The role of walking speed and leg proprioception in foot clearance for older transtibial prosthesis users

Falling is a concern for both older persons and transtibial prosthesis users (TTPUs), with older TTPUs potentially facing compounded risk. Older adults and TTPUs display foot clearance (FC) behavior that may contribute to increased tripping risk. Further, a person's knowledge of their leg orientation in space (ie proprioception) plays a role in managing FC and is affected by age and prosthesis use.

To examine the effect of walking speed on FC of older TTPUs and the relationship between FC and leg proprioception.

Twelve unilateral TTPUs and 10 age-matched able-bodied controls participated in this observational study.

Proprioception was assessed through knee joint angle replication ability. FC was recorded with optical motion capture while participants walked at self-selected normal and fast speeds. Average FC between groups was assessed using an independent t-test. A repeated-measures ANOVA assessed the effects of speed by limb on FC for each group separately. Linear regression controlling for speed assessed the association between FC and proprioception.

At both speeds, older TTPUs showed no difference in FC on their prosthetic limb compared with the nondominant limbs of controls. Both groups exhibited reduced FC when walking faster. Worse proprioception on the prosthetic side of TTPUs was associated with lower sound limb FC.

These behaviors may reflect a protective strategy of TTPUs to avoid foot collision during swing, including a desire to keep the sound limb close to the ground with poorer prosthetic limb position awareness.