Individuals with a trans-tibial amputation present trunk and lower limbs biomechanical asymmetry during sit-to-stand...

Individuals with a transtibial amputation (iTTA) are usually fitted with a prosthetic leg. However, it does not prevent functional limitations or compensatory strategies during daily activities, such as sit-to-stand transition (STS). Compensatory strategies may be linked to higher risk of secondary joint conditions.

This study aimed to assess compensatory strategies using kinetic asymmetry and trunk kinematics among iTTA compared with healthy counterparts during STS.

Nine iTTA and 9 healthy subjects performed 5 STS. Kinematic and kinetic data were recorded using a motion capture system, an instrumented chair, and floor-embedded force platforms. Total support moment (TSM), joint contribution to the TSM, vertical ground reaction forces (vGRF), and trunk kinematics were assessed. The TSM was calculated during each STS phase (leaning, momentum, and extension). One-way ANOVA and Games-Howell post-hoc test were used to compare limb contribution. Between-limb symmetry index (SI), for TSM joint contribution and vGRF, and trunk kinematics were compared between groups using an independent Student t-test.

During the STS, higher TSM was found in the intact lower limb of iTTA compared with their amputated limb and healthy subjects' dominant limb. Compared with healthy subjects, showing symmetrical TSM joint contribution, iTTA demonstrated higher asymmetries at each lower limb joint, along with higher vGRF asymmetry and trunk range of motion. Momentum and extension phases generated significant asymmetries at the knee between limbs of iTTA (p < 0.05).

Results support that iTTA rise from a chair with high joint asymmetry that might lead to disproportionate worn out of joints and secondary issues.