Name: a novel tenorrhaphy suture technique with tissue engineered collagen graft to repair large tendon defects
Uploaded: 2021-12-10T13:00:00
Description: Watch this Scientific Journal Video about A Novel Tenorrhaphy Suture Technique with Tissue Engineered Collagen Graft to Repair Large Tendon Defects at JoVE.com

The authors would like to acknowledge UCL for funding this project.

NOTE: Experiment design and ethical approval were obtained from UCL Institutional Review Board (IRB). All experiments were carried out as per regulation of Home Office and guidelines of Animals (scientific procedure) Act 1986 with revised legislation of European Directive 2010/63/EU (2013). Rabbits were inspected by a named veterinary surgeon (NVS) periodically and twice in a day by a named animal care and welfare officer (NACWO) (As per guidelines and regulations of Home office). They did not show any sign of pain until...

In this study, tissue engineered type I collagen grafts was chosen as a tendon graft because collagen is a natural polymer and used as a biomaterial for various tissue engineering applications27,28. Also, collagen constitutes 60% of the dry mass of tendon, out of which 95% is type 1 collagen 21,29,30,31,<sup class=...

Tendon rupture may occur due to extrinsic factors such as traumatic lacerations or excessive loading of the tendon. Due to the external tensile forces placed on a tendon repair, a gap inevitably forms with most tendon repair techniques. Currently, tendon defects/gaps are filled with auto-, allo-, xeno- or artificial grafts, but their availability is finite, and the donor site is a source of morbidity.
The tissue-engineered approach to fabricate tendon graft from a natural polymer such as collagen has the distinctive advantage of being biocompatible and can provide vital extracellular matrix (ECM) components that facilitate cell integration. However, due to a lack of fibrillar alignment, the mechanical properties of the engineered tendon (ET) are inferior to the native tendon. To increase mechanical properties of the weaker collagen, many methods have been used, such as physical cross-linking under vacuum, UV radiation, and dehydrothermal treatments1. Also, through chemical cross-linking with riboflavin, enzymatic and non-enzymatic methods increased collagen density and the Young&#39;s modulus of the collagen in vitro2,3. However, by adding cross-linking agents, biocompatibility of the collagen is compromised, as studies have shown a 33% alteration in mechanical properties and 40% loss of cell viability3,4,5. Gradual accruement of alignment and mechanical strength can be obtained through cyclic loading6; however, this can be efficiently acquired in vivo7.
For ET to integrate in vivo and acquire strength without the need for chemical alteration, one approach would be to use a stabilizing suture technique to hold the weaker construct in place. Most tendon repairs rely on the suture design to hold tendon ends together; hence modification of these existing techniques could provide a logical solution8,9.
Until the 1980s, 2-strand repairs were widely used, but recent surgical literature describes the use of 4 strands, 6 strands or even 8 strands in repair10,11. In 1985, Savage described 6-strand suture techniques with 6 anchor points, and it was significantly stronger than the Bunnell suture technique that uses 4 strands 12. Also, 8-strand repairs are 43% stronger than other strands in cadaver and in situ models, but these repairs are not widely practiced as it becomes technically difficult to reproduce the repairs accurately13,14,15,16. Therefore, a greater number of core suture strands relates to a proportional increase in biomechanical properties of the repaired tendon. However, there is a loss of cell viability around the suture points, and trauma from excessive suturing can be to the detriment of the tendon, which can compromise tendon healing17. Suture techniques should provide a strong geometric repair that is balanced and relatively inelastic to minimize tendon gapping after repair. In addition, the location of the suture and its knots have to be strategically placed in order for them not to interfere with gliding, blood supply and healing until accruement of adequate strength has been obtained10,18.
To establish feasibility to secure weaker ET graft or other graft material in between ruptured tendon, we have developed a novel suture technique that can offload the graft so that it can mature and gradually integrate into the host tissue in vivo.

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a novel tenorrhaphy suture technique with tissue engineered collagen graft to repair large tendon defects

Surgical management of large tendon defects with tendon grafts is challenging, as there are a finite number of sites where donors can be readily identified and used. Currently, this gap is filled with tendon auto-, allo-, xeno-, or artificial grafts, but clinical methods to secure them are not necessarily translatable to animals because of the scale. In order to evaluate new biomaterials or study a tendon graft made up of collagen type 1, we have developed a modified suture technique to help maintain the engineered tendon in alignment with the tendon ends. Mechanical properties of these grafts are inferior to the native tendon. To incorporate engineered tendon into clinically relevant models of loaded repair, a strategy was adopted to offload the tissue engineered tendon graft and allow for the maturation and integration of the engineered tendon in vivo until a mechanically sound neo-tendon was formed. We describe this technique using incorporation of the collagen type 1 tissue engineered tendon construct.

We have used collagen grafts fabricated from type I collagen, as this is the predominant protein found in the tendon. It constitutes almost 95% of total collagen in the tendon; hence, collagen has exhibited all ideal properties for mimicking tendon in vivo21,22.
In this study, the type I collagen used was extracted from rat tail tendon and dissolved in the aceti...

Watch this Scientific Journal Video about A Novel Tenorrhaphy Suture Technique with Tissue Engineered Collagen Graft to Repair Large Tendon Defects at JoVE.com

A Novel Tenorrhaphy Suture Technique with Tissue Engineered Collagen Graft to Repair Large Tendon Defects

In this paper, we present an in vitro and in situ protocol to repair a tendon gap of up to 1.5 cm by filling it with engineered collagen graft. This was performed by developing a modified suture technique to take the mechanical load until the graft matures into the host tissue.

Surgical management of large tendon defects with tendon grafts is challenging, as there are a finite number of sites where donors can be readily ...

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