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The human patellar tendon moment arm assessed in vivo using dual-energy X-ray absorptiometry

Erskine, RM and Morse, CI and Day, SH and Williams, AG and Onambele-Pearson, GL (2014) The human patellar tendon moment arm assessed in vivo using dual-energy X-ray absorptiometry. Journal of Biomechanics, 47 (6). pp. 1294-1298. ISSN 0021-9290

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Abstract

Accurate assessment of muscle-tendon forces in vivo requires knowledge of the muscle-tendon moment arm. Dual-energy X-ray absorptiometry (DXA) can produce 2D images suitable for visualising both tendon and bone, thereby potentially allowing the moment arm to be measured but there is currently no validated DXA method for this purpose. The aims of this study were (i) to compare in vivo measurements of the patellar tendon moment arm (d) assessed from 2D DXA and magnetic resonance (MR) images and (ii) to compare the reliability of the two methods. Twelve healthy adults (mean±SD: 31.4±9.5yr; 174.0±9.5cm; 76.2±16.6kg) underwent two DXA and two MR scans of the fully extended knee at rest. The tibiofemoral contact point (TFCP) was used as the centre of joint rotation in both techniques, and the d was defined as the perpendicular distance from the patellar tendon axis to the TFCP. The d was consistently longer when assessed via DXA compared to MRI (+3.79±1.25mm or +9.78±3.31%; P<0.001). The test-retest reliability of the DXA [CV=2.13%; ICC=0.94; ratio limits of agreement (RLA)=1.01 (*/÷1.07)] and MR [(CV=2.27%; ICC=0.96; RLA=1.00 (*/÷1.07)] methods was very high and comparable between techniques. Moreover, the RLA between the mean DXA and MRI d values [1.097 (*/÷1.061)] demonstrated very strong agreement between the two methods. In conclusion, highly reproducible d measurements can be determined from DXA imaging with the knee fully extended at rest. This has implications for the calculation of patellar tendon forces in vivo where MR equipment is not available. © 2014 Elsevier Ltd.

Item Type: Article
Uncontrolled Keywords: 0903 Biomedical Engineering, 1106 Human Movement And Sports Science, 0913 Mechanical Engineering
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Publisher: Elsevier
Date Deposited: 25 Feb 2016 15:56
Last Modified: 07 Sep 2017 06:22
DOI or Identification number: 10.1016/j.jbiomech.2014.02.016
URI: http://researchonline.ljmu.ac.uk/id/eprint/2991

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