, and (7) climb fewer flights of stairs. Furthermore, limitations in climbing stairs will be related positively to activity limitations according to: (8) the Locomotor Capabilities Index, (9) the Questionnaire Rising and Sitting down, and (10) the Walking Questionnaire. Construct validity was quantified by using the Mann-Whitney U test, Kruskal-Wallis test, and Spearman correlation coefficient. Test-retest reliability was assessed with a 3-week interval and quantified using the intraclass correlation coefficient (ICC).

Results

Construct validity (8 of 10 null hypotheses not rejected) and test-retest reliability were good (ICC=.79; 95% confidence interval, .57-.90).

Conclusion

The Climbing Stairs Questionnaire has good construct validity and test-retest reliability in lower-limb amputees.     

Regional differences in pain threshold and tolerance of the transtibial residual limb: including the effects of age and interface material

OBJECTIVES: To compare the pain threshold (the minimum pressure inducing pain) and pain tolerance (the maximum tolerable pressure) of different regions of the residual limbs of amputees by the indentation method and to evaluate the interface pressure distribution and distortion of the skin surface on indentation by finite element (FE) analysis. DESIGN: Crossover trial. SETTING: Rehabilitation engineering center. PARTICIPANTS: Eight transtibial amputees for indentation test and 1 for FE analysis. INTERVENTIONS: The load applied to the residual limbs using a Pelite or polypropylene indenter attached to a force transducer was increased until subjects could no longer tolerate the load. An FE model was built to simulate the indentation process with the experimentally recorded pain threshold used to load the indenters against the soft tissues. MAIN OUTCOME MEASURES: Pain threshold and tolerance and interface pressure and distortion of soft tissues. RESULTS: The patellar tendon and distal end of the fibula were the best and the worst load-tolerant regions, respectively. Some regions with a thicker layer of soft tissue had lower pain thresholds and tolerance than those with a thinner tissue layer. There was a trend for pain threshold and tolerance to decrease with age. The FE model showed that the peak pressure at the skin surface was very close when both indenters were loaded against the soft tissue at pain threshold limit. CONCLUSIONS: Contrary to common beliefs, regions with a thicker layer of soft tissue did not have a higher load-tolerant ability than thin-skinned regions. Pain threshold and tolerance could be age dependent. The FE model suggests that pain is triggered when peak pressure is applied to the residual limb exceeding a certain limit.     

The effects of prosthetic foot design on physiologic measurements, self-selected walking velocity, and physical activity in people with transtibial amputation

OBJECTIVE: To investigate the physiologic differences during multispeed treadmill walking and physical activity profiles for the Otto Bock C-Walk foot (C-Walk), Flex-Foot, and solid ankle cushion heel (SACH) foot in people with transtibial amputation. DESIGN: A repeated-measures design with 3 prostheses. SETTING: Research laboratory. PARTICIPANTS: Eight men with unilateral transtibial amputation. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Physiologic responses (energy expenditure, gait efficiency, exercise intensity, rating of perceived exertion [RPE]) during multispeed treadmill walking (53.64, 67.05, 80.46, 93.87, 107.28 m/min) test were analyzed with 2-way repeated-measures analysis of variance (ANOVA). One-way ANOVA was employed to analyze foot-type differences for self-selected walking velocity (SSWV), and steps per day (daily activity). Analysis of covariance was used to analyze foot-type differences with SSWV as the covariable for the physiologic measurements. RESULTS: The C-Walk had a trend of improved physiologic responses compared with the SACH; however, no foot-type differences were statistically significant. Compared with the C-Walk and SACH, the Flex-Foot showed no significant differences in energy expenditure and gait efficiency, but significantly lower percentage of age-predicted maximum heart rate and RPE values. CONCLUSIONS: The energy storing-releasing feet appeared to have certain trends of improved gait performance compared with the SACH; however, not many objective foot-type differences were significantly noted. Further studies with a larger sample size are suggested.     

The Associations Between the Dominant and Nondominant Peak External Knee Adductor Moments During Gait in Healthy Subjects: Evidence for Symmetry

Teichtahl AJ, Wluka AE, Morris ME, Davis SR, Cicuttini FM. The associations between the dominant and nondominant peak external knee adductor moments during gait in healthy subjects: evidence for symmetry.

Objectives

There is growing interest in the role of the knee adduction moment in the pathogenesis of knee pain and osteoarthritis. It is unclear whether the knee adduction moment is similar between the dominant and nondominant legs during locomotion. This study examined whether asymmetry exists in the peak knee adductor moments during gait in healthy adults.

