title: Muscle Density and Bone Quality of the Distal Lower Extremity Among Individuals with Chronic Spinal Cord Injury.
abstract: BACKGROUND
  Understanding the related fates of muscle density and bone quality after chronic spinal cord injury (SCI) is an important initial step in determining endocrine-metabolic risk.
  
  
  OBJECTIVE
  To examine the associations between muscle density and indices of bone quality at the distal lower extremity of adults with chronic SCI.
  
  
  METHODS
  A secondary data analysis was conducted in 70 adults with chronic SCI (C2-T12; American Spinal Injury Association Impairment Scale [AIS] A-D; ≥2 years post injury). Muscle density and cross-sectional area (CSA) and bone quality indices (trabecular bone mineral density [TbBMD] at the distal tibia [4% site] and cortical thickness [CtTh], cortical area [CtAr], cortical BMD [CtBMD], and polar moment of inertia [PMI] at the tibial shaft [66% site]) were measured using peripheral quantitative computed tomography. Calf lower extremity motor score (cLEMS) was used as a clinical measure of muscle function. Multivariable linear regression analyses were performed to determine the strength of the muscle-bone associations after adjusting for confounding variables (sex, impairment severity [AIS A/B vs AIS C/D], duration of injury, and wheelchair use).
  
  
  RESULTS
  Muscle density was positively associated with TbBMD (b = 0.85 [0.04, 1.66]), CtTh (b = 0.02 [0.001, 0.034]), and CtBMD (b = 1.70 [0.71, 2.69]) (P < .05). Muscle CSA was most strongly associated with CtAr (b = 2.50 [0.12, 4.88]) and PMI (b = 731.8 [161.7, 1301.9]) (P < .05), whereas cLEMS was most strongly associated with TbBMD (b = 7.69 [4.63, 10.76]) (P < .001).
  
  
  CONCLUSIONS
  Muscle density and function were most strongly associated with TbBMD at the distal tibia in adults with chronic SCI, whereas muscle size was most strongly associated with bone size and geometry at the tibial shaft.
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Jenna C
authors.initials: JC
authors.lastname: Gibbs
authors.affiliation: Lyndhurst Centre, University Health Network-Toronto Rehabilitation Institute, Toronto, Ontario, Canada.
authors.forename: B Catharine
authors.initials: BC
authors.lastname: Craven
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.|Lyndhurst Centre, University Health Network-Toronto Rehabilitation Institute, Toronto, Ontario, Canada.
authors.forename: Cameron
authors.initials: C
authors.lastname: Moore
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Adachi
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.|Lyndhurst Centre, University Health Network-Toronto Rehabilitation Institute, Toronto, Ontario, Canada.|Schlegel Research Institute for Aging, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Lora M
authors.initials: LM
authors.lastname: Giangregorio
mesh_terms: D000328:Adult; D000368:Aged; D015519:Bone Density; D005260:Female; D006801:Humans; D007866:Leg; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000503:physiopathology; D010024:Osteoporosis / Q000209:etiology* / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000150:complications* / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D013977:Tibia / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult
keywords: bone mineral density; bone quality; muscle density; muscle size; osteoporosis; peripheral quantitative computed tomography; spinal cord injury