Mobility Analysis of AmpuTees (MAAT 7): Normative Mobility Values for Lower Limb Prosthesis Users of Varying Age, Etiology, and Amputation Level

Relationship between step count and the Timed Up and Go and L-test of Functional Mobility among adults with transtibial amputation

OBJECTIVE

To explore the relationship between daily steps measured by the activPAL 3 and Fitbit Inspire 3 accelerometers and performance on the Timed Up and Go Test (TUG) and L-test of Functional Mobility (L-test) in adults with transtibial amputation.

DESIGN

Observational design.

SETTING

Six outpatient prosthetic clinics located in the United States, and the participant's home environment.

PARTICIPANTS

Adults (n=96) with unilateral transtibial amputation.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURE

Each participant wore the activPAL and Fitbit concurrently for seven days. Pearson's correlation was used to assess the relationship between daily steps from each device and TUG and L-test completion times. Regression was employed to control for sex, body mass index, age, and type 2 diabetes status.

RESULTS

Moderate negative correlations were observed between daily steps recorded by the activPAL and TUG (r=-0.52) and L-test (r=-0.51) times. Moderate negative correlations were also found between daily steps from the Fitbit Inspire 3 and TUG (r=-0.55) and L-test (r=-0.56) times. These relationships remained statistically significant with minimal influence by the included covariates.

CONCLUSIONS

Participants who performed well on the TUG and L-test tended to have higher daily steps counts, highlighting a meaningful association between clinical mobility performance and free-living physical activity. This finding provides evidence that TUG and L-test completion times may reflect both functional capacity in a clinical setting and real-world ambulatory behavior. While step counts and clinical performance measures are not interchangeable, together they offer complementary insights that can enhance the evaluation and monitoring of mobility in individuals with transtibial amputation.

The relationship of hip strength to walking and balance performance in unilateral lower limb prosthesis users differs by amputation level

BACKGROUND

Safe and efficient locomotion is a frequently stated goal of lower limb prosthesis users, for which hip strength may play a central yet poorly understood role. Additional research to identify associations between hip strength, balance, and mobility among transtibial and transfemoral prosthesis users is required.

OBJECTIVE

To test whether residual and/or intact limb isometric hip strength was associated with lower limb prosthesis users' walking speed, endurance, and balance.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PARTICIPANTS

Convivence sample of 14 transtibial and 14 transfemoral prosthesis users.

METHODS

Multiple linear regression was used to evaluate the relationship between isometric measures of residual and intact limb hip strength and walking and balance performance.

MAIN OUTCOME MEASUREMENTS

Measures of isometric hip muscle strength, including peak torque, average torque, torque impulse, and torque steadiness (i.e. consistency with which an isometric torque can be sustained) were derived from maximum voluntary hip flexion, extension, abduction and adduction torque signals collected with a motor-driven dynamometer. Walking speed, endurance, and balance were assessed by administering the 10-meter walk test, 2-minute walk test, Four Square Step Test, and Narrowing Beam Walking Test, respectively.

RESULTS

Residual limb hip extensor max torque and abductor torque steadiness explained between 51% and 69% of the variance in transtibial prosthesis users' walking speed, endurance, and balance. In contrast, intact limb hip abductor torque impulse explained between 33% and 48% of the variance in transfemoral prosthesis users' walking speed, endurance, and balance.

CONCLUSIONS

Our results suggest that unilateral transtibial and transfemoral prosthesis users' walking and balance performance may depend on different hip muscles, and different facets of hip strength. Amputation level-specific hip strength interventions may therefore be required to improve walking and balance performance in unilateral transtibial and transfemoral prosthesis users. The "intact leg strategy" adopted by transfemoral prosthesis users may be due to a variety of prosthesis and biomechanical factors that limit the efficiency with which transfemoral prosthesis users can exploit the strength of their residual limb hip muscles while walking.

Prosthesis and health-related factors of mobility in people with nontraumatic unilateral transtibial amputation

BACKGROUND

Numerous factors can affect mobility of individuals with lower limb amputation, including prosthesis-dependent, physical and psychological determinants.Objective:This study aimed to investigate the prosthesis and health-related factors of mobility in people with nontraumatic unilateral transtibial amputation.Study Design:Cross-sectional observational study.

METHODS

Individuals with nontraumatic unilateral transtibial amputation who are using a prosthetic leg were included. All participants were asked to fill out the Prosthesis Evaluation Questionnaire, 12-Item Short-Form Health Survey (SF-12), Comprehensive Lower Limb Amputee Socket Survey, and 12-item Prosthetic Limb Users Survey of Mobility. The relationships between the variables of interest and mobility were investigated using correlation coefficient analyses. Multiple regression analysis was run to investigate the impact of a set of predictor variables on mobility.

