Effects of 5-fluorouracil on flexor tendon repair

This study was performed to assess the effects of a single 5-minute exposure of 5-fluorouracil (5-FU) applied topically at the time of flexor tendon repair in an attempt to reduce postoperative adhesions. The flexor digitorum profundus tendon to the long and fourth toe of Leghorn chickens was lacerated and primarily repaired using a 2-strand technique. The repair site was then exposed to a single 5-minute application of 5-FU in concentrations of 5, 25, or 50 mg/mL. Legs were casted for 3 weeks. After death the tendon was examined for the work of flexion using a tensile testing machine and examined with light microscopy, scanning electron microscopy, and transmission electron microscopy for morphologic and histologic differences in adhesion formation. Forty-seven chickens were examined. Average work of flexion values were 0.12 J for normal tendon, 0.31 J for operative controls, 0.34 J for the 5 mg/mL group, 0.15 J for the 25 mg/mL group, and 0.19 J for the 50 mg/mL group. The work of flexion was significantly reduced in the 25 and 50 mg/mL groups compared with the operative controls (p =.008 and p =.03, respectively). Histologic sections as graded by a blinded pathologist revealed decreased adhesion formation in all the 5-FU-treated animals (p <.008). Histologic examination showed that the highest concentration of 5-FU was not as effective at reducing adhesions as the 25 mg/mL dose. This appeared to be due to increasing inflammatory changes seen around and within the tendons of the 50 mg/mL group. Overall, a single intraoperative application of 5-FU at concentrations of 25 mg/mL appears to be an effective mechanism for reducing postoperative flexor tendon adhesions.