EFFECT OF CYCLIC TENSION ON LACERATED FLEXOR TENDONS IN-VITRO

The effect of tension on tendon healing was evaluated in vitro using c yclic tension and no tension groups of chicken flexor digitorum profun dus tendons and histologic and immunohistologic techniques. A Vitrodyn e force-loading machine was used for application of cyclic tension on partially lacerated chicken flexor tendons in culture media. Laceratio n sites under cyclic tension after 14 days were covered by newly proli ferated fibroblasts, aligned in the direction of tension. This new gro wth was much thicker than that seen in the no tension group at the sam e time interval. Procollagen synthetic activity began at 3 days of cul ture in both groups. At 21 days, newly formed fibroblasts in the cycli c tension group were stained positive more strongly at the surface lay er than in the deeper layers. In the no tension group, the staining wa s primarily in the surface layer. Cyclic tension stimulated the intrin sic response of lacerated flexor tendons significantly more than no te nsion did by enhancing proliferation and migration of fibroblasts, as well as stimulating collagen synthesis.