Mechanical load applied by Intraosseous Transcutaneous Amputation Prosthesis (ITAP)
Description
Walking on level and sloped treadmill M, N and P data sets. Also included are data from Sitting and rising from stool (Q) and Step over block (R). Data collected from one participant: The participant was a 50 year old male with a left transfemoral amputation (residuum = 181 mm measured from greater trochanter proximal ridge) as a result of trauma in 1984, he provided full informed consent for this study. He had used a prosthetic socket until he received an ITAP in 2012 as part of a clinical trial (Identifier = NCT02491424). The ITAP spigot (the percutaneous part of the POI) connected to a failsafe release device, which protects the bone from overload (now withdrawn Fail-Safe Attachment for Prosthetic Limb, patent GB2479532A, Stanmore Implants Worldwide, Hertfordshire, UK). The failsafe connected to a microprocessor controlled Genium knee, which connected to a mechanical carbon fibre Taleo foot (both Ottobock, Duderstadt, Germany) using standard prosthetic fittings. He was 1.89 m tall and weighed 102.8 kg (including the 1.4 kg artificial leg and all prosthetic components) with a K3 prosthetic activity level. Kinetic data collection: Uphill, level and downhill gait data was collected on a treadmill (GRAIL Motek, Amsterdam, The Netherlands) at a self-selected speed and gradient. The uphill and downhill gradients were 8.5 ° and 7.0 ° respectively. Level and downhill walking was at 1.0 m/s; uphill walking was at 0.8 m/s. The participant walked untethered without the use of handrails in level walking and intermittently on the slopes, and after fitting the load cell, acclimatised to the treadmill conditions for 20 minutes prior to measurement. Load cell construction: A prosthetic tube connecting the participant’s artificial knee to a failsafe device was replaced with an instrumented tube (load cell). The load cell contained 20 thin film strain gauges oriented such as to be sensitive to the DOF to be measured, having five thin film strain gauges located on each of four sides. Gauges (20 kOhms) were wire bonded to a flexible printed circuit which interconnected the four quadrants. Electrically, these formed six half bridges of gauges wired for primary sensitivity to axial compression, AP bending and ML bending. Four gauges at 45 ° to the long axis were wired into four channels of quarter bridge action only, for primary sensitivity to shear force and torque. It was accepted that there would be cross-talk between channels wired primarily for one DOF, as is usually the case where gauges are shared between DOF’s, and the matrix method of calibration was therefore used to identify and appropriately combine channels sensitive to more than one applied load type. Each channel was wired to a printed circuit for amplification, A-D conversion, serial data streaming and radio transmission