Biomechanical Comparison of Flexor Digitorum Profundus Avulsion Repair

Abstract

Purpose Multiple repair techniques have been investigated for flexor digitorum profundus (FDP) tendon avulsions. The purpose of this study is to compare the biomechanical characteristics of a new fully threaded titanium suture anchor with previously examined fixation techniques. Methods Repair of FDP tendon avulsions was performed in 18 fresh-frozen cadavers using one of three implants: Nano Corkscrew FT 1.7 mm suture anchor (Group 1; Arthrex, Inc., Naples, FL; n = 6), Mitek Micro 1.3 mm suture anchor (Group 2; Mitek Surgical Products, Westwood, MA; n = 6), or pullout suture button fixation (Group 3; n = 6). Constructs were preloaded before testing load to failure. For each trial, elongation at 20 N and maximum load, mean load to failure, stiffness, and failure mechanism were recorded. Results Load to failure occurred in all trials. Mean load to failure was significantly greater for Group 1 (61.6 ± 18.9 N) compared to Group 2 (42.5 ± 4.2 N; p < 0.05) and Group 3 (41.6 N ± 8.0 N; p < 0.05). Stiffness was significantly greater in Groups 1 and 2 compared to Group 3 (6.9 ± 2.2 N/mm vs. 6.1 ± 0.8 N/mm vs. 3.1 N/mm ± 0.5 N/mm, respectively, p < 0.01). Mechanism of failure differed between the groups: Group 1 broke at the anchor in two trials and tore through the tendon in three trials, Group 2's suture universally broke at the anchor, and Group 3's trials mainly failed at the button. Conclusions The Nano Corkscrew anchor (Group 1) has a significantly higher load to failure when compared with the other techniques. The higher load to failure of the corkscrew anchor provides a secure method for flexor tendon repair in zone I. Clinical Relevance A fully threaded titanium suture anchor used for FDP tendon avulsion injuries is likely to withstand early active range of motion protocols.

Repair of flexor digitorum profundus avulsions including the palmar plate: a retrospective comparative study of 56 cases

“…(1992) forces up to 3.5 kgf (34 N) might be expected during unresisted active mobilization of the fingers, and strength of tendon repairs above 3.5 kgf could provide the option for active tendon loads. Although some other methods used for reconstruction of FDP ruptures or avulsions have shown greater loads to failure in ex vivo experiments, the pull-out suture technique demonstrates load to failure that is at least double the normal physiological loads exhibited in maximal active DIP joint flexion (Putnam and Adamany, 2019; Silva et al., 1998).…”

The Transosseous Internal Four Strand Technique: A New All-Inside Technique for Zone 1 Flexor Tendon Repairs

“…34,35 Nevertheless, from the biomechanical point of view, recent bone anchor systems seem to be superior to traditional repair methods. 12,36 In biomechanical testing, bone anchors revealed an UFL and a 2GF of up to 115 and 59 N, respectively, 12 while the highest UFL for pull-out sutures reported in the literature are 73.5 N. 37 Data about biomechanical properties of internal transosseous suture techniques however are scarce and the measured parameters are often not standardized. [37][38][39][40] In this biomechanical experiment, we were able to show that our modification of the TILT/mLT repair greatly strengthens the repair.…”

Hook Plate as a Treatment for Flexor Digitorum Profundus Avulsion Types II and III

“…20 However, external fixation techniques have been associated with a higher number of complications such as infections, skin irritation, rupture of sutures, and nail matrix alterations. 4,7 In light of the above, recent literature has proposed improved surgical approaches such as suture anchors with buried backup fixation with transosseus tunnels, 5,18 pullout sutures with wire cerclages, 9 suture anchors with miniscrew, 13,17 mini-fragment screws, 8 suture to volar plate, 15,19 or simple wire interosseous fixation. 16 Kang et al 10 performed a reinsertion with volar plates in 2003.…”