Development of a Surgically Optimized Graft Insertion Suture Technique to Accommodate a Tissue-Engineered TendonIn Vivo

Abstract

The traumatic rupture of tendons is a common clinical problem. Tendon repair is surgically challenging because the tendon often retracts, resulting in a gap between the torn end and its bony insertion. Tendon grafts are currently used to fill this deficit but are associated with potential complications relating to donor site morbidity and graft necrosis. We have developed a highly reproducible, rapid process technique to manufacture compressed cell-seeded type I collagen constructs to replace tendon grafts. However, the material properties of the engineered constructs are currently unsuitable to withstand complete load bearing in vivo. A modified suture technique has been developed to withstand physiological loading and off load the artificial construct while integration occurs. Lapine tendons were used ex vivo to test the strength of different suture techniques with different sizes of Prolene sutures and tissue-engineered collagen constructs in situ. The data were compared to standard modified Kessler suture using a standard tendon graft. Mechanical testing was carried out and a finite element analysis stress distribution model constructed using COMSOL 3.5 software. The break point for modified suture technique with a tissue-engineered scaffold was significantly higher (50.62 N) compared to a standard modified Kessler suture (12.49 N, p<0.05). Distributing suture tension further proximally and distally from the tendon ends increased the mechanical strength of the repairs. We now have ex vivo proof of concept that this suture technique is suitable for testing in vivo, and this will be the next stage of our research.

Engineering the migration and attachment behaviour of primary dermal fibroblasts

“…Numerous studies show that the structure of collagen in 3D engineered collagen‐based materials differs from that of native collagen. Moreover, manufacturing processes such as crosslinking (used for Integra but not Matriderm) can further affect the structure of collagen including the availability of adhesion motifs, with “gelatinisation” having been described as a possible result of crosslinking treatments (Sawadkar et al, ; Tzeranis et al, ; Yannas, Tzeranis, Harley, & So, ). Our results show that when RGD‐binding integrins are blocked, there is reduced attachment and migration of dermal fibroblasts in 3D collagen‐based matrices (more specifically Integra), suggesting that RGD‐binding integrins are used when interacting with these materials as RGD motifs become available during manufacturing.…”

“…Numerous studies show that the structure of collagen in 3D engineered collagen-based materials differs from that of native collagen. Moreover, manufacturing processes such as crosslinking (used for Integra but not Matriderm) can further affect the structure of collagen including the availability of adhesion motifs, with "gelatinisation" having been described as a possible result of crosslinking treatments (Sawadkar et al, 2013;Tzeranis et al, 2016;Yannas, Tzeranis, Harley, & So, 2010 scaffold matrix/2D substratum. Moreover, the RGD blocking levels will depend on the cell population as well as on the material surface/ matrix used and would have to be established and fine-tuned for each particular application.…”

Biomechanical evaluation of a novel suturing scheme for grafting load-bearing collagen scaffolds for rotator cuff repair

“…However, very few studies have evaluated the performance of the mechanical strength of a scaffold in the context of repairing a spanning defect. 14, 27, 43 . Tendon repair with scaffolds involves suturing, which constitutionally creates defects in the scaffold and makes the scaffold weaker and vulnerable to failure after repair.…”

“…There are very few studies where scaffolds act as a load-bearing unit and the strength of those scaffold repairs are inadequate 14, 27, 43 . Therefore, these aforementioned scaffolds need sutures which bridge the gap so as to bear the load.…”

Susceptibility tensor imaging and tractography of collagen fibrils in the articular cartilage

“…In its most basic setup, AFM is a characterization technique used to determine the surface topology of a variety of materials (41) and can specially be used to measure the collagen fibril orientation at high resolution (42,43). In this study, following MRI experiments, specimens were decalcified, paraffin-embedded, and sectioned serially into 5-mm-thick sections.…”