Limb Health and Socket Pressure in Response to Powered Ankle Prostheses

Some estimates suggest that by 2050, as many as 3.6 million people in the United States will be living with limb loss, and at least 60% of them will have had at least a foot removed For military personnel, combat-related amputations remain one of the most common major disabling war-related injuries from modern armed conflict. Technological advancements in active prosthetic devices for individuals with transtibial amputation offer the potential for superior function in key areas that could lead to higher rates of RTD and improved quality of life. Currently intended primarily for individuals with a K-level of 3 or 4, active transtibial prostheses that provide controlled plantar/dorsiflexion in either swing (microprocessor-controlled prostheses) or late stance (prostheses with powered propulsion) are likely to become the gold standard in the future as technology continues to improve Indeed, users of these types of prostheses have higher mobility than those using any of the other four categories of prosthetic ankle-foot mechanisms for unlimited community ambulators. Note that a major insurer has recently declared microprocessor-controlled ankle-foot prostheses medically necessary for members whose functional level is 3 or above.The PROPRIO FOOT® by Ossur, is a microprocessor-controlled prosthesis that regulates the angle of ankle dorsiflexion during the swing phase. This added ankle control of these devices reduces the risk of falls by increasing toe clearance supports more natural standing posture on slopes and improves stair and slope ascent/descent capability by adapting to the change in terrain. On stairs, the PROPRIO FOOT® has been shown to improve affected leg knee kinematics (increased knee flexion) and kinetics (increased knee moment) instance. These improvements also contributed to higher interlimb symmetry reduced energetic cost of slope ascent and higher Amputee Mobility Predictor with a Prosthesis (AMPPRO) scores . Although the ankle of the PROPRIO FOOT® can be controlled in swing, the device does not have adequate power to provide an active propulsion instance. The Empower ankle by Ottobock is a powered prosthesis that provides active propulsion in late stance to mimic the positive work performed by the ankle plantar flexors in push-off. The Empower has been shown to improve affected leg kinematics (increased ankle range of motion and reduced knee flexion) on smooth flat ground ramp ascent and gravel]. In terms of kinetics, the Empower likewise results in increased ankle power on level ground stairs and ramps . Active prostheses like the PROPRIO FOOT® and Empower ankle offer great potential to more completely restore the locomotor capabilities of individuals with transtibial amputation, perhaps enhancing RTD for military personnel. As with all prosthetic components, though, these active devices are of little use if they induce pain and/or injury at the residual limb to the degree that the user will simply not wear them. The investigators will examine how optimal fit of lower limb prostheses can impact individuals comfort and/or reduce irritation.