COLLAGEN FIBER SLIDING DURING LIGAMENT GROWTH AND CONTRACTURE

It is hypothesized that the sliding of collagen fibers past one anothe r plays an important role in changes of ligament length during growth or contracture. To explore this possibility, we used the fluorescent d ye dichlorotriazinyl fluorescein to stain collagen fibers perpendicula r to their orientation in a rat medial collateral ligament model. Grow th, contracture, and control models (with rats weighing 50-75 g in the first and 500-600 g in the latter two groups) were studied. In the co ntracture model, the medial collateral ligament was transected distall y. Marking sutures were used to verify the presence of growth or contr acture in each medial collateral ligament. Fluorescence photomicrograp hy after 2 weeks demonstrated stained collagen fibers protruding from either side of the original mark as one would expect, in either growth or contracture, if the fibers slid past one another and away from the ir initial location during changes in length. By measuring the initial and final widths of the growth and contracture model marks and correl ating them to controls that had minimal growth (rats grow throughout t heir life) and were free of contracture, we have provided evidence tha t collagen sliding plays a significant role in changes in ligament len gth.