The early surface cell response to flexor tendon injury

Purpose: The migratory response of surface fibroblasts to flexor tendon injury was studied by their selective labeling with a vital dye. Method: The surfaces of 30 rat deep flexor tendons were bathed in 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine percholate (Dil), a vital dye for 5 minutes. The residual dye was removed by thorough irrigation. A partial tenotomy was made in the stained section by cutting out a central window. Semiquantitative cell counts and position of stained fibroblasts were noted by examination under flourescent light at 0, 1 3, 5, and 7 days. Results: The surface fibroblasts readily took up the vital dye at day 0. By day 1 dyed cells had moved into the cut. By day 3 they had migrated laterally into the core substance of the tendon. Core dyed cell counts at days 1, 3, 5, and 7 were significantly different compared with day 0 core dyed cell counts. Conclusions: This cell migration from the surface of the cut to the tendon core is likely to be vital in the early stages of tendon healing. Copyright (C) 2003 by the American Society for Surgery of the Hand.