# Hyperspectral Imaging Reveals High Water and Hemoglobin Content at Rest and Decreased Oxygen Levels After Physical Activity at the Residual Limb of Non‐Dysvascular Lower Limb Amputees

## TL;DR

This study uses hyperspectral imaging to show that residual limbs of amputees have lower oxygen levels after physical activity, which may contribute to skin breakdown and pain.

## Contribution

The study introduces localized microcirculation changes in residual limbs after exercise using hyperspectral imaging in non-dysvascular amputees.

## Key findings

- Residual limbs showed lower limb circumference and subcutaneous fat compared to sound limbs.
- Tissue oxygenation decreased significantly in the residual limb after walking, but not in the sound limb.
- NIRPI decreased after walking in both limbs at location F2.

## Abstract

Skin integrity is one factor determining residual limb health. Oxygen deficiency caused by energy consumption and/or mechanical stress is the most common reason for skin breakdown at the residual limb (RL), limiting physical activity and causing residual limb pain (RLP). This study aims to detect differences in microcirculation at rest (T1) and after walking for 6 min (T2) with a socket prosthesis at different zones at the residual limb (RL) and the corresponding areas at the sound limb (SL).

Amputation and RLs' demographics as limb circumference (LCF), subcutaneous fat thickness (SCFT) and microcirculatory parameters as tissue oxygenation saturation (StO2), near‐infrared perfusion index (NIRPI), tissue hemoglobin index (THI) and tissue water index (TWI) were visualized and analyzed at different zones of the SL and RL of ten non‐dysvascular major lower limb amputees at T1 and T2 using ((HIS), TIVITA Tissue Diaspective Vision, Germany).

LCF and SCFT were lower at the RL than at the SL. A significant reduction of NIRPI after walking was observed at location F2, affecting both limbs. StO2 decreased significantly from T1 to T2 only at the residual limb at AL, with no corresponding change in the sound limb.

These findings demonstrate localized exercise‐related reductions in oxygenation at the distal RL, whereas microcirculation of the SL remained unchanged. Underlying factors and a possible impact on the overall residual limb health need further investigation.