Tissue loads applied by a novel medical device for closing large wounds

Abstract

Closure of large soft tissue defects following surgery or trauma as well as closure of large chronic wounds constitutes substantial but common reconstructive challenges. In such cases, an attempt to use conventional suturing will result in high-tension closure, therefore alternative external skin stretching systems were developed. These types of devices were meant to reduce local mechanical loads in the skin and the underlying tissues, taking advantage of the viscoelastic properties of the skin, especially mechanical creep, for primary wound closure. Studies have shown the clinical advantages of skin stretching systems, however, quantitative bioengineering models, demonstrating closure of large wounds, are lacking. Here we present finite element (FE) modeling of the TopClosure(®) tension relief system (TRS) and its biomechanical efficacy in three (real) wound cases, compared with the alternative of a conventional surgical suturing closure technique. Our simulations showed that peak effective stresses on the skin were at least an order of magnitude greater (and sometimes nearly 2 orders-of-magnitude greater) when tension sutures were used with respect to the corresponding TRS data. For the tension suture simulations, the tensile stress was in the range of 415-648 MPa and in the TRS simulations, it was 16-30 MPa. Based on the present computational FE modeling, the TRS reduces localized tissue deformations and stress concentrations in skin and underlying tissues while closing large wounds, compared to the deformations and stresses that are inflicted during the process of suturing. This substantial reduction of loads allows surgeons to better employ the viscoelastic properties of the skin for primary wound closure.

Keywords: Finite element modeling; Soft tissue; Tension relief system; Tension sutures.