Design and testing of a simple quick connect for a prosthetic liner tether.

BACKGROUND: A limitation of tether lanyards is that fastening and unfastening the tether from the liner, which needs to be performed to clean or replace the liner, is difficult for some users. OBJECTIVE: The purpose of this research was to create a quick connect that allows users to easily attach and detach the tether from the liner. STUDY DESIGN: Mechanical testing and pilot study. METHODS: A slide-and-lock mechanism was used. To operate the quick connect, the prosthesis user turns open the lock, slides it onto a short pin extending from the liner, and releases the mechanism, causing it to spring back to the locked position. RESULTS: Mechanical tests demonstrated that the system well-tolerated tensile loads of 25,000 cycles at 100 N and single cycles at 350 N. Five transtibial users trialed the system and took between 2 and 30 s to fasten and unfasten the quick connect. They found the quick connect intuitive to use, secure, relatively quiet, and stable. However, they preferred their traditional pin lock over the quick connect system, mainly because the quick connect required a multistep procedure (twist-align-slide) that they considered more complex than operating the locking pin to which they were accustomed. CONCLUSIONS: In its current form, the quick connect is likely to be used by limited community ambulators who struggle with the pin lock donning procedure. It also has potential use with powered tethers that use a motor to adjust tether length.

Distal weight bearing in transtibial prosthesis users wearing pin suspension.

Introduction: Low-level distal weight bearing in transtibial prosthesis users may help maintain perfusion and improve both proprioception and residual limb tissue health. Methods: The primary objectives of this research were to develop a sensor to continuously measure distal weight bearing, evaluate how prosthesis design variables affected weight bearing levels, and assess fluctuations in distal weight bearing during at-home and community use. Results: In-lab testing on a small group of participants wearing adjustable sockets demonstrated that if distal contact was present, when socket size was increased distal weight bearing increased and when socket size was reduced distal weight bearing decreased. During take-home use, participants accepted the distal weight bearing level set by the research team. It ranged between 1.1% and 6.4% BW for all days tested. The coefficient of variation (standard deviation/mean) ranged from 25% to 43% and was expected due in part to differences in walking style, speed, terrain, direction of ambulation, and bout duration. Two participants commented that they preferred presence of distal weight bearing to non-presence. Discussion: Next steps in this research are to develop clinical practices to determine target distal weight bearing levels and ranges, and to simplify the design of the sensor and weight bearing adjustment mechanism for clinical use.