Development of a physical mobility prediction model to guide prosthetic rehabilitation.

BACKGROUND: Prosthetic rehabilitation decisions depend on estimating a patient's mobility potential. However, no validated prediction models of mobility outcomes exist for people with lower-limb amputation (LLA). OBJECTIVES: To develop and test predictions for self-reported mobility after LLA, using the Prosthetic Limb Users Survey of Mobility (PLUS-M). STUDY DESIGN: This is a retrospective cohort analysis. METHODS: Eight hundred thirty-one patient records (1,860 PLUS-M observations) were used to develop and test a neighbors-based prediction model, using previous patient data to predict the 6-month PLUS-M T-score trajectory for a new patient (based on matching characteristics). The prediction model was developed in a training data set (n = 552 patients) and tested in an out-of-sample data set of 279 patients with later visit dates. Prediction performance was assessed using bias, coverage, and precision. Prediction calibration was also assessed. RESULTS: The average prediction bias for the model was 0.01 SDs, average coverage was 0.498 (ideal proportion within the 50% prediction interval = 0.5), and prediction interval was 8.4 PLUS-M T-score points (40% improvement over population-level estimates). Predictions were well calibrated, with the median predicted scores falling within the standard error of the median of observed scores, across all deciles of the data. CONCLUSIONS: This neighbors-based prediction approach allows for accurate estimates of PLUS-M T-score trajectories for people with LLA.

Falls After Dysvascular Transtibial Amputation: A Secondary Analysis of Falling Characteristics and Reduced Physical Performance.

INTRODUCTION: Over half of all people with lower limb amputation (LLA) experience at least one fall annually. Furthermore, the majority of LLAs result from dysvascular health complications, contributing to balance deficits. However, fall-related research specific to dysvascular LLA remains limited. OBJECTIVE: To characterize falls among adults with dysvascular LLA, using an existing Fall-Type Classification Framework and to describe the functional characteristics of participants across the framework categories. DESIGN: Secondary data analysis from two randomized controlled trials. SETTING: Outpatient setting. PARTICIPANTS: People (n = 69) 6 months to 5 years from dysvascular lower extremity amputation, who were ≥50 years of age and independently ambulatory using a prosthesis. INTERVENTION: None. OUTCOME: Descriptions of self-reported falls were collected on a weekly basis for 12 weeks, and analyzed using an existing Fall-Type Classification Framework. Fall frequencies, estimated count, and estimated proportions were compared across all framework categories, with 95% confidence intervals. Functional measures (Timed Up and Go, Two Minute Walk, Five Meter Walk, and average step count) were collected, and averages for each participant who experienced a fall were calculated. RESULTS: Thirty participants (43.5%) reported 42 falls within 12 weeks. A variety of fall types were described. Incidence of falls was highest for intrinsic destabilization sources, from incorrect weight shift patterns during transfer activities. CONCLUSION: Patients with dysvascular LLAs experience a variety of fall types. The high frequency of intrinsically sourced, incorrect weight-shift falls during transfer activities emphasizes the need to focus rehabilitation efforts on improving postural control in patients with dysvascular LLAs during activities such as reaching, turning, and transferring.

Physical Function and Pre-Amputation Characteristics Explain Daily Step Count after Dysvascular Amputation.

BACKGROUND: People with dysvascular lower limb amputation (LLA) achieve one-third of the recommended steps per day and experience severe disability. Although physical function improves with rehabilitation after dysvascular LLA, physical activity remains largely unchanged, and factors contributing to limited daily step count are unknown. OBJECTIVES: To identify factors that contribute to daily step count after dysvascular LLA. DESIGN: Cross-sectional, secondary data analysis. SETTING: Outpatient rehabilitation facilities. PARTICIPANTS: Fifty-eight patients with dysvascular major LLA (age: 64 ± 9 years, body mass index: 30 ± 8 kg/m2 , male: 95%, transtibial LLA: 95%). METHODS: Data were collected by a blinded assessor after dysvascular LLA. Candidate explanatory variables included (1) demographics, (2) LLA characteristics, (3) comorbidities and health behaviors, and (4) physical function. Variables with univariate associations with log steps/day (transformed due to non-normality) were included in a multiple linear regression model using backward elimination to identify factors that explained significant variability in log steps/day. PRIMARY OUTCOME MEASURE: The primary outcome, daily step count, was measured with accelerometer-based activity monitors worn by participants for 10 days. RESULTS: Participants took an average (± SD) of 1450 ± 1309 steps/day. After backward elimination, the final model included four variables explaining 62% of the overall daily step count (P < .0001): 2-minute walk distance (32%), assistive device use (11%), cardiovascular disease (10%), and pre-amputation walking time (11%). CONCLUSIONS: Average daily step count of 1450 steps/day reflects the lowest category of sedentary behavior. Physical function, cardiovascular disease, and pre-amputation walking time explain 62% of daily step count after dysvascular LLA. Although physical rehabilitation commonly focuses on improving physical function, interventions to increase daily step count after dysvascular LLA should also consider chronic disease and health behaviors that predate LLA. LEVEL OF EVIDENCE: III.