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Comparative Study
. 2006 Oct;87(10):1376-81.
doi: 10.1016/j.apmr.2006.07.257.

Peripheral quantitative computed tomography: measurement sensitivity in persons with and without spinal cord injury

Richard K Shields  1 , Shauna Dudley-Javoroski, Kathryn M Boaldin, Trent A Corey, Daniel B Fog, Jacquelyn M Ruen
Affiliations
Comparative Study

Peripheral quantitative computed tomography: measurement sensitivity in persons with and without spinal cord injury

Richard K Shields et al. Arch Phys Med Rehabil. 2006 Oct.

Abstract

Objectives: 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).

Design: Blinded comparison and criterion standard in matched cohorts.

Setting: Primary care university hospital.

Participants: 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.

Interventions: Not applicable.

Main outcome measures: 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.

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Conflict of interest statement

No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.

Figures

Fig 1
Fig 1
Location of pQCT slices. (A) Scans were obtained at 4% of the distal tibia length, at 3mm distal to 4% (D), and at 3mm proximal to 4% (P). (B) Schematic detail of region surrounding the pQCT slices. Heavy lines indicate the center of each slice. Dashed lines denote the slice thickness (2.2mm).
Fig 2
Fig 2
(A) Mean tibia length ± SE for 7 able-bodied subjects measured by 4 raters over 2 trials. (B) Mean absolute error ± SE in tibia length and percent error in tibia length for 7 able-bodied subjects measured by 4 raters (trials 1 and 2 combined).
Fig 3
Fig 3
Representative examples of pQCT scans from the 4% tibia site in an SCI and an able-bodied subject. Note the extensive loss of trabecular lattice and the degree of muscular atrophy in the SCI limb.
Fig 4
Fig 4
pQCT BMD results. Dark gray bars are mean ± SE for the able-bodied subjects. Light gray bars are mean ± SE for the SCI subjects. (A) Trabecular BMD at the distal (D), 4%, and proximal (P) measurement sites. *Significant difference (P<.05) from the corresponding SCI slice. (B) Difference in BMD from the 4% slice for the distal (D) and proximal (P) sites. *Significant difference from the 4% BMD value (P<.05).
See this image and copyright information in PMC

References

    1. Shields RK. Fatigability, relaxation properties, and electromyo-graphic responses of the human paralyzed soleus muscle. J Neurophysiol. 1995;73:2195–206. - PubMed
    1. Shields RK, Chang YJ. The effects of fatigue on the torque-frequency curve of the human paralysed soleus muscle. J Electromyogr Kinesiol. 1997;7:3–13. - PubMed
    1. Shields RK. Muscular, skeletal, and neural adaptations following spinal cord injury. J Orthop Sports Phys Ther. 2002;32:65–74. - PMC - PubMed
    1. Frey Law LA, Shields RK. Predicting human chronically paralyzed muscle force: a comparison of three mathematical models. J Appl Physiol. 2006;100:1027–36. - PMC - PubMed
    1. Wilmet E, Ismail AA, Heilporn A, Welraeds D, Bergmann P. Longitudinal study of the bone mineral content and of soft tissue composition after spinal cord section. Paraplegia. 1995;33:674–7. - PubMed

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