Those with lower-limb amputations exhibit high rates of joint pain and disease, such as osteoarthritis, in their intact limb and overloading of their sound side limb during daily activities may be a contributing factor. Though limb loading biomechanics have been extensively studied during walking, fewer investigations into limb loading during other functional movements presently exist.
Researchers conducted a study that was designed to characterize the lower-limb loading of transtibial prosthesis users during three common daily tasks: sit-to-stand, squatting, and lifting.
Eight unilateral transtibial prosthesis users performed sit-to-stand (from three chair heights), squatting, and lifting a 22-lb. box. Peak vertical ground reaction forces and peak knee flexion moments were computed for each limb (sound side and prosthetic) to characterize limb loading and asymmetry. Ranges of motion of the sound side and prosthetic ankles were also quantified.
Researchers found that users had greater peak ground reaction forces and knee flexion moments in their sound side limb for all tasks (p < 0.02). On average, the sound side limb had 36–48 percent greater peak ground reaction forces and 168–343 percent greater peak knee flexion moments compared to the prosthetic limb. The prosthetic ankle provided <10-degree of ankle range of motion for all tasks, less than half the range of motion provided by the sound side ankle, the study found.
Researchers determined that prosthesis users overloaded their sound side limb during all tasks. This asymmetric loading may lead to an accumulation of damage to the intact limb joints, such as the knee, and may contribute to the development of osteoarthritis. Prosthetic design and rehabilitation interventions that promote more symmetric loading should be investigated for these tasks, the researchers concluded.
The study “Unilateral transtibial prosthesis users load their intact limb more than their prosthetic limb during sit-to-stand, squatting, and lifting” was published in the journal Clinical Biomechanics.
