Effect of suture material on gap formation and failure in type 1 FDP avulsion repairs in a cadaver model

Background An in vitro cyclical testing simulating a passive mobilisation protocol was used to compare repair of flexor digitorum profundus tendon with modified-Bunnell two-strand pullout technique using a monofilament (Prolene), braided polyester (Ethibond) and a synthetic polyfilament ensheathed by caprolactan (Supramid) sutures. Methods Eighteen fresh-frozen cadaveric fingers were randomly divided into three repair groups (n = 6); modified-Bunnell technique with 3/0 Prolene, Ethibond or Supramid. After repair, specimens were cyclically loaded from 2 to 15 N at 5 N/s, for a total of 500 cycles. Gap formation at the tendon–bone interface was assessed every 100 cycles. Samples were tested to failure at the completion of 500 cycles. Findings All sutures held in all specimens during cyclic testing. The gap formation after 500 cycles was greatest with Prolene suture (6.8 mm, SD 1.2) followed by Supramid suture (4.0 mm, SD 1.1) and Ethibond suture (1.7 mm, SD 1.7) (P < 0.05). Repairs with Supramid displayed higher failure load (52.7 N, SD 5.5) as compared to Prolene (37.6 N, SD 4.7) (P = 0.001) but not compared to Ethibond (44.9 N, SD 7.1). The failure loads between Prolene and Ethibond did not differ (P = 0.130). Interpretation Gap formation with Ethibond was significantly lower compared to Supramid and Prolene. The four strand nature of the Supramid repair was superior to Prolene but did not differ compared to Ethibond with respect to failure load. Prolene is the least favourable suture when considering gap formation and failure load, while Ethibond is the most favourable.