Measurement of biomechanical interactions at the stump-socket interface in lower limb prostheses

Abstract

This paper introduces a novel measuring approach for detecting relative movement between stump and socket in lower limb prostheses. The application of the motion capturing based measuring approach is shown at a single male trans-tibial amputee using a Patella Tendon Bearing (PTB) socket. It further investigates and assesses the feasibility of measuring the relative movement between stump and socket during level walking at different velocities and allocating it to the coinciding loads. Representative results for the two translational degrees of freedom in the sagittal plane are presented and discussed. For the proximodistal (pd) direction, a linear correlation between applied load and relative movement is found, while for the anteroposterior (ap) direction the stump movement is largely influenced by the motion sequence during the respective gait event. Additionally, the effect of walking speed is discussed.

Systematic Experimental Assessment of a 2D-Motion Sensor to Detect Relative Movement between Residual Limb and Prosthetic Socket

“…Magnitude, velocity, and acceleration of relative movement between residual limb and prosthetic socket are expected to depend on gait dynamics and subsequent induced loads [ 20 ]. The maximal detectable velocity and acceleration of approximately 3810 mm/s, respectively 294,300 mm/s 2 of the sensor exceed expected gait dynamics ( mm/s and mm/s 2 cf.…”

“…The maximal detectable velocity and acceleration of approximately 3810 mm/s, respectively 294,300 mm/s 2 of the sensor exceed expected gait dynamics ( mm/s and mm/s 2 cf. [ 20 ]).…”

“…The two levels of the test rig movement factors are set by considering the biomechanics at the interface: relative movements can be as little as 5 mm while the maximum gradient can be estimated to 71 mm/s [ 20 ]. To account for the most challenging measurement situations, the values for minimal distance is set to 1 mm while the maximal velocity is set to 100 mm/s.…”

“…With the established experimental setup, a gait-induced motion similar to the expected relative movement between residual limb and prosthetic socket during gait (cf. [ 20 ]) is achieved.…”

“…However, measuring relative movement between residual limb and prosthesis is still a remarkable challenge and approaches suggested in the literature vary distinctly regarding geometrical definitions, measurement principles, and the considered load conditions. The most common techniques that are used to acquire relative movement data at the interface are: radiography [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], ultrasound [ 17 , 18 , 19 ], motion capture [ 20 , 21 , 22 ], and other optical means [ 23 , 24 , 25 , 26 ]. Recently, the correlation between fluctuations in vacuum pressure of elevated vacuum suspension systems and the amount of distal displacement have been investigated and shown to be correlated [ 27 , 28 ].…”