Fat Infiltration and Pressure Ulcers in Wheelchair Users

Abstract

Individuals with spinal cord injuries (SCI) are at a higher risk for secondary complications, such as pressure ulcers and muscular atrophy. Fat infiltration commonly occurs in SCI individuals, and although it is prevalent, the infiltration process still remains largely unknown. Early pilot studies have found that fat infiltration is a risk factor to pressure ulcer development. Additionally, fat infiltration has found to decrease muscle quality and increase insulin resistance.

This study’s goal was to identify subject characteristics that are associated with fat infiltration and to determine if fat infiltration is in fact related to pressure ulcers.

Forty-four subjects, who primarily use wheelchairs for mobility, were recruited for this study, and FONAR Upright MRI scans were taken of their buttocks. An MRI analyzation software was utilized to segment the gluteus maximus and adipose of each subject and extract their MRI intensities. The effect size was used to quantify fat infiltration, and the quantity of fat infiltration and subject characteristics were analyzed by linear and binary logistic regression models.

With respect to the subject characteristics, a stepwise regression produced a model with two predictors of fat infiltration, years of wheelchair use (p=0.002) and spasticity (p=0.004). The model showed that subjects were likely to become fully fat infiltrated after around 25 years of wheelchair use, but spasms tended to give subjects an additional 25 years, buffering the fat infiltration rate. However, the relationship between fat infiltration and SCI-Adjusted BMI category (p=0.096) was weak. Contrary to previous research, there was no relationship between fat infiltration and pressure ulcer history (p=0.311). However, if individuals who were completely infiltrated (n=7) (i.e. ,the muscle is indistinguishable from the adipose) were excluded, individuals with pressure ulcer history had more fat infiltration (p=0.004).

Overall, this study was unable to find a direct correlation between fat infiltration and pressure ulcers. However, it speculated the idea that fully fat infiltrated subjects may have a different pathology of fat infiltration, and it presented a new potential protective factor, spasms, which may help healthcare professionals predict pressure ulcer occurrence and should be further researched to see the physiological effects.