A Comparison Between Ischial-Containment and Sub-Ischial Prosthetic Sockets to Determine Their Effects on Secondary Health Conditions

Unilateral Transfemoral Amputation

transfemoral amputation, prosthetic socket design, low back pain

Long-term above-knee prosthesis users are at an increased risk of developing secondary musculoskeletal conditions compared to the general able-bodied population. One secondary physical concern is low back pain (LBP), for which the development is not entirely understood, but in above-knee prosthesis users it is believed to relate to asymmetries and compensations that are typically demonstrated and required to stand and walk. Understanding spinal motion and compensations will enhance our knowledge of the factors contributing to LBP, and possibly lead to the development of new prosthetic and therapeutic interventions to prevent or alleviate LBP, thereby improving mobility and quality of life for prosthesis users.

The purpose of this study is to investigate and compare the effects of the standard ischial containment (IC) socket to a sub-ischial (SI) socket design on the spinal and pelvic motions and leg length (LLD) discrepancies of transfemoral prosthesis users. Data will be collected from 2 groups of transfemoral prosthesis users (15 SI socket wearers and 15 IC socket wearers) and a group of 15 able-bodied (AB) control participants. Gait and standing analyses will be conducted on each participant using a marker based motion capture system. Prosthesis users will wear their own conventional sockets for the gait and standing analyses. Kinematic and kinetic data will be analyzed for differences between the 2 groups of socket wearers and will also be compared to the control group. The specific aims and hypotheses of this project are: Aim 1: To measure dynamic leg length and kinematics of the pelvis and spinal segments in unilateral, transfemoral prosthesis users during gait. Quantitative motion analyses will be performed on two groups of 15 research participants with lower limb amputation using 2 different socket designs (IC and SI) walking over level ground at three self-selected walking speeds (normal, moderately fast, fastest). Data will be compared between socket type and to an AB control group. Hypothesis 1a-IC socket wearers will have a greater anterior pelvic tilt compared to SI socket wearers and AB controls, and they will exhibit considerably greater rotations of the pelvis and spinal segments during walking. Hypothesis 1b-The EMG activity of the lumbar erector spinae for SI socket users will better approximate the patterns of AB controls as compared to IC socket wearers. Hypothesis 1c-The dynamic LLD will be greater for IC socket users compared to SI socket wearers and AB controls. Aim 2: To measure pelvic orientation and static leg length in unilateral, transfemoral prosthesis users during standing. A multi-segment model of the spine and pelvis will be used to determine neutral spinal, pelvis, and prosthetic alignment during standing for the research and AB control participants. Hypothesis 2a-IC socket wearers will demonstrate greater anterior pelvic tilt during standing compared to SI socket wearers and control participants. Hypothesis 2b-The prosthetic and sound leg lengths for both prosthesis user groups will be within 1.0 cm of each other during standing. Aim 3: To estimate joint contact forces in the legs and lower back of unilateral, transfemoral prosthesis users and controls during gait. Computational musculoskeletal simulations will be used to comprehensively evaluate the data from Aim 1 to compare the lumbar joint loads between IC and SI socket wearers. Hypothesis 3-IC socket wearers will exhibit greater lumbar joint loads than SI socket wearers.

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