title: Not just quantity: gluteus maximus muscle characteristics in able-bodied and SCI individuals--implications for tissue viability.
abstract: OBJECTIVE
  Some individuals with spinal cord injury (SCI) remain pressure ulcer (PU) free whilst others experience a recurring cycle of tissue breakdown. Detailed analysis of gluteal muscle characteristics may provide insights to local tissue viability variability. The study hypothesis was that SCI individuals have altered muscle composition compared to able-bodied (AB).
  
  
  METHODS
  Ten AB and ten SCI received a supine pelvic CT scan, with contrast.
  
  
  METHODS
  Cross-sectional area (CSA) and overall muscle volume were derived using image analysis. Gluteal muscle tissue type was classified at the S2/S3 sacral vertebrae midpoint, the superior greater trochanters margin (GT) and the inferior ischial tuberosities margin (IT) using the linear transformation Hounsfield Unit scale.
  
  
  RESULTS
  SCI gluteal CSA was less than for AB throughout the muscle, with the greatest relative atrophy at the IT (48%). Average AB gluteal volume was nearly double SCI. Eight SCI had over 20% infiltrative adipose tissue, three with over 50%. SCI gluteal CSA and intramuscular fat infiltration were significantly negatively correlated (p < 0.05). SCI IT axial slices showed less lean muscle and higher intramuscular fat infiltration than more proximally (p < 0.05).
  
  
  CONCLUSIONS
  SCI gluteal muscle characteristics were indicative of impaired tissue viability. SCI disuse muscle atrophy was anticipated; the analytic approach further indicated that intramuscular atrophy was not uniform. SCI muscle composition showed increased proportions of both low density muscle and adipose tissue. CT scan with contrast is effective for gluteal muscle characterization. This assessment technique may contribute to determination of personalized risk for PU development and other secondary complications.
authors.affiliation: Advanced Platform Technology Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Wu
authors.forename: Kath M
authors.initials: KM
authors.lastname: Bogie
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D009133:Muscular Atrophy / Q000000981:diagnostic imaging* / Q000209:etiology; D009929:Organ Size; D011446:Prospective Studies; D013119:Spinal Cord Injuries / Q000150:complications / Q000000981:diagnostic imaging*; D014022:Tissue Survival; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: CT scanning; Image analysis; Muscle composition; Spinal cord injury; Tissue viability