Knee Torque and Gait Performance in Veteran Amputees: Biomechanical Insights Into Intact Limb Injury Risk

New recovery pathways to improve and sustain strength and functional outcomes in the veteran amputee population are required to reduce the onset of comorbidities with aging. To date, no comprehensive study has quantified key gait parameters with clinically applied tests and measured lower limb strength in this cohort and their relationship to potential indicators of onset of musculoskeletal (MSK) injuries. This study fills this gap. ADVANCE Study cohorts of unilateral transtibial (UTT; n = 12) and unilateral transfemoral (UTF; n = 10) veteran amputees were matched to military able-bodied controls (n = 10). Participants were tested using 3D motion capture system and force plates permitting analysis of the spatial-temporal intact knee joint kinetic parameters during a 6-minute walking test. An isokinetic dynamometer measured peak knee extension/flexion isometric torque and Hamstring:Quadriceps (H:Q) ratio. UTT amputees displayed a H:Q torque ratio below recommended, an imbalance that may alter their gait functionality within their intact limb. The intact knee extension-flexion torques across the cohorts did not display significant differences, suggesting the extensive military rehabilitation outcomes remained successful 12.5 years post injury. Six-minute walk test (6MWT) analysis demonstrated a similar walking speed and total distance covered between controls and UTT amputees. However, significantly lower values were found for UTF amputees. Ground reaction forces during weight acceptance on the intact side showed no significant differences between cohorts. However, at mid-support and push-off both injured cohorts displayed significantly greater forces in the last 30 s of the 6MWT, indicating kinetic asymmetries. The literature suggests that such differences may indicate unhealthy knee joints. This biomechanical study suggests that the U.K. veteran population conserved exceptional strength levels in their intact limb. However, submaximal exercises representing activities of daily living revealed focus for improvement in amputee gait. This highlights that individualized rehabilitation protocols and tools concentrating on prolonging patient quality of life may delay the early onset of MSK comorbidities.