title: The influence of ultrasound measurement techniques on the age-related differences in Achilles tendon size.
abstract: Achilles tendon (AT) properties change with age, however the extent to which aging influences the size of the AT may be influenced by the measurement technique. The purpose of this study was to 1) examine the age-related differences in AT size using measures of cross-sectional area (CSA) and thickness, and 2) to determine the test-retest reliability and minimum difference (MD) values of these measures. The size of the AT was examined in 19 young (19.79 ± 2.3 years) and 18 older (69.4 ± 3.1 years) healthy men on two separate occasions using an ultrasonography. The CSA and thickness of the AT were determined by separate transverse and longitudinal scans on the right leg at the same distance from the medial malleolus, respectively. Prior to and after accounting for body mass, AT CSA was larger (P ≤ 0.01) in the older men (64.49 ± 13.87 mm(2)) when compared to the younger men (44.12 ± 16.04 mm(2)), however there were no differences in AT thickness between age groups (P=0.96). In addition, there was no systematic error (P>0.05) between testing days, and the intraclass correlation coefficients, standard error of measurement (expressed as a % of the mean), and MD values for CSA and thickness ranged from 0.80-0.98, 5.46-8.68%, and 5.65-7.94 mm(2) and 0.51-0.86 mm, respectively between both groups. These findings suggest that the reliability of the CSA and thickness measurements were similar, however, CSA was a more sensitive measure to detect the age-related changes of AT size.
authors.affiliation: Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, MD, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Tweedell
authors.affiliation: Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Electronic address: edryan@email.unc.edu.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Ryan
authors.affiliation: Quintiles, Inc., Durham, NC, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Scharville
authors.affiliation: Valencell, Inc., Raleigh, NC, USA.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Rosenberg
authors.affiliation: Human Performance Laboratory, Department Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Sobolewski
authors.affiliation: Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Craig R
authors.initials: CR
authors.lastname: Kleinberg
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging*; D000293:Adolescent; D000367:Age Factors; D000368:Aged; D000375:Aging; D059925:Anatomic Landmarks; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult
keywords: Aging; Cross-sectional area; Reliability; Thickness