375 JRRD JRRD Volume 46, Number 3, 2009 Pages 375–384 Journal of Rehabilitation Research & Development Transtibial amputee joint rotation moments during straight-line walking and a common turning task with and without a torsion adapter Ava D. Segal, MS; 1–2 Michael S. Orendurff, MS; 1 Joseph M. Czerniecki, MD; 1,3 Jane B. Shofer, MS; 1 Glenn K. Klute, PhD 1–2,4* 1 Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, Rehabilitation Research and Development Service, Department of Veterans Affairs Puget Sound Health Care System, Seattle, WA; 2 Departments of Mechanical Engineering, 3 Rehabilitation Medicine, and 4 Electrical Engineering, University of Washington, Seattle, WA Abstract—Amputees lack movement and control mechanisms at the foot and ankle that result in different strategies for loco- motion than nonamputees. The torsion adapter is a prosthetic device designed to minimize shear stress at the residual limb by facilitating rotation in the transverse plane. This study deter- mined if the addition of a torsion adapter alters lower-limb joint rotation moments of transtibial amputees walking in a straight line and turning. Ten transtibial amputees wore either a torsion adapter or a rigid adapter for an acclimation period of 3 weeks in random order. Ten nonamputees were also included for com- parison. Kinetics were collected as participants walked in a straight line and around a 1 m-radius circular path at their self- selected turning walking speed. When amputee participants wore the torsion adapter, they demonstrated decreased pros- thetic-limb peak internal rotation moments at the inside limb knee and hip compared with when they wore the rigid adapter, which may facilitate changes in orientation by not actively resisting the turn. Nonamputees exhibited larger moments com- pared with the prosthetic limb for both the amputee participants wearing either the torsion or rigid adapters. No differences were found in the moments for the intact limb between torsion and rigid adapter conditions during turning and for both limbs during straight-line walking. Key words: amputee, kinetics, moment, prosthesis, rehabilita- tion, rotation, torque, torsion adapter, transtibial, transverse plane, turning. INTRODUCTION Discomfort and residual-limb pain are two main con- cerns for lower-limb amputees [1]. These problems are often derived from transmitted loads that occur during ambulation and may be exacerbated with turning gait. Turning is quite prevalent in daily ambulation [2–3] and is especially important to the household ambulator who is mobility impaired and whose daily step count mostly comprises short bouts of walking with frequent changes of direction [4]. These individuals have more difficulty turning, since they take more time and steps to complete a turn [5–7] and fall more frequently, resulting in injuries [8–9]. Turning is likely more difficult for lower-limb amputees because of their inability to modulate trans- verse plane joint torque, one of the turning mechanisms for nonamputees [10]. Because amputees have a portion Abbreviations: NA = nonamputee (participants), RA = (ampu- tee participants wearing) rigid adapter, SD = standard deviation, TA = (amputee participants wearing) torsion adapter. * Address all correspondence to Glenn K. Klute, PhD; Department of Veterans Affairs Puget Sound Health Care System, 1660 S Columbian Way, MS-151, Seattle, WA 98108; 206-277-6724; fax: 206-764-2808. Email: gklute@u.washington.edu DOI:10.1682/JRRD.2008.06.0070