Evaluation of Suture Elongation of Flexor Tendons using the Pulvertaft Method: a Biomechanical Study using Cadaveric Specimens

Background. Determining flexor tendon tension in Pulvertaft methods is challenging. The tendons are sutured slightly tightly in anticipation of a postoperative decrease in flexor tendon tension, but it is not possible to predict by how much the tension will decrease. The purpose of this study is to determine the flexor tendon stretch length after undergoing Pulvertaft repair using the cyclic loading test. Methods. We obtained flexor tendons from fresh-frozen cadavers. We performed the flexor tendon suture using the Pulvertaft method from three to six weaves. We performed the cyclic loading tests to calculate suture stretch length. Next, we performed a single loading test to measure the failure load and record the mode of failure. We compared suture stretch length, failure load, and failure mode between the numbers of suture weaves. Results. The stretched lengths of the woven tendons in the 3-, 4-, 5-, and 6-weave groups were 2.99 +/- 0.33 mm, 2.60 +/- 0.25 mm, 3.48 +/- 0.30 mm, and 3.04 +/- 0.21 mm in the cyclic loading test, respectively. The mean failure load values of the woven tendons were 115.8 +/- 8.9 N, 162.8 +/- 18.5 N, 226.4 +/- 24.7 N, 306.7 +/- 36.0 N, respectively, with a significant difference between the groups Conclusions. Our study suggests that the use of the Pulvertaft method results in a stretch length of the sutured tendon by approximately 3 mm during rehabilitation. By performing the procedure while considering the postoperative stretching effect, it can be expected that better results will be obtained.