title: A 3D mathematical model to predict spinal joint and hip joint force for trans-tibial amputees with different SACH foot pylon adjustments.
abstract: A solid-ankle cushioned heel (SACH) foot is a non-joint foot without natural ankle function. Trans-tibial amputees may occur toe scuffing in the late swing phase due to a lack of active dorsiflexion. To address this problem, clinical guidelines suggests shortening the pylon to produce a smooth gait. However, this causes a leg length discrepancy, induces asymmetry in the hip joint, and causes an overload of L5/S1 joint force. Therefore, this study aimed to investigate the influence of different prosthesis pylons on the hip joint and L5/S1 joint forces. Ten subjects were recruited using leg length for normalisation. Four different pylon reductions (0%, 1%, 2%, and 3%) were used for gait analysis. A Vicon system and force plates were used to collect kinematic data and ground reaction force, respectively. The software package MATLAB was used to create a mathematical model for evaluating the symmetry and force of the hip joint and the low back force of the L5/S1 joint. The model was validated by the correlation coefficient (CC=0.947) and root mean square (RMS=0.028 BW). The model estimated that the 1% group had a symmetrical hip joint force and a lower L5/S1 joint force in the vertical direction. This study indicates that a 1% pylon shortening on a SACH prosthesis is appropriate for a trans-tibial amputee.
authors.affiliation: Department of Physical Therapy and Assistive Technology, National Yang Ming University, Taipei, Taiwan, ROC.
authors.forename: Chung-huang
authors.initials: CH
authors.lastname: Yu
authors.affiliation: Rehabilitation Center, Taipei Veterans General Hospital, Taiwan, ROC.
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Hung
authors.affiliation: Department of Physical Therapy, Chang Gung University, Taoyuan, Taiwan, ROC.
authors.forename: Yang-Hua
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Department of Physical Therapy and Assistive Technology, National Yang Ming University, Taipei, Taiwan, ROC.
authors.forename: Guan-Xun
authors.initials: GX
authors.lastname: Chen
authors.affiliation: Department of Physical Therapy and Assistive Technology, National Yang Ming University, Taipei, Taiwan, ROC.
authors.forename: Shun-Hwa
authors.initials: SH
authors.lastname: Wei
authors.affiliation: Department of Biomedical Research, Mackay Memorial Hospital, Tamshui, Taipei County, Taiwan.
authors.forename: Chang-Hung
authors.initials: CH
authors.lastname: Huang
authors.affiliation: Department of Physical Therapy and Assistive Technology, National Yang Ming University, Taipei, Taiwan, ROC. Electronic address: cschen@ym.edu.tw.
authors.forename: Chen-Sheng
authors.initials: CS
authors.lastname: Chen
mesh_terms: D000674:Amputees / Q000534:rehabilitation*; D001186:Artificial Limbs; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait / Q000502:physiology*; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D013131:Spine / Q000502:physiology*; D013977:Tibia / Q000601:surgery
keywords: Gait analysis; Low back force; Mathematic model; SACH foot; Trans-tibial amputee