Figure 3

Multiscale tendon properties are altered with dynamic loading during tendon healing. (a) Healing tendons were evaluated for multiscale properties (macro and micro-scale) following dynamic loading. (b) Similar to uninjured tendon, the change in equilibrium stress was decreased in healing tendons due to high magnitude long duration loading. (c) Multiphoton imaging was used to assess collagen organization (white), amount of F-actin (purple), and nuclear aspect ratio (red) and disorganization following dynamic loading at different stages of healing (scale bar = 20 µm). (d) Collagen disorganization was strain responsive with dynamic loading in uninjured tendons, but was not responsive in healing tendons. (e) The change in nuclear aspect ratio decreased following high magnitude dynamic loading in uninjured and week-6 post-injury groups, but increased in the week-2 post-injury healing groups. *Panels b,d: Data shown as mean ± SD. N = 7–11/group. Lines indicate significant differences. Symbols indicate significant differences (#) or trends ($) compared to quasi-static loading samples (0 cycles). *Panel e: Data shown as mean ± SEM. N = 119–1012 cells/group.