Prosthetic gel liners are often prescribed for persons with lower-limb amputations to make the prosthetic socket more comfortable. However, their effects on residual limb pressures and gait characteristics have not been thoroughly explored. This study investigated the effects of gel liner thickness on peak socket pressures and gait patterns of persons with unilateral transtibial amputations. Pressure and quantitative gait data were acquired while subjects walked on liners of two different

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... m thicknesses. Fibular head peak pressures were reduced (p = 0.04) with the thicker liner by an average of 26 +/-21%, while the vertical ground reaction force (GRF) loading peak increased 3 +/-3% (p = 0.02). Most subjects perceived increased comfort within the prosthetic socket with the thicker liner, which may be associated with the reduced fibular head peak pressures. Additionally, while the thicker liner presumably increased comfort by providing a more compliant limb-socket interface, the higher compliance may have reduced force and vibration feedback to the residual limb and contributed to the larger vertical GRF loading peaks. We conclude that determining optimal gel liner thickness for a particular individual will require further investigations to better identify and understand the compromises that occur between user perception, residuallimb pressure distribution, and gait biomechanics. Abbreviations: ARL = average residual limb, BRL = bony residual limb, ESAR = energy-storage-and-return, GRF = ground reaction force, JBVAMC = Jesse Brown VA Medical Center, MARL = Motion Analysis Research Laboratory, PRL = padded residual limb, PTB = patellar-tendon-bearing, SACH = solidankle cushioned heel, SD = standard deviation, sDE = distal end of the tibia sensor, sDT = distal anterior tibia sensor, sFH = fibular head sensor, sMG = medial gastrocnemius sensor, sPT = patellar tendon sensor, TSB = total-surface-bearing, VA = Department of Veterans Affairs.