Enhancement of a prosthetic knee with a microprocessor-controlled gait phase switch reduces falls and improves balance confidence and gait speed in community ambulators with unilateral transfemoral amputation

BACKGROUND: Despite the evidence for improved safety and function of microprocessor stance and swing-controlled prosthetic knees, non-microprocessor-controlled prosthetic knees are still standard of care for persons with transfemoral amputations in most countries. Limited feature microprocessor-control enhancement of such knees could stand to significantly improve patient outcomes. OBJECTIVES: To evaluate gait speed, balance, and fall reduction benefits of the new 3E80 default stance hydraulic knee compared to standard non-microprocessor-controlled prosthetic knees. STUDY DESIGN: Comparative within-subject clinical study. METHODS: A total of 13 young, high-functioning community ambulators with a transfemoral amputation underwent assessment of performance-based (e.g. 2-min walk test, timed ramp/stair tests) and self-reported (e.g. falls, Activities-Specific Balance Confidence scale, Prosthesis Evaluation Questionnaire question #1, Satisfaction with the Prosthesis) outcome measures for their non-microprocessor-controlled prosthetic knees and again after 8 weeks of accommodation to the 3E80 microprocessor–enhanced knee. RESULTS: Self-reported falls significantly declined 77% (p = .04), Activities-Specific Balance Confidence scores improved 12 points (p = .005), 2-min walk test walking distance increased 20 m on level (p = .01) and uneven (p = .045) terrain, and patient satisfaction significantly improved (p < .01) when using the 3E80 knee. Slope and stair ambulation performance did not differ between knee conditions. CONCLUSION: The 3E80 knee reduced self-reported fall incidents and improved balance confidence. Walking performance on both level and uneven terrains also improved compared to non-microprocessor-controlled prosthetic knees. Subjects’ satisfaction was significantly higher than with their previous non-microprocessor-controlled prosthetic knees. The 3E80 may be considered a prosthetic option for improving gait performance, balance confidence, and safety in highly active amputees. CLINICAL RELEVANCE: This study compared performance-based and self-reported outcome measures when using non-microprocessor and a new microprocessor-enhanced, default stance rotary hydraulic knee. The results inform rehabilitation professionals about the functional benefits of a limited-feature, microprocessor-enhanced hydraulic prosthetic knee over standard non-microprocessor-controlled prosthetic knees.