Muscular Activation Differences during Daily Activities in a Unilateral Trans-Femoral Amputee

Abstract

Lower-limb amputees often exhibit an increased atrophy of remaining skeletal musculature as compared to the non-amputated side. This difference in lean mass may present variations in the contribution of physical effort between the affected and unaffected musculature. While most literature has focused mainly on microprocessor-controlled prosthetics, few investigations have examined mechanical (i.e., un-powered) prosthetics during daily activity tasks. PURPOSE: The purpose was to examine the electromyographical activity of the lower limb musculature of the amputated versus non-amputated side in a unilateral trans-femoral amputee. METHODS: The participant (n=1, age=26) performed four activities of daily living (i.e., sit-to-stand, 10-meter walk, and stair ascent and descent without support) with an above-knee mechanical prosthetic. The participant completed each task three times with 1-minute rest in between each trial. EMG was recorded, on both sides of the body, at the following sites and compared to a percentage of maximal voluntary contraction (%MVC): gluteus maximus (GM), gluteus medius (GMed), rectus femoris (RF), and biceps femoris (BF). Ratios (affected:unaffected) and percent differences between the affect and unaffected sides of the body were calculated. RESULTS: Results demonstrated large mean muscular activation differences of 34% for RF and 20% for GMed throughout overall movement patterns. Small mean activation differences were seen within the GM (2%) and BF (1%). The largest observed imbalance ratios for the sit-to-stand trials were in the RF (1:18) and GM (4:1). For the 10-meter walk, the largest differences were seen in the GM (3:1) and GMed (4.5:1). During the stair ascent without support, only the RF and GMed showed large imbalances between limbs (i.e., 1:3.5 and 3:1, respectively). Lastly, for the stair descent, the GM (4:1) and GMed (2:1) demonstrated a large imbalance; while BF and RF exhibited small differences. CONCLUSIONS: Results indicate that performing daily tasks for amputees may provide large imbalances in muscular effort between limbs. While some imbalances (increased motor unit recruitment) favored the unaffected limb, the affected limb did display increased recruitment in the gluteal musculature during walking, stair climbing, and sit-to-stand tasks.