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This Article Full Text Full Text (PDF) All Versions of this Article: 107/3/880    most recent 00291.2009v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Couppé, C. Articles by Magnusson, S. P. PubMed PubMed Citation Articles by Couppé, C. Articles by Magnusson, S. P.

Mechanical properties and collagen cross-linking of the patellar tendon in old and young men

¹Institute of Sports Medicine, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; ²Department of Physical Therapy, Bispebjerg Hospital, Copenhagen, Denmark; ³Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland; and ⁴The University of Southern Denmark, Odense, Denmark

Submitted 1 April 2009 ; accepted in final form 20 June 2009

Age-related loss in muscle mass and strength impairs daily life function in the elderly. However, it remains unknown whether tendon properties also deteriorate with age. Cross-linking of collagen molecules provides structural integrity to the tendon fibrils and has been shown to change with age in animals but has never been examined in humans in vivo. In this study, we examined the mechanical properties and pyridinoline and pentosidine cross-link and collagen concentrations of the patellar tendon in vivo in old (OM) and young men (YM). Seven OM (67 ± 3 years, 86 ± 10 kg) and 10 YM (27 ± 2 years, 81 ± 8 kg) with a similar physical activity level (OM 5 ± 6 h/wk, YM 5 ± 2 h/wk) were examined. MRI was used to assess whole tendon dimensions. Tendon mechanical properties were assessed with the use of simultaneous force and ultrasonographic measurements during ramped isometric contractions. Percutaneous tendon biopsies were taken and analyzed for hydroxylysyl pyridinoline (HP), lysyl pyridinoline (LP), pentosidine, and collagen concentrations. We found no significant differences in the dimensions or mechanical properties of the tendon between OM and YM. Collagen concentrations were lower in OM than in YM (0.49 ± 0.27 vs. 0.73 ± 0.14 mg/mg dry wt; P < 0.05). HP concentrations were higher in OM than in YM (898 ± 172 vs. 645 ± 183 mmol/mol; P < 0.05). LP concentrations were higher in OM than in YM (49 ± 38 vs. 16 ± 8 mmol/mol; P < 0.01), and pentosidine concentrations were higher in OM than in YM (73 ± 13 vs. 11 ± 2 mmol/mol; P < 0.01). These cross-sectional data raise the possibility that age may not appreciably influence the dimensions or mechanical properties of the human patellar tendon in vivo. Collagen concentration was reduced, whereas both enzymatic and nonenzymatic cross-linking of concentration was elevated in OM vs. in YM, which may be a mechanism to maintain the mechanical properties of tendon with aging.

tendon dimension; tendon mechanical properties; aging; collagen; hydroxylysyl pyridinoline; lysyl pyridinoline; advanced glycation end products