Shear lag sutures: Improved suture repair through the use of adhesives

Abstract

Suture materials and surgical knot tying techniques have improved dramatically since their first use over five millennia ago. However, the approach remains limited by the ability of the suture to transfer load to tissue at suture anchor points. Here, we predict that adhesive-coated sutures can improve mechanical load transfer beyond the range of performance of existing suture methods, thereby strengthening repairs and decreasing the risk of failure. The mechanical properties of suitable adhesives were identified using a shear lag model. Examination of the design space for an optimal adhesive demonstrated requirements for strong adhesion and low stiffness to maximize the strength of the adhesive-coated suture repair construct. To experimentally assess the model, we evaluated single strands of sutures coated with highly flexible cyanoacrylates (Loctite 4903 and 4902), cyanoacrylate (Loctite QuickTite Instant Adhesive Gel), rubber cement, rubber/gasket adhesive (1300 Scotch-Weld Neoprene High Performance Rubber & Gasket Adhesive), an albumin-glutaraldehyde adhesive (BioGlue), or poly(dopamine). As a clinically relevant proof-of-concept, cyanoacrylate-coated sutures were then used to perform a clinically relevant flexor digitorum tendon repair in cadaver tissue. The repair performed with adhesive-coated suture had significantly higher strength compared to the standard repair without adhesive. Notably, cyanoacrylate provides strong adhesion with high stiffness and brittle behavior, and is therefore not an ideal adhesive for enhancing suture repair. Nevertheless, the improvement in repair properties in a clinically relevant setting, even using a non-ideal adhesive, demonstrates the potential for the proposed approach to improve outcomes for treatments requiring suture fixation. Further study is necessary to develop a strongly adherent, compliant adhesive within the optimal design space described by the model.

Effect of connective tissue growth factor delivered via porous sutures on the proliferative stage of intrasynovial tendon repair

“…A similar mechanical principle has been previously described for improved repairs using adhesive coatings on sutures. 24 …”

“…Flexor digitorum profundus (FDP) tendons were sharply transected in Zone II and repaired with unmodified or porous 4–0 Supramid core sutures using an 8-stranded Winters-Gelberman technique followed by a 5–0 proline running epitenon suture, as described previously ( n = 10 for porous sutures and n = 11 for unmodified sutures). 3,24 RHG performed the ex vivo repairs with porous sutures and SY performed the ex vivo control repairs with unmodified sutures using the same technique. Following clinical-style repairs, cadaver FDP tendons were biomechanically evaluated as described previously.…”

“…Following clinical-style repairs, cadaver FDP tendons were biomechanically evaluated as described previously. 24–26 After preconditioning, samples were pulled in uniaxial tension using a material testing machine (5866; Instron Corp., Norwood, MA) at 0.3 mm/s until failure and strain was tracked optically. 24,26 From the force-elongation curves, maximum load and load required to create a 2 mm gap in the repair (a clinically relevant measure of repair strength 9 ) were determined.…”

“…24–26 After preconditioning, samples were pulled in uniaxial tension using a material testing machine (5866; Instron Corp., Norwood, MA) at 0.3 mm/s until failure and strain was tracked optically. 24,26 From the force-elongation curves, maximum load and load required to create a 2 mm gap in the repair (a clinically relevant measure of repair strength 9 ) were determined. From the force-strain curves, rigidity (slope of the linear region), strain at 20 N force (approximating strains at physiologically relevant load levels 27,28 ), and a modified version of resilience (area under the curve until yield) were determined.…”

Cell and Biologic-Based Treatment of Flexor Tendon Injuries

“…Mechanically optimized adhesive coatings have potential to improve repair strength by several fold. 42 Experimental crosslinking agents coating sutures, including 1-ethyl-3-(3-dimethylaminopropyl) carbo-diimide hydrochloride (EDC) and cyanoacrylate, also increase suture-tendon interactions and crosslink the tendon tissue immediately adjacent to the suture. 43,44 These mechanical approaches offer an opportunity to improve repair strength, but do not inherently decrease adhesions or enhance the healing process.…”