The In Vivo Human Patellar Tendon Mechanical And Collagen-cross-link Properties In Old And Young Men

Abstract

Aging affects muscle mass and strength, which affects ADL performance, but it remains unknown if the tendon properties also deteriorate with aging. Cross-linking (x-link) of collagen molecules provides structural integrity to the fibrils in tendons, and it is known to change with age in animal models, but has never been examined in humans. PURPOSE: To examine the mechanical properties of the patellar tendon, in vivo, and x-link properties in elderly (OM) and young males (YM). METHODS: Seven OM (67±1yrs, 86±4 kg) and 11 YM (27±1yrs, 81±2 kg) with the same activity level (YM 5±2 hrs/wk, OM 6±1 hrs/wk) were included. MRI was used to assess the tendon structural properties.Patellar tendon mechanical properties were assessed using simultaneous force and ultrasonography samplings. Tendon biopsies were obtained and analyzed for x-link content: Collagen concentration (Coll), Hydroxylysyl-pyridinoline (HP), Lysyl-pyrodinoline (LP), Pentosidine (Pent). Results are reported as Mean±SEM. Collagen and Crosslinks propertiesTABLERESULTS: Tendon structural properties did not differ between OM and YM. Similarly, the tendon mechanical properties did not differ between OM and YM. Significantly different from YM. p<0.05. **p<0.01 CONCLUSION: These data show that the structural and mechanical properties of the human patellar tendon, in vivo, do not differ in OM and YM. At the same time, these are the first data on humans that show an age-related difference in tendon x-link properties to our knowledge. OM displayed lower collagen content, but greater pentosidine x-links compared to YM. This age related increase in pentosidine x-link may serve to maintain the mechanical properties with aging.