Effects of sitting postures on risks for deep tissue injury in the residuum of a transtibial prosthetic-user: a biomechanical case study

• Published in: Computer methods in biomechanics and biomedical engineering Vol. 14; no. 11; pp. 1009 - 1019
• Main Authors: Portnoy, S., Siev-Ner, I., Shabshin, N., Gefen, A.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis Group 01.11.2011
• Subjects: Amputation - rehabilitation; Artificial Limbs; below-knee prosthesis; Biomechanical Phenomena; Connective Tissue - injuries; Finite Element Analysis; Humans; Magnetic Resonance Imaging; patient-specific finite element model; Posture; pressure ulcer; Range of Motion, Articular; Risk Assessment; Tibia; tissue injury threshold
• ISSN: 1025-5842; 1476-8259; 1476-8259
• DOI: 10.1080/10255842.2010.504719

Transtibial amputation prosthetic-users are at risk of developing deep tissue injury (DTI) while donning their prosthesis for prolonged periods; however, no study addresses the mechanical loading of the residuum during sitting with a prosthesis. We combined MRI-based 3D finite element modelling of a residuum with an injury threshold and a muscle damage law to study risks for DTI in one sitting subject in two postures: 30°-knee-flexion vs. 90°-knee-flexion. We recorded skin-socket pressures, used as model boundary conditions. During the 90°-knee-flexion simulations, major internal muscle injuries were predicted (>1000 mm 3 ). In contrast, the 30°-knee-flexion simulations only produced minor injury ( < 14 mm 3 ). Predicted injury rates at 90°-knee-flexion were over one order of magnitude higher than those at 30°-knee-flexion. We concluded that in this particular subject, prolonged 90°-knee-flexion sitting theoretically endangers muscle viability in the residuum. By expanding the studies to large subject groups, this research approach can support development of guidelines for DTI prevention in prosthetic-users.