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This research sought to develop a fabricable prosthetic liner that could be fabricable, intuitive, and a cost-effective means of providing advanced prosthetics in developing settings. An affordable ethyl-vinyl-acetate roll-on (AERO) liner for permitting a total surface bearing suction socket design was created and provided to a single participant for in vivo outcome measurements. The liner was fabricated from locally produced low-density ethyl-vinyl-acetate (EVA) foam. A liner fabrication process was developed and described, and one participant was provided 3 mm and 6 mm AERO liner variants for outcome evaluations. Six-minute walk test, residual limb temperature, and socket comfort score (SCS) while in AERO liner were collected. Thirty-day step counts of AERO liner with prosthesis and thermoplastic elastomer (TPE) liner with prosthesis were collected. The results of in vivo evaluations indicate increased speed, slightly higher residuum temperature, and increased comfort of the 6 mm AERO liner. Pedometer tallied step counts for the AERO liner and TPE liner prostheses were similar. The 6 mm AERO liner provided the best comfort and function of the two thicknesses in liners, and step count data indicated that the volume of patient activity was similar to when wearing the TPE liner prosthesis. Roll-on fabricable low-cost liners offer an affordable means of providing total surface bearing suction prostheses for resource limited environments (RLE). A prosthetist or technician can use the existing skills and lab to create liners.

Step counts and oxygen consumption have yet to be reported during the 2-min walk test (2MWT) test in persons with lower-limb amputations (LLA). The purpose of this study was to determine step counts and oxygen consumption during the 2MWT in LLA. Thirty-five men and women walked for two minutes as quickly as possible while wearing activity monitors (ActiGraph Link on the wrist (LW) and ankle (LA), Garmin vivofit®3 on the wrist (VW) and ankle (VA), and a modus StepWatch on the ankle (SA), and a portable oxygen analyzer. The StepWatch on the ankle (SA) and the vivofit3 on the wrist (VW) had the least error and best accuracy of the activity monitors studied. While there were no significant differences in distance walked, oxygen consumption (VO2) or heart rate (HR) between sexes or level of amputation (p > 0.05), females took significantly more steps than males (p = 0.034), and those with unilateral transfemoral amputations took significantly fewer steps than those with unilateral transtibial amputations (p = 0.023). The VW and SA provided the most accurate step counts among the activity monitors and were not significantly different than hand counts. Oxygen consumption for all participants during the 2MWT was 8.9 ± 2.9 mL/kg/min, which is lower than moderate-intensity activity. While some may argue that steady-state activity has not yet been reached in the 2MWT, it may also be possible participants are not walking as fast as they can, thereby misclassifying their performance to a lower standard.

Validation testing is a necessary step for inertial measurement unit (IMU) motion analysis for research and clinical use. Optical tracking systems utilize marker models which must be precise in measurement and mitigate skin artifacts. Prosthesis wearers present challenges to optical tracking marker model choice. Seven participants were recruited and underwent simultaneous motion capture from two marker sets; Plug in Gait (PiG) and the Strathclyde Cluster Model (SCM). Variability of joint kinematics within and between subjects was evaluated. Variability was higher for PiG than SCM for all parameters. The within-subjects variability as reported by the average standard deviation (SD), was below 5.6° for all rotations of the hip on the prosthesis side for all participants for both methods, with an average of 2.1° for PiG and 2.5° for SCM. Statistically significant differences in joint parameters caused by a change in the protocol were evident in the sagittal plane (p < 0.05) on the amputated side. Trans-tibial gait analysis was best achieved by use of the SCM. The SCM protocol appeared to provide kinematic measurements with a smaller variability than that of the PiG. Validation studies for prosthesis wearer populations must reconsider the marker protocol for gold standard comparisons with IMUs.

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