The Impact of Unilateral Lower Limb Amputation on Spinal Loads
Condition: Low Back Pain
MeSH terms: Low Back Pain
Study type: Observational

Summary: 
      The prevalence of low back pain among persons with unilateral lower limb amputation is
      significantly higher than the rate experienced by the general public. Chronic pain, including
      low back pain, limits functional independence and negatively impacts quality of life. As
      such, this project will investigate the role of a biomechanical casual pathway in the
      development of low back pain; to do this, the investigators will explore the relationship
      between the adopted neuromuscular patterns post-amputation to perform activities of daily
      living and the risk of developing spinal tissue damage.
    

Detailed description: 
      Despite the higher prevalence of low back pain (LBP) among persons with unilateral lower limb
      amputation (ULLA) compared to able-bodied individuals, relatively little is known about the
      fundamental mechanisms underlying this condition. This research represents a first step
      toward investigating lower back biomechanics using advanced computational modeling techniques
      to inform the future design of effective interventions for LBP. Specifically, the impact of
      trunk neuromuscular patterns adopted by persons with ULLA while performing activities of
      daily living on spinal loads and the risk of spinal tissue damage will be investigated. This
      will be achieved via secondary biomechanical analyses of a large set of high-quality
      kinematics data obtained from individuals with and without ULLA performing the following
      tasks: 1) walking at self-selected and controlled speeds, 2) sit-to-stand and stand-to-sit,
      and 3) stairs-up and stairs-down. The central hypothesis is that, compared to able-bodied
      individuals, trunk movement strategies adopted by persons with ULLA to cope with physical
      demands of common daily activities are associated with a complex pattern of internal muscle
      forces that result in larger loads on the spine and a higher probability for spinal tissue
      damage. Investigators' dataset draws from the Biomechanics Laboratory at Walter Reed National
      Military Medical Center (WRNMMC) which has unprecedented access to a large population of
      service members with ULLA. Using this unique database, investigators will implement their
      novel finite element modeling approach to estimate the internal muscle forces (i.e., adopted
      neuromuscular patterns) needed to perform daily physical activities on the basis of
      satisfying equilibrium and stability across the entire lumbar spine. Completion of this
      project will enable the investigators to determine differences in muscle recruitment, as well
      as the resultant effects on spinal loads and the risk of spinal tissue damage, between
      persons with and without ULLA. Hence, this pilot project is expected to establish the initial
      groundwork for future research involving the design of highly specific interventions aimed at
      trunk neuromuscular behaviors during post-amputation rehabilitation to lessen adverse effects
      on lower back biomechanics and the potential for LBP.
    

Intervention name(s): Activity of daily living
Intervention type(s): Other
Intervention description(s): walking, sitting-to-standing and standing-to-sitting, stairs ascending and descending
Observational model: Case-Control
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        This project involves secondary analyses of existing data and so will not include a subject
        recruitment process. Kinematics data collected at Walter Reed National Military Medical
        Center will be used for estimation of internal muscle forces and the resultant spinal loads
        and the probability of spinal tissue damage during several basic activities of daily living
        using a computational model of the lower back. Following an initial assessment, the
        investigators estimate the following available sample sizes for each activity of daily
        living: (transfemoral-TFA, transtibial-TTA, and Controls-CTL ) 1) level ground walking at
        four different speeds (nTFA= 57, nTTA= 53, nCTL= 32), 2) sitting-to-standing and
        standing-to-sitting (nTFA= 29, nTTA= 20, nCTL= 15), and 3) stair ascending and descending
        tasks (nTFA= 18, nTTA= 20, nCTL= 15).
      
Keywords: Spinal loads; Trunk muscle force; Computational modeling; Unilateral lower limb amputation