RESULTS

A total of 168 people with lower limb amputation were included. Mobility had a significant association with age, comorbidity, occupation, Prosthesis Evaluation Questionnaire score, physical and mental component scores of SF-12, subscales of the Comprehensive Lower Limb Amputee Socket Survey, educational status, amputation cause, time since amputation, time since using the prosthesis, and socket insert type. In the final model of multiple regression analysis, the Physical Component Summary score of SF-12 showed the strongest predictor of mobility (beta = 0.40, p < 0.001).

CONCLUSIONS

Nonprosthetic factors play a significant role in mobility of people with nontraumatic unilateral transtibial amputation. Although some predictors, such as age and time since amputation, are immutable, clinicians may still enhance the mobility of this population through the utilization of health-related factors, such as improving their physical activity.

A disparity in prosthetic access for Ecuadorians with lower-limb amputation

BACKGROUND

Individuals with disabilities in low- and middle-income countries face barriers to rehabilitation services, including prosthetic care. Many countries, such as Ecuador, have adapted policies toward achieving universal health care coverage. For optimal functional outcomes, understanding the physical potential of prosthetic users is critical for appropriate prosthetic services.

OBJECTIVE

To determine the association between the functional level of Ecuadorians with lower-limb amputations and the functional level of their prosthetic componentry.

STUDY DESIGN

Retrospective study.

METHODS

A data set containing functional level (K-Level) of Ecuadorians with lower-limb amputations and the K-Level of their prosthesis was analyzed.

RESULTS

A diverse cohort of 164 participants with unilateral lower-limb amputation was recruited. Most participants were male (76.8%) with transfemoral amputations (56.1%) due to traumatic causes (51.2%). There was a small, positive, and statistically significant correlation between participants' functional levels and prosthetic componentry. Participants's functional levels were typically superior (median = 3) to their prostheses' functional abilities (median = 1), and 37.2% of participants did not have a prosthesis at the time of assessment.

CONCLUSIONS

These data indicated that participants whose physical ability exceeded basic ambulation lacked access to prostheses to match their functional abilities. The detailed disparity between physical potential and prosthetic access derived from the study's analysis supports investment into high functioning prosthetic componentry and further investigation into where gaps in care exist.

Detecting Changes in Comfort, Pain, and Mobility Over Clinical Milestones for Individuals With Lower Limb Loss

BACKGROUND

Functional mobility, comfort and the absence of pain are key goals of prosthetic treatment. Outcome measures (OMs) evaluate the impact of treatment and normative and minimal detectable change (MDC) values are key to interpreting these scores and measuring treatment outcomes.

OBJECTIVES

This study seeks to 1) present practice-based normative values of four commonly used OMs at four prosthetic milestones and 2) explore the MDC of the measures over the treatment period.

METHODOLOGY

A chart review was conducted of OMs collected with individuals with lower limb loss between January 1, 2015, and December 31, 2023. This included data for individuals with unilateral transtibial (TT), transfemoral (TF) and rotationplasty (RP) amputations and bilateral transtibial amputation (BTT). OMs included the Socket Comfort Score (SCS), Pain Scale (PS), 2 Minute Walk Test (2MWT), and Prosthetic Limb Users Survey of Mobility (PLUS-M). Data were collected at four milestone time points: (1) Baseline and (2) Discharge from Rehabilitation for those in initial prosthetic rehabilitation, and (3) Initial Evaluation and (4) Definitive Delivery for those receiving a replacement socket. Normative values and MDC values were calculated.

FINDINGS

Data from 30 individuals undergoing in-patient rehabilitation and 74 individuals receiving a replacement socket were included. Practice-based normative data were different for each level of amputation and milestone and had the following ranges: SCS: 5.7 - 9.1, PS: 0.8 - 3.7, 2MWT: 68.4 - 146.3 m and PLUS-M: 38.9 - 57.3. MDC values also varied based on time in treatment (Rehabilitation: SCS = 2.5, PS = 1.6, 2MWT = 32.6, PLUS-M = 8.8; Replacement Socket: SCS = 3.1, PS = 2.6, 2MWT = 38.9, PLUS-M = 4.0). All measures had a statistically significant change over the intervention, however, no average scores changed by greater than the MDC.

