Smart Boot Use to Measure Offloading Adherence

Wound healing is defined as complete epithelialization of the target ulcer, confirmed by standardized wound assessment. Healing status is recorded as a binary outcome (yes/no) for each participant. The proportion of participants achieving wound healing by 12 weeks is compared between randomized treatment arms.

Unit of Measure: %

Time to wound healing is defined as the number of days from randomization to confirm complete epithelialization of the target ulcer, as determined by standardized wound assessment.

Unit of Measure: Days

To evaluate participant acceptance of SmartBoot, the Technology Acceptance Model (TAM) questionnaire is administered. TAM is an intention-based framework widely used to assess user satisfaction and acceptance of new technologies. The questionnaire has 18 items: 9 assess perceived ease of use, 5 evaluate perceived benefits, 2 measure attitudes toward use, and 2 measure behavioral intention. Responses were rated on a 5-point Likert scale ranging from 0 (strongly disagree) to 4 (strongly agree). The average scores across all categories are normalized from 0 to 100; higher values indicate better acceptability. A score of 75 or higher is considered indicative of an acceptable level of program acceptance.

Unit of Measure: unit on scale

Participant dropout is defined as discontinuation from the study before completion of the Week 12 visit. The dropout rate is calculated as the percentage of randomized participants who withdrew before Week 12.

Unit of Measure: %

The average weekly adherence to offloading is assessed using a SmartBoot adherence algorithm based on device-on time during weight-bearing activity or the patient's self-reports. The algorithm reports a normalized adherence score ranging from 1 to 10, with lower scores indicating better adherence to prescribed offloading and higher scores indicating poorer adherence.

Unit of Measure: Unitless (normalized score, 1-10)

The percentage of wound area reduction healing will be defined as the percentage reduction in wound area relative to baseline and estimated over time using a longitudinal linear model. Wound area will be derived from standardized wound imaging acquired weekly. When weekly wound area measurements are missing, values will be estimated using linear interpolation. Absolute wound area values (cm²) will also be retained in the database for descriptive purposes.

• Unit of Measure: Percent reduction in wound area per week

Gait speed (m/s) is assessed using validated wearable sensor-based measurements. Change in gait speed from baseline is calculated as the average change from baseline at each monthly follow-up assessment. A higher reduction indicates slower gait and potentially a sign of lower extremity muscle atrophy in response to offloading treatment.

• Unit of Measure: m/s

• Outcome Measure Description: Postural control is assessed using validated wearable sensor-based measurements of body sway area (cm2) during quiet standing in a double-stance, eyes-open condition. Change in body sway area is calculated as the average change from baseline at each monthly follow-up assessment. A higher value can potentially be a sign of lower extremity muscle atrophy in response to offloading treatment.
• Unit of Measure: cm^2

Sleep quality is assessed using the Pittsburgh Sleep Quality Index (PSQI), which yields a global score ranging from 0 to 21, with higher scores indicating worse sleep quality. Scores greater than 5 have been used to indicate poor sleep quality and are reported here for descriptive interpretation.

Unit of Measure: Unit on scale (0-21)

Overall health is assessed using the PROMIS-29 Profile, which measures seven health domains (Physical Function, Anxiety, Depression, Fatigue, Sleep Disturbance, Ability to Participate in Social Roles/Activities, and Pain Interference). Results are reported as T-scores standardized to the U.S. general population (mean = 50, SD = 10). For Physical Function and Social Roles, higher scores indicate better health; for all other domains, higher scores indicate greater symptom burden. Scores of 60 or higher on symptom scales or 40 or lower on function scales reflect moderate-to-severe impairment and are reported descriptively.

Unit of Measure: T-score for each of 7 domains

Frailty is assessed using the Trauma-Specific Frailty Index, calculated as the proportion of accumulated health deficits, with scores ranging from 0 to 1. Higher values indicate greater frailty. A value of approximately 0.25 will be used as a reference threshold for frailty and is reported descriptively.

Unit of Measure: Unit on scale (0-1)

Frailty status is assessed using the Fried Frailty Criteria, which classify individuals based on five components. Scores range from 0 to 5, with higher scores indicating greater frailty. Categories of robust (0), pre-frail (1-2), and frail (≥3) are reported descriptively.

Unit of Measure: Unit on scale (0-5)

Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (CES-D), which yields scores ranging from 0 to 60, with higher scores indicating greater symptom burden. Scores of 16 or higher will be used to indicate elevated depressive symptoms and are reported for descriptive purposes.

Unit of Measure: Unit on scale (0-60)

Mobility is assessed using the Life-Space Questionnaire, which yields scores ranging from 0 to 120, with higher scores indicating greater mobility. Lower scores reflect more restricted life-space mobility and are reported descriptively. Scores of 60 or lower are considered restricted life-space mobility.

Unit of Measure: Unit on scale (0-120)

Fear of falling is assessed using the Falls Efficacy Scale-International (FES-I), which yields scores ranging from 16 to 64, with higher scores indicating greater concern about falling. Scores of 28 or higher will be used to reflect a high concern about falling and are reported descriptively.

Unit of Measure: Unit on scale (16-64)