Correlation between change in muscle excursion and collagen
The objectives of the present study were to compare changes in muscle excursion, total collagen, and collagen subtypes after tenotomy over time and after delayed tendon repair.

Passive muscle excursion decreased sequentially over time after tenotomy. Meanwhile, total collagen increased over time. These changes were significant after 4 weeks of injury. Type I collagen significantly increased, type III collagen significantly decreased, and type IV collagen had no significant change over time. Passive muscle excursion was negatively correlated with total collagen and type I collagen after tenotomy at each time point after tenotomy (p?<?0.05). After tendon repair, increases in total collagen content after tenotomy were not reversed, despite early repairs at 1 and 2 weeks after tenotomy.