Design

Cross-sectional study.

Setting

Musculoskeletal Research Centre, La Trobe University, Melbourne, Victoria, Australia.

Participants

Three-dimensional Vicon gait analyses were performed for 17 healthy men and women.

Interventions

Not applicable.

Main Outcome Measures

The external dominant and nondominant peak knee adduction moments during early and late stance were analyzed to determine whether any significant differences occurred between limbs.

Results

Peak knee adductor moments for dominant and nondominant limbs were significantly correlated during early (R=0.61, P=0.009) and late (R=0.72, P=0.001) stance. After adjustment for age and sex, there was an associated 0.58 (P=0.030) and 0.98 (P=0.009) unit increase in the peak knee adduction moment in the nondominant leg, for every 1 unit increase in the dominant leg during the early and late stance phases of gait, respectively. Further evidence for symmetry was provided by the symmetry index, which was 0.04% and 0.62% for early and late stance, respectively.

Conclusions

In healthy subjects, the magnitude of the dominant limb peak external knee adduction moments during stance, and in particular late stance, appears representative of the magnitude of the moment in the nondominant limb. These findings imply symmetry between these moments and may have important implications when collecting data for limb analyses among healthy subjects. Whether gait symmetry protects against the onset of unilateral (or increases the risk for bilateral) pathological joint changes will need to be confirmed longitudinally.     

Energy cost of the case Western reserve standing neuroprosthesis

OBJECTIVE: To determine the oxygen consumption of a person with C7 American Spinal Injury Association (ASIA) grade B tetraplegia using the Case Western Reserve/Veterans Administration (CWRU/VA) standing neuroprosthesis. DESIGN: Measure the oxygen consumption and carbon dioxide production of a person with C7 ASIA grade B tetraplegia at rest, standing in the parallel bars with the CWRU/VA system on, ambulating in the parallel bars, and transferring from a wheelchair to a mat with the system on. SETTING: University medical center. PARTICIPANT: A 26-year-old man with C7 ASIA grade B tetraplegia. The subject was a recipient of the CWRU/VA standing neuroprosthesis. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Measurement of oxygen consumption and carbon dioxide production using a metabolic cart. RESULTS: Oxygen consumption of the subject was 1.22mL.kg(-1).min(-1) at rest. It was 4.7mL.kg(-1).min(-1) while standing in the parallel bars, 7.2mL.kg(-1).min(-1) while ambulating in the parallel bars, and 7.9mL.kg(-1).min(-1) when transferring from a wheelchair to a mat. CONCLUSIONS: Oxygen consumption of the subject when using the system is about 2 metabolic equivalent units, which is compatible with sustained use of the system for standing.     

Interlimb Coordination During the Stance Phase of Gait in Subjects With Stroke

Objective

To analyze the relation between contralesional and ipsilesional limbs in subjects with stroke during step-to-step transition of walking.

Design

Observational, transversal, analytical study with a convenience sample.

Setting

Physical medicine and rehabilitation clinic.

Participants

Subjects (n=16) with poststroke hemiparesis with the ability to walk independently and healthy controls (n=22).

Interventions

Not applicable.

Main Outcome Measures

Bilateral lower limbs electromyographic activity of the soleus (SOL), gastrocnemius medialis, tibialis anterior, biceps femoris, rectus femoris, and vastus medialis (VM) muscles and the ground reaction force were analyzed during double-support and terminal stance phases of gait.

Results

The propulsive impulse of the contralesional trailing limb was negatively correlated with the braking impulse of the leading limb during double support (r=−.639, P=.01). A moderate functional relation was observed between thigh muscles (r=−.529, P=.035), and a strong and moderate dysfunctional relation was found between the plantar flexors of the ipsilesional limb and the vastus medialis of the contralesional limb, respectively (SOL-VM, r=−.80, P<.001; gastrocnemius medialis-VM, r=−.655, P=.002). Also, a functional moderate negative correlation was found between the SOL and rectus femoris muscles of the ipsilesional limb during terminal stance and between the SOL (r=−.506, P=.046) and VM (r=−.518, P=.04) muscles of the contralesional limb during loading response, respectively. The trailing limb relative impulse contribution of the contralesional limb was lower than the ipsilesional limb of subjects with stroke (P=.02) and lower than the relative impulse contribution of the healthy limb (P=.008) during double support.

Conclusions

The findings obtained suggest that the lower performance of the contralesional limb in forward propulsion during gait is related not only to contralateral supraspinal damage but also to a dysfunctional influence of the ipsilesional limb.