Does Unilateral Lower Limb Amputation Influence Ankle Joint Torque in the Intact Leg?

Area of Science:

• Biomechanics
• Rehabilitation Science
• Prosthetics and Orthotics

Background:

• Unilateral lower limb amputation significantly impacts functional mobility and biomechanics.
• The intact limb compensates for the loss of function, but its capacity and potential long-term effects are not fully understood.
• Ankle function in the intact limb is crucial for balance, gait, and overall physical activity.

Purpose of the Study:

• To investigate and compare ankle torque and steadiness in the intact leg of individuals with unilateral transtibial and transfemoral amputations.
• To determine if the level of amputation influences the functional capacity of the contralateral limb's ankle.

Main Methods:

• A comparative study involving 37 participants: 15 transfemoral amputees, 8 transtibial amputees, and 14 able-bodied controls.
• Maximal isometric ankle plantarflexion and dorsiflexion torque were measured in the intact limb (amputees) and dominant limb (controls).
• Torque steadiness was assessed using the coefficient of variation (CV) during submaximal isometric plantarflexion, and electromyographic (EMG) activity of key ankle muscles was analyzed.

Main Results:

• Transfemoral amputees demonstrated significantly lower maximal plantarflexion torque and reduced torque steadiness compared to able-bodied individuals.
• No significant differences in maximal plantarflexion torque or steadiness were found between transtibial amputees and able-bodied controls.
• Maximal dorsiflexion torque, muscle EMG activity, and coactivation patterns showed no significant differences across all groups.

Conclusions:

• Higher levels of amputation (transfemoral) appear to have a more detrimental effect on the intact ankle's torque production and steadiness.
• Transtibial amputation may have a less pronounced impact on the contralateral ankle's functional capacity.
• These findings highlight the importance of considering amputation level when assessing and managing the biomechanical adaptations in the intact limb.