A biomechanical comparison of four extensor tendon repair techniques in zone IV.

BACKGROUND: This study was designed to evaluate the biomechanical parameters of four different suture techniques specifically designed for zone IV extensor tendon injuries: the double figure of eight, the double modified Kessler, the six-strand double-loop, and the modified Becker suturing techniques. Ease of repair, tendon shortening, strength to 1-mm gap, strength to 2-mm gap, ultimate strength, and mode of repair failure were evaluated.

METHODS: Twelve fresh-frozen cadaver hand-forearm units (48 fingers) were randomly assigned to the four suture repair treatments. The speed of tendon repair as performed by two matched-hand surgeons was recorded. Prerepair and postrepair tendon lengths were measured to document tendon shortening. The repair was stressed by linear distraction at 2.0 mm/minute using a servohydraulic frame. Video recordings of each distraction were independently reviewed for biomechanical parameters by three physician-observers in a double-blind setup. A one-way analysis of variance and t test analysis was performed.

RESULTS: Results show that the double figure-of-eight technique and the double modified Kessler were significantly (p < 0.05) easier to perform at 7 minutes 31 seconds and 7 minutes 58 seconds, respectively, than the other two techniques. Tendon shortening ranged from 1.9 to 2.4 mm. There was no statistically significant difference in tendon shortening among the four techniques. Strength to 1-mm gap was significantly higher with the modified Becker technique, with a mean 28.8 +/- 8.0 N. This was followed by the six-strand double-loop technique, with 21.0 +/- 6.6 N, the double modified Kessler at 17.7 +/- 4.5 N, and the figure-of-eight technique at 17.5 +/- 2.4 N. Strength to 2-mm gap was significantly (p < 0.05) greater for the modified Becker technique and the modified Kessler technique at 56.0 +/- 9.2 N and 48.6 +/- 12.6 N, respectively, as compared with the other two suture methods. The modified Becker technique showed the highest ultimate strength at maximal loading at 63.3 +/- 7.8 N, followed by the double modified Kessler technique with strength of 56.8 +/- 14.8 N. Both were significantly stronger than the other two techniques.

CONCLUSIONS: This study shows that the modified Becker suture technique, although not easily performed, proved to be the strongest repair, with a significantly greater resistance to 1-mm and 2-mm gap and the greatest ultimate strength on maximal loading.