CONCLUSIONS

The normative data and MDC scores demonstrate the PS & PLUS-M are useful measures of pain and mobility at all points within treatment. The 2MWT is indicated for individuals in rehabilitation, while the SCS is indicated for those receiving a replacement socket, as both effectively measure treatment goals that are particularly important for each phase of rehabilitation. This provides clinicians with practice-based evidence that enables them to interpret OM scores, a critical part of the decision-making process along the treatment journey.

Creating Adjusted Scores Targeting mobiLity Empowerment (CASTLE 1): determination of normative mobility scores after lower limb amputation for each year of adulthood

PURPOSE

As United States healthcare transitions from traditional fee-for-service models to value-based care, there is increased need to demonstrate quality care through clinical outcomes. Therefore, the purpose of this study was to create equations to calculate an expected mobility score for lower limb prosthesis users specific to their age, etiology, and amputation level to provide benchmarks to qualify good outcomes.

MATERIALS AND METHODS

A retrospective cross-sectional analysis of outcomes collected during clinical care was performed. Individuals were grouped based on amputation level (unilateral above-knee (AKA) or below-knee (BKA)) and etiology (trauma or diabetes/dysvascular (DV)). The mean mobility score (PLUS-M® T-score) for each year of age was calculated. AKAs were further stratified into having a microprocessor knee (MPK) or non-microprocessor (nMPK) for secondary analysis.

RESULTS

As expected, average prosthetic mobility declined with age. Overall, BKAs had higher PLUS-M T-scores compared to AKAs and trauma etiologies had higher scores compared to DV. For AKAs, those with a MPK had higher T-scores compared to those with a nMPK.

CONCLUSIONS

Results from this study provide average mobility for adult patients across every year of life. This can be leveraged to create a mobility adjustment factor to qualify good outcomes in lower limb prosthetic care.

Prevalence of secondary prosthesis use in lower limb prosthesis users

PURPOSE

Prostheses designed for daily use are often inappropriate for high-level activities and/or are susceptible to water damage and mechanical failure. Secondary prostheses, such as activity-specific or back-up prostheses, are typically required to facilitate uninterrupted participation in desired life pursuits. This study estimated the prevalence of secondary prosthesis use in a large, national sample of lower limb prosthesis users (LLPUs).

METHODS

We conducted a secondary analysis of survey data from three cross-sectional studies that assessed mobility in LLPUs. Descriptive statistics were used to determine the percentage of secondary prosthesis users and percentages of LLPUs that used different type(s) of secondary prosthesis(es). Secondary prosthesis users and non-users were compared to identify differences in participant characteristics between groups.

RESULTS

Of participants in the analysis (n = 1566), most (65.8%) did not use a secondary prosthesis. The most common secondary prosthesis types were back-up (19.2%) and activity-specific prostheses (13.5%). Secondary prosthesis users differed significantly from non-users with respect to gender, race, and other characteristics.

CONCLUSIONS

Results suggest that secondary prosthesis use for most LLPUs is limited and may differ based on users' demographic and clinical characteristics. Future research should determine how LLPUs' health-related quality-of-life outcomes are affected by access to and use of secondary prostheses.Implications for RehabilitationSecondary prostheses, including activity-specific, back-up, and shower prostheses, have the potential to improve function, mobility, and participation for people who use lower limb prostheses.Most lower limb prosthesis users do not use secondary prostheses, and access to these devices may be related to users' demographic and clinical characteristics.Rehabilitation professionals play a key role in facilitating prosthesis users' access to secondary prostheses and should advocate for those who need them.

Development and initial validation of the Orthotic Patient-Reported Outcomes-Mobility (OPRO-M): An item bank for evaluating mobility of people who use lower-limb orthoses

Lower limb orthoses (LLOs) are externally-applied leg braces that are designed to improve or maintain mobility in people with a variety of health conditions that affect lower limb function. Clinicians and researchers are therefore often motivated to measure LLO users' mobility to select or assess the effectiveness of these devices. Patient-reported outcome measures (PROMs) can provide insights into important aspects of a LLO user's mobility for these purposes. However, few PROMs are available to measure mobility of LLO users. Those few that exist have issues that may limit their clinical or scientific utility. The objective of this study was to create a population-specific item bank for measuring mobility of LLO users. Previously-developed candidate items were administered in a cross-sectional study to a large national sample of LLO users. Responses from study participants (n = 1036) were calibrated to a graded response statistical model using Item Response Theory methods. A set of 39 items was found to be unidimensional, locally independent, and function without bias due to characteristics unrelated to mobility. The set of final calibrated items, termed the Orthotic Patient-Reported Outcomes-Mobility (OPRO-M) item bank, was evaluated for initial evidence of convergent, divergent, and known groups construct validity. OPRO-M was strongly correlated with existing PROMs designed to measure aspects of physical function. Conversely, OPRO-M was weakly correlated with PROMs that measured unrelated constructs, like sleep disturbance and depression. OPRO-M also showed an ability to differentiate groups with expected mobility differences. Two fixed-length short forms were created from the OPRO-M item bank. Items on the short forms were selected based on statistical and clinical criteria. Collectively, results from this study indicate that OPRO-M can effectively measure mobility of LLO users, and OPRO-M short forms can now be recommended for use in routine clinical practice and research studies.

