Prosthetic Alignment and Biomechanical Parameters in Transtibial Amputees due Landmines

Abstract

Abstract-The lack of objective information concerned to prostheses alignment is a common phenomenon in the area. When an inadequate angular location of the transtibial prosthetic socket appears, the biomechanical parameters in the joint and the location of the center of pressure (COP) in the amputees are affected; it also affects the amputee's comfort in the standing position. The aim of this study was to investigate the effect of transtibial prosthesis malalignment on biomechanical parameters. The effects of transtibial prosthesis alignment on biomechanical parameters were measured in terms of lower limb angles and the location of the center of pressure (COP) when the subject is in the static standing position. Amputees who were regularly attending in the Hospital Militar Central, Bogotá, Colombia, were invited to participate in this study. Seven subjects with transtibial amputation were recruited from the community.Seven insertion alignment conditions were measured in each of the 6 participants of the study, whereas participant seven (7) only six conditions were located, for a total number of 144 tests. The socket angle, the joint angles and the COP were recorded in computer files. The statistical analysis of the measurements showed variation intra and inter subjects. All angle perturbations revealed statistically significant differences on joint angles and the COP compared to the nominal alignment. The sagittal angle perturbations of the socket led to statistically significant changes in the antero-posterior direction of COP and the joint angles. Therefore, malalignment affected the lower limb angles and the location of the center of pressure (COP) in amputees with transtibial prostheses.

A systematic review of variables used to assess clinically acceptable alignment of unilateral transtibial amputees in the literature

“…4,17,18,22,29,31 The sagittal socket alignment was changed in one study. 28 The effect of sagittal and frontal prosthetic alignment adjustments were analyzed in 12 studies. 5 –7,9,10,16,20,30,32 –35 The transverse prosthetic foot rotation was changed in three studies.…”

“…Four studies reported the effects of prosthetic alignment adjustment on standing balance parameters. Luengas et al 28 reported that (±2°, 4° and 6°) sagittal socket adjustments changed the center of pressure (COP) location in prosthetic limb and the vertical component of COP showed significant correlation with socket position. The study also showed lower limb joint angle is a sensitive parameter to prosthetic alignment.…”

“…20,[28][29][30] The socket alignment was significantly correlated to vertical component of COP. 28 The sagittal prosthetic foot alignment could affect standing stability and change COP location. 20,29,30 The sagittal prosthetic alignment could also change sagittal angle of hip and knee joints, load line location and the muscle activity around knee joint in standing position.…”

“…The results of four studies contradicted to previous studies or result of same study. 4,16,28,36 For example, the prosthetic alignment adjustment led to significant increase of stance time and decrease of step length of sound limb at the same time. 36 Due to threats related to validity of included studies, confidence on results should regard cautiously.…”

“…4,7 The measurement tool calibration is specified at three study protocols. 28,35,38 Seven studies had statements about the quality of instrumentation. 4,5,28,31,32,33,38 Therefore, the internal validity, instrument reliability and comparison to gold standard were unclear.…”