Elastic suture thread
Fio de sutura elástico

INTRODUCTION

A wound is defined as a loss of skin coverage including skin, subcutaneous tissues, muscle, and bones. Wounds can be conceptualized as a “break in the continuity of a body structure” or a “rupture of normal tissue structures and functions.” They can be caused by internal or external trauma to the affected tissue, ranging from an acute and controlled injury to extensive aggression¹. Wounds are classified according to how they were produced and the degrees of contamination and tissue involvement². Wounds are classified as medium or large when primary closure is not possible. However, despite the lack of a single universally accepted definition, the term complex wound usually describes wounds that can anatomically involve multiple tissues, which often develop after devastating lesions and do not heal in a timely manner or at all. Trauma, the leading preventable cause of death, mainly affects economically active adults, creating a major social impact³.

Treating medium and large wounds is challenging because, without proper cleaning and care, they can lead to complications such as infections and poor healing. Optimal wound healing requires the removal of debris and necrotic tissue, bacterial load control, and appropriate closure. The ideal wound closure device should be easy and fast to use, be economical, cause no pain, and provide the best aesthetic result.

Preparation, the first step in medium and large wound resolution, involves cleaning and debridement for subsequent flap creation or grafting. However, surgical techniques using flaps or grafts have some disadvantages. Flaps can be cutaneous, fasciocutaneous, muscular, or myocutaneous, use tissues from adjacent or microsurgical/distant areas, and leave large scars and aesthetic deformities. On the other hand, skin grafts require donor areas and usually leave hypertrophic, retracted, and/or unaesthetic scars in the donor and recipient areas⁴.

Reconstructive plastic surgery is an important tool in the surgical treatment of complex wounds. It is based on two theories regarding its planning and execution: the reconstructive ladder and the reