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.

Keywords

flexor - tendon - avulsion - repair - biomechanical

• References

• 1 Moiemen NS, Elliot D. Primary flexor tendon repair in zone 1. J Hand Surg [Br] 2000; 25 (01) 78-84
• 2 Huq S, George S, Boyce DE. Zone 1 flexor tendon injuries: a review of the current treatment options for acute injuries. J Plast Reconstr Aesthet Surg 2013; 66 (08) 1023-1031
• 3 Bidwai ASC, Feldberg L. The button-over-nail technique for zone I flexor tendon injuries. Hand Surg 2012; 17 (03) 365-369
• 4 Silva MJ, Hollstien SB, Brodt MD, Boyer MI, Tetro AM, Gelberman RH. Flexor digitorum profundus tendon-to-bone repair: an ex vivo biomechanical analysis of 3 pullout suture techniques. J Hand Surg Am 1998; 23 (01) 120-126
• 5 Lee SK, Fajardo M, Kardashian G, Klein J, Tsai P, Christoforou D. Repair of flexor digitorum profundus to distal phalanx: a biomechanical evaluation of four techniques. J Hand Surg Am 2011; 36 (10) 1604-1609
• 6 Halát G, Negrin L, Koch T. , et al. Biomechanical characteristics of suture anchor implants for flexor digitorum profundus repair. J Hand Surg Am 2014; 39 (02) 256-261
• 7 Brar R, Owen JR, Melikian R, Gaston RG, Wayne JS, Isaacs JE. Reattachment of flexor digitorum profundus avulsion: biomechanical performance of 3 techniques. J Hand Surg Am 2014; 39 (11) 2214-2219
• 8 Matsuzaki H, Zaegel MA, Gelberman RH, Silva MJ. Effect of suture material and bone quality on the mechanical properties of zone I flexor tendon-bone reattachment with bone anchors. J Hand Surg Am 2008; 33 (05) 709-717
• 9 Ruchelsman DE, Christoforou D, Wasserman B, Lee SK, Rettig ME. Avulsion injuries of the flexor digitorum profundus tendon. J Am Acad Orthop Surg 2011; 19 (03) 152-162
• 10 Kang HJ, Oh WT, Koh IH, Kim S, Choi YR. Factors influencing outcomes after ulnar nerve stability-based surgery for cubital tunnel syndrome: a prospective cohort study. Yonsei Med J 2016; 57 (02) 455-460
• 11 Bunnell S. Surgery of the Hand. 2nd ed. Philadelphia, PA: JB Lippincott Co; 1948
• 12 Chu JY, Chen T, Awad HA, Elfar J, Hammert WC. Comparison of an all-inside suture technique with traditional pull-out suture and suture anchor repair techniques for flexor digitorum profundus attachment to bone. J Hand Surg Am 2013; 38 (06) 1084-1090
• 13 McCallister WV, Ambrose HC, Katolik LI, Trumble TE. Comparison of pullout button versus suture anchor for zone I flexor tendon repair. J Hand Surg Am 2006; 31 (02) 246-251
• 14 Brustein M, Pellegrini J, Choueka J, Heminger H, Mass D. Bone suture anchors versus the pullout button for repair of distal profundus tendon injuries: a comparison of strength in human cadaveric hands. J Hand Surg Am 2001; 26 (03) 489-496
• 15 Murphy SF, McInerney NM, O'Shaughnessy M. Response to “Reattachment of Flexor Digitorum Profundus Avulsion: Biomechanical Performance of 3 Techniques”. J Hand Surg Am 2015; 40 (08) 1716
• 16 Hyatt AE, Lavery K, Mino C, Dhawan A. Suture anchor biomechanics after rotator cuff footprint decortication. Arthroscopy 2016; 32 (04) 544-550
• 17 Tingart MJ, Apreleva M, Zurakowski D, Warner JJ. Pullout strength of suture anchors used in rotator cuff repair. J Bone Joint Surg Am 2003; 85-A (11) 2190-2198
• 18 Barber FA, Herbert MA. Cyclic loading biomechanical analysis of the pullout strengths of rotator cuff and glenoid anchors: 2013 update. Arthroscopy 2013; 29 (05) 832-844
• 19 Seradge H. Elongation of the repair configuration following flexor tendon repair. J Hand Surg Am 1983; 8 (02) 182-185
• 20 Schuind F, Garcia-Elias M, Cooney III WP, An KN. Flexor tendon forces: in vivo measurements. J Hand Surg Am 1992; 17 (02) 291-298
• 21 Manske PR, Lesker PA. Avulsion of the ring finger flexor digitorum profundus tendon: an experimental study. Hand 1978; 10 (01) 52-55
• 22 Kessler I, Nissim F. Primary repair without immobilization of flexor tendon division within the digital sheath. An experimental and clinical study. Acta Orthop Scand 1969; 40 (05) 587-601