Transtibial amputee joint rotation moments during straight-line walking and a common turning task with and without a torsion adapter

Amputees lack movement and control mechanisms at the foot and ankle that result in different strategies for locomotion 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 determined 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 comparison. 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 prosthetic-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 compared 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.