Gait asymmetry is associated with performance-based physical function among adults with lower-limb amputation.

BACKGROUND: Adults with lower-limb amputation walk with an asymmetrical gait and exhibit poor functional outcomes, which may negatively impact quality-of-life. OBJECTIVE: To evaluate associations between gait asymmetry and performance-based physical function among adults with lower-limb amputation. METHODS: A cross-sectional study involving 38 adults with a unilateral transtibial (N = 24; 62.5 ± 10.5 years) or transfemoral amputation (N = 14; 59.9 ± 9.5 years) was conducted. Following gait analysis (capturing step length and stance time asymmetry at self-selected (SSWS) and fast walking speeds (FWS)), participants completed performance-based measures (i.e. Timed Up and Go (TUG), the 10-Meter Walk Test (10mwt), and the 6-Minute Walk Test (6MWT)). RESULTS: Step length and stance time asymmetry (at SSWS and FWS) were significantly correlated with each performance-based measure (p < .001 to p = .035). Overall, models with gait measures obtained at SSWS explained 40.1%, 46.8% and 40.1% of the variance in TUG-time (p = .022), 10mwt-speed (p = .003) and 6MWT-distance (p = .010), respectively. Models with gait measures obtained at FWS explained 70.0%, 59.8% and 51.8% of the variance in TUG-time (p < .001), 10mwt-speed (p < .001), and 6MWT-distance (p < .001), respectively. CONCLUSIONS: Increases in step length or stance time asymmetry are associated with increased TUG-time, slower 10mwt-speed, and reduced 6MWT-distance. Findings suggest gait asymmetry may be a factor in poor functional outcomes following lower-limb amputation.

Trunk Muscle Characteristics: Differences Between Sedentary Adults With and Without Unilateral Lower Limb Amputation.

OBJECTIVE: The primary purpose of this study was to compare trunk muscle characteristics between adults with and without unilateral lower limb amputation (LLA) to determine the presence of modifiable trunk muscle deficits (ie, impaired activity, reduced volume, increased intramuscular fat) evaluated by ultrasonography (US) and magnetic resonance imaging (MRI). We hypothesized that compared with adults without LLA (controls), individuals with transfemoral or transtibial LLA would demonstrate reduced multifidi activity, worse multifidi and erector spinae morphology, and greater side-to-side trunk muscle asymmetries. DESIGN: Cross-sectional imaging study. SETTING: Research laboratory and imaging center. PARTICIPANTS: Sedentary adults (n=38 total) with LLA (n=9 transfemoral level; n=14 transtibial level) and controls without LLA (n=15). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We examined bilateral multifidi activity using US at levels L3/L4-L5/S1. MRI was performed using 3-dimensional quantitative fat-water imaging; bilateral L1-L5 multifidi and erector spinae were manually traced, and muscle volume (normalized to body weight) and percentage intramuscular fat were determined. Between-group and side-to-side differences were evaluated. RESULTS: Compared with adults without LLA, participants with LLA demonstrated reduced sound-side multifidi activity; those with transfemoral LLA had larger amputated-side multifidi volume, whereas those with transtibial LLA had greater sound- and amputated-side erector spinae intramuscular fat (P<.050). With transfemoral LLA, side-to-side differences in erector spinae volume, as well as multifidi and erector spinae intramuscular fat, were found (P<.050). CONCLUSIONS: Impaired trunk muscle activity and increased intramuscular fat may be modifiable targets for intervention after LLA.

Test-Retest Reliability of Dynamic Balance Performance-Based Measures Among Adults With a Unilateral Lower-Limb Amputation.

BACKGROUND: There is large variation in administration of performance-based, dynamic balance measures among adults with lower-limb amputation (LLA). Further, there has been limited exploration of test-retest reliability of these measures in adults with lower-limb loss, including whether there is a difference in reliability if one records "best" vs "average" performance across trials. OBJECTIVE: To determine test-retest reliability of several balance tests for both "best" and "average" score performance in community-dwelling adults with a unilateral LLA, including quantification of the precision of individual scores (SE of the measurement, SEM) and estimates of minimal detectable change (MDC90 ). DESIGN: Cross-sectional study. SETTING: Mobile research laboratory. PARTICIPANTS: 27 participants (55.5% female) with an average age of 51 (SD = 12.2) years, who were predominantly community-ambulators (92.5%), after a unilateral transtibial (n = 20), transfemoral (n = 5), or other major lower-extremity (n = 2) amputation, were included. Median time since amputation was 6.3 (2.3, 19 [25th, 75th interquartile range]) years. METHODS: Reliability was evaluated using intraclass correlation coefficient (ICC) models (3,1 or 3,k). SEMs and MDC90 values with 95% confidence intervals (CIs) were calculated. MAIN OUTCOME MEASURES: 360o Turn Test, 5 Times Sit-To-Stand, Functional Reach Test, Figure-of-8 Walk Test, and Four Square Step Test (FSST). RESULTS: The ICCs (3,1 or 3,k) for all tests (for both "best" and "average" performance) were considered good-to-excellent and CIs varied from 0.69 (95% CI = 0.40-0.85) to 0.97 (95% CI = 0.95-0.99). For most tests, "best" and "average" performance demonstrated similar ICC values. MDC90 values did not surpass 10% of test means for any of the measures. CONCLUSIONS: The dynamic balance measures evaluated for use among community-dwelling adults with a unilateral LLA demonstrated excellent reliability, along with high precision of scores and MDC values that did not exceed 10% of testing means. Either best or average scoring may be used when administering the majority of these tests, as long as the assessment method is appropriately documented and replicated at follow-up to allow direct comparisons. With the FSST, clinicians should consider taking the average of two FSST trials. LEVEL OF EVIDENCE: III.