Rasch validation of the German translation of the Prosthetic Limb Users Survey of Mobility short forms in people with lower limb amputation

BACKGROUND

Prostheses are a primary rehabilitative intervention for people after lower limb amputation. To appropriately measure the effectiveness of prosthetic interventions, valid and reliable measures of prosthetic mobility are required. The Prosthetic Limb Users Survey of Mobility (PLUS-M) is a promising instrument for measuring prosthesis users' mobility. However, German translations of the PLUS-M short forms have not yet been validated.

OBJECTIVES

Rasch validation of the German translation of the PLUS-M short forms in people with lower limb amputation.

STUDY DESIGN

This study is based on a cross-sectional survey of prosthesis-using lower limb amputees from a nation-wide cohort.

METHODS

PLUS-M data (the 7-item and the 12-item shortforms; PLUS-M-7 and PLUS-M-12, respectively) from 194 lower limb prosthesis users were subjected to Rasch analysis, an advanced statistical method for assessing if the measurement properties of a questionnaire comply with a wide spectrum of psychometric requirements.

RESULTS

Analysis showed appropriate rating scale functioning, good internal construct validity (item fit), unidimensionality, and good targeting of the PLUS-M-7 and PLUS-M-12 short forms. Moreover, the greater conditional measurement precision of PLUS-M-12 (regarding higher test information and lower standard error of mobility estimates) was quantified.

CONCLUSIONS

Rasch analysis of the German translation of both PLUS-M short forms showed good psychometric qualities. In addition, our study showed that test scores from the PLUS-M-12 are more accurate. Therefore, the PLUS-M-12 is recommended for individual-level clinical applications (e.g., classification or change assessment).

Development of an item bank for measuring prosthetic mobility in people with lower limb amputation: The Prosthetic Limb Users Survey of Mobility (PLUS-M)

BACKGROUND

Achieving mobility with a prosthesis is a common post-amputation rehabilitation goal and primary outcome in prosthetic research studies. Patient-reported outcome measures (PROMs) available to measure prosthetic mobility have practical and psychometric limitations that inhibit their use in clinical care and research.

OBJECTIVE

To develop a brief, clinically meaningful, and psychometrically robust PROM to measure prosthetic mobility.

DESIGN

A cross-sectional study was conducted to administer previously developed candidate items to a national sample of lower limb prosthesis users. Items were calibrated to an item response theory model and two fixed-length short forms were created. Instruments were assessed for readability, effective range of measurement, agreement with the full item bank, ceiling and floor effects, convergent validity, and known groups validity.

SETTING

Participants were recruited using flyers posted in hospitals and prosthetics clinics across the United States, magazine advertisements, notices posted to consumer websites, and direct mailings.

PARTICIPANTS

Adult prosthesis users (N = 1091) with unilateral lower limb amputation due to traumatic or dysvascular causes.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Candidate items (N = 105) were administered along with the Patient Reported Outcome Measurement Information System Brief Profile, Prosthesis Evaluation Questionnaire - Mobility Subscale, and Activities-Specific Balance Confidence Scale, and questions created to characterize respondents.

RESULTS

A bank of 44 calibrated self-report items, termed the Prosthetic Limb Users Survey of Mobility (PLUS-M), was produced. Clinical and statistical criteria were used to select items for 7- and 12-item short forms. PLUS-M instruments had an 8th grade reading level, measured with precision across a wide range of respondents, exhibited little-to-no ceiling or floor effects, correlated expectedly with scores from existing PROMs, and differentiated between groups of respondents expected to have different levels of mobility.

CONCLUSION

The PLUS-M appears to be well suited to measuring prosthetic mobility in people with lower limb amputation. PLUS-M instruments are recommended for use in clinical and research settings.