Award Date

5-15-2025

Degree Type

Doctoral Project

Degree Name

Doctor of Physical Therapy (DPT)

Department

Physical Therapy

First Committee Member

Jenny Kent

Second Committee Member

Daniel Young

Third Committee Member

Kai-Yu Ho

Number of Pages

35

Abstract

Background/ Purpose: There is limited understanding of how the sensory deficits associated with lower limb amputation (LLA) impact mobility during daily life. As a first step to developing this understanding, the aim of this study was to determine to what extent people with LLA can identify differences in commonly encountered walking surfaces beneath their feet. We hypothesized that people with LLA would demonstrate a poorer ability to discriminate between different surfaces than people without an amputation, and that discrimination ability would be surface characteristic-specific; discrimination would be poor for roughness discrimination due to the lack of plantar sensation in the prosthetic foot, but less affected for motility (movement) discrimination, which may be sensible via proximal proprioceptors.

Number of Subjects: 15 individuals with unilateral LLA (13M, 1F; 92.2±15.0 kg; 1.70m ± .094 m). 15 unimpaired controls (7M, 8F; 71.4 ± 18.0 kg; 1.66m ± 0.157 m).

Materials and methods: The testing apparatus consisted of two 1” high platforms at each end of a set of 7’ parallel bars. Two surface samples (2’ x 1’ x 1”) were placed between platforms, in parallel, such that one foot would contact each sample during stepping. Goggles and noise canceling headphones eliminated visual and auditory cues. The discrimination test included 4 surface materials; sandpaper, sand, rough tile and gravel, selected to test how differences in qualities of roughness (sandpaper-rough tile) and motility (sandpaper-sand; rough tile-gravel) varied between groups. Ceramic was maintained as a comparator for each trial, with the opposite side randomized. During each trial, participants stepped on the samples, and were asked to state whether the surfaces below their feet felt the “same” or “different”. Participants completed 80 trials. The percentage of correct responses for each of the sample comparisons was computed. Linear models were used to examine differences in discriminant ability between participants with LLA and controls.

Results: Participants with LLA demonstrated 17% lower accuracy compared to controls (p = .003). Discriminant ability was significantly impacted by surface type (p < .001) with Gravel (Control = 95.4%, LLA = 78.6%), Sand (Control = 86.2%, LLA = 67.4%), Rough Tile (Control = 90%, LLA = 52.7%), and Sandpaper (Control = 16.7%, LLA = 27.2%) varying in accuracy. Supporting our hypothesis, people with LLA had poorer discriminant ability when the surface was less motile (gravel versus rough tile, p = .04) compared to if the surface was less rough (gravel versus sand, p = .84).

Conclusions: People with LLA are less accurate at discriminating between different surfaces compared to people without amputation.

Clinical relevance: An inability to differentiate between surfaces underfoot may affect the ability to respond quickly and appropriately to different terrain demands, potentially leading to reductions in confidence and increases in falls. Assessment and training on such surfaces may improve balance confidence and reduce fall risk.

Keywords

Lower limb amputation (LLA); somatosensory; surface discrimination

Disciplines

Physical Therapy

File Format

pdf

File Size

1410 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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