Hydraulic- and Microprocessor-Controlled Ankle-Foot Prostheses for Limited Community Ambulators with Unilateral Transtibial Amputation: Pilot Study

Abstract

Introduction 

In the United States, access to microprocessor-controlled prosthetic ankles is limited to patients with lower-limb loss classified as unlimited community ambulators or greater. However, the potential benefits of these devices have not been evaluated among patients classified as household or limited community ambulators. This study examined the benefit of hydraulic- and microprocessor-controlled prosthetic ankles for patients classified as limited community ambulators.

Materials and Methods 

Four different treatment configurations were evaluated using a randomized crossover study design. These four configurations included the participant's current flexible keel (FK) prosthetic foot, an energy-storage-and-return foot (ESAR), a hydraulic ankle (HA), and a microprocessor ankle (MPA). After a 2-week accommodation period, both patient-reported and performance-based outcome measures were recorded for each ankle foot system. A StepWatch activity monitor and two-dimensional video motion analysis were also used to evaluate each system.

Results 

A single participant meeting the inclusion criteria was recruited. The patient-reported mobility and socket fit instruments were greatest with the HA system. When assessed on slopes and stairs, the MPA demonstrated benefits on hill ascent and stair descent. In considering the walking speed and perceived exertion jointly, the HA system allowed similar walking speed but lower exertion compared with fixed-ankle systems. The patient-reported low back pain and balance confidence instruments did not provide useful data for interpretation. Two-dimensional video motion analysis showed that the HA and MPA contributed to improved ankle and knee postures when ascending and descending a slope. The step activity data showed the greatest activity with the HA.

Discussion 

The results from the outcome measures showed a varying level of benefit across all four of the treatment configurations. Both the HA and MPA had favorable scores in varying performance-based outcome measures, but the HA scored the most favorable in a majority of the patient-reported outcome measures.

Conclusion 

The results show varying benefits of the microprocessor- and hydraulic-controlled prosthetic components over fixed-ankle ESAR and FK feet, based on both performance-based and patient-reported outcome measures. Further studies are needed to fully evaluate these benefits in larger sample sizes.