Title

Enhanced Tendon-To-Bone Repair through Adhesive Films

Abstract

Tendon-to-bone surgical repairs have unacceptably high failure rates, possibly due to their inability to recreate the load transfer mechanisms of the native enthesis. Instead of distributing load across a wide attachment footprint area, surgical repairs concentrate shear stress on a small number of suture anchor points. This motivates development of technologies that distribute shear stresses away from suture anchors and across the enthesis footprint. Here, we present predictions and proof-of-concept experiments showing that mechanically-optimized adhesive films can mimic the natural load transfer mechanisms of the healthy attachment and increase the load tolerance of a repair. Mechanical optimization, based upon a shear lag model corroborated by a finite element analysis, revealed that adhesives with relatively high strength and low stiffness can, theoretically, strengthen tendon-to-bone repairs by over 10-fold. Lap shear testing using tendon and bone planks validated the mechanical models for a range of adhesive stiffnesses and strengths. Ex vivo human supraspinatus repairs of cadaveric tissues using multipartite adhesives showed substantial increase in strength. Results suggest that adhesive-enhanced repair can improve repair strength, and motivate a search for optimal adhesives.

Statement of Significance:

Current surgical techniques for tendon-to-bone repair have unacceptably high failure rates, indicating that the initial repair strength is insufficient to prevent gapping or rupture. In the rotator cuff, repair techniques apply compression over the repair interface to achieve contact healing between tendon and bone, but transfer almost all force in shear across only a few points where sutures puncture the tendon. Therefore, we evaluated the ability of an adhesive film, implanted between tendon and bone, to enhance repair strength and minimize the likelihood of rupture. Mechanical models demonstrated that optimally designed adhesives would improve repair strength by over 10-fold. Experiments using idealized and clinically-relevant repairs validated these models. This work demonstrates an opportunity to dramatically improve tendon-to-bone repair strength using adhesive films with appropriate material properties.

Department(s)

Mechanical and Aerospace Engineering

Comments

This study was supported by the National Institutes of Health (NIH): U01 EB016422 (to ST and GMG), R01 AR062947 (to ST), and F30 AR069491 (to SWL). Additionally, this study was supported by translational research grants from Washington University Institute for Translational and Clinical Sciences and Musculoskeletal Research Center (P30 AR057235).

Keywords and Phrases

Adhesive agent; Article; Biomechanics; Bone remodeling; Cadaver; Controlled study; Ex vivo study; Finite element analysis; Human; Human tissue; Prediction; Priority journal; Proof of concept; Rigidity; Rotator cuff; Shear strength; Shear stress; Tendon reconstruction; Adhesive; Biomechanics; Film; Rotator cuff; Shear lag; Tendon-to-bone

International Standard Serial Number (ISSN)

1742-7061; 1878-7568

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2018 Acta Materialia Inc, All rights reserved.

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