Study design Qualitative study Background Input from target respondents in the development of patient-reported outcome measures (PROMs) is necessary to ensure that the instrument is meaningful. Objectives To solicit perspectives of prosthetic limb users about their mobility experiences and to inform development of the Prosthetic Limb Users Survey of Mobility (PLUS-M). Methods Four focus groups of lower limb prosthesis users were held in different regions of the United States. Focus group transcripts were coded and themes were identified. Feedback from participants was used to develop a framework for measuring mobility with a lower limb prosthesis. Results Focus group participants (n=37) described mobility as a confluence of factors that included characteristics of the individual, activity, and environment. Identified themes were defined as individual characteristics, forms of movement, and environmental situations. Prosthetic mobility was conceptualized as movement activities performed in an environmental or situational context. Conclusions Respondent feedback used to guide development of PLUS-M established a foundation for a new person-centered measure of mobility with a prosthetic limb.

Abstract-This research compares transtibial prosthetic sockets made by central fabrication facilities with their corresponding American Academy of Orthotists and Prosthetists (AAOP) electronic shape files and assesses the central fabrication process. We ordered three different socket shapes from each of 10 manufacturers. Then we digitized the sockets using a very accurate custom mechanical digitizer. Results showed that quality varied considerably among the different manufacturers. Four of the companies consistently made sockets within +/-1.1% volume (approximately 1 sock ply) of the AAOP electronic shape file, while six other companies did not. Six of the companies showed consistent undersizing or oversizing in their sockets, which suggests a consistent calibration or manufacturing error. Other companies showed inconsistent sizing or shape distortion, a difficult problem that represents a most challenging limitation for central fabrication facilities.

Purpose Measuring constructs such as mobility with patient-reported outcomes (PROs) can enhance clinical and scientific understanding of how health conditions, like lower limb amputation, impact patients’ lives. When developing PRO questionnaires, cognitive interviews (CIs) are used to examine if survey items are understandable, clear, and meaningful. The aim of this study was to use CIs to inform item development for the Prosthetic Limb Users Survey of Mobility (PLUS-M), a PRO that measures mobility in prosthetic limb users. Methods Thirty-six CIs were conducted with 30 prosthetic limb users. Each participant responded to up to 30 items from the PLUS-M candidate item set. Each item was reviewed by a minimum of five participants who differed in self-reported mobility, literacy, level of amputation, and time since amputation. Items were revised based on participant feedback and substantially revised items were re-evaluated through additional CIs. Results Feedback from CIs identified substantial issues in 76 of the total 156 items. These items were subsequently modified or eliminated. Conclusion CIs were an essential qualitative step in the development of the PLUS-M item bank and resulted in better functioning items.

Abstract-We investigated electrical bioimpedance as a potential measurement modality to assess residual-limb volume change in lower-limb amputees. Four strip electrodes were positioned across the anterior lateral to posterior lateral aspects of the proximal lower leg or residual limb such that the outer pair applied current and the inner pair sensed voltage. A commercial bioimpedance analyzer supplied current at 50 frequencies between 5 kHz and 1 MHz and then used a wellvalidated model to determine fluid resistance. From these data, extracellular fluid volume (V ECF ) could be estimated. Bench test evaluation showed the instrument to have a root-meansquare error of less than 0.014% over a 1 h interval. Tests of subjects who had been transtibial amputees for at least 2 yr showed V ECF changes from postural adjustments well outside the instrument error and normal minute-to-minute biological variability. The rate of V ECF change while standing with the prosthesis donned was greater for diabetic subjects than for nondiabetic subjects. Bioimpedance analysis may have use in prosthetics research, where comparing residual-limb volume at different time points or under different treatment conditions is of interest.