Peripheral quantitative computed tomography: measurement sensitivity in persons with and without spinal cord injury.
OBJECTIVE
To determine (1) the error attributable to external tibia-length measurements by using peripheral quantitative computed tomography (pQCT) and (2) the effect these errors have on scan location and tibia trabecular bone mineral density (BMD) after spinal cord injury (SCI).


METHODS
Blinded comparison and criterion standard in matched cohorts.


METHODS
Primary care university hospital.


METHODS
Eight able-bodied subjects underwent tibia length measurement. A separate cohort of 7 men with SCI and 7 able-bodied age-matched male controls underwent pQCT analysis.


METHODS
Not applicable.


METHODS
The projected worst-case tibia-length-measurement error translated into a pQCT slice placement error of +/-3 mm. We collected pQCT slices at the distal 4% tibia site, 3 mm proximal and 3 mm distal to that site, and then quantified BMD error attributable to slice placement.


RESULTS
Absolute BMD error was greater for able-bodied than for SCI subjects (5.87 mg/cm(3) vs 4.5 mg/cm(3)). However, the percentage error in BMD was larger for SCI than able-bodied subjects (4.56% vs 2.23%).


CONCLUSIONS
During cross-sectional studies of various populations, BMD differences up to 5% may be attributable to variation in limb-length-measurement error.
Shields
Richard K
RK
Graduate Program in Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, IA 52242-1190, USA. richard-shields@uiowa.edu
Dudley-Javoroski
Shauna
S
Boaldin
Kathryn M
KM
Corey
Trent A
TA
Fog
Daniel B
DB
Ruen
Jacquelyn M
JM
D000328:Adult; D000368:Aged; D015519:Bone Density; D015331:Cohort Studies; D005260:Female; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013977:Tibia / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed