A clinical comparison of variable-damping and mechanically passive prosthetic knee devices

• Published in: American journal of physical medicine & rehabilitation Vol. 84; no. 8; p. 563
• Main Authors: Johansson, Jennifer L, Sherrill, Delsey M, Riley, Patrick O, Bonato, Paolo, Herr, Hugh
• Format: Journal Article
• Language: English
• Published: United States 01.08.2005
• Subjects: Adult; Amputees; Artificial Limbs; Biomechanical Phenomena; Electromyography; Female; Gait - physiology; Hip Joint - physiopathology; Humans; Knee Prosthesis; Male; Middle Aged; Prosthesis Design; Walking - physiology
• ISSN: 0894-9115
• DOI: 10.1097/01.phm.0000174665.74933.0b

Although variable-damping knee prostheses offer some improvements over mechanically passive prostheses to transfemoral amputees, there is insufficient evidence that such prostheses provide advantages at self-selected walking speeds. In this investigation, we address this question by comparing two variable-damping knees, the hydraulic-based Otto Bock C-leg and the magnetorheological-based Ossur Rheo, with the mechanically passive, hydraulic-based Mauch SNS. For each prosthesis, metabolic data were collected on eight unilateral amputees walking at self-selected speeds across an indoor track. Furthermore, kinetic, kinematic, and electromyographic data were collected while walking at self-selected speeds across a 10-m walkway in a laboratory. When using the Rheo, metabolic rate decreases by 5% compared with the Mauch and by 3% compared with the C-leg. Furthermore, for the C-leg and Rheo knee devices, we observe biomechanical advantages over the mechanically passive Mauch. These advantages include an enhanced smoothness of gait, a decrease in hip work production, a lower peak hip flexion moment at terminal stance, and a reduction in peak hip power generation at toe-off. The results of this study indicate that variable-damping knee prostheses offer advantages over mechanically passive designs for unilateral transfemoral amputees walking at self-selected ambulatory speeds, and the results further suggest that a magnetorheological-based system may have advantages over hydraulic-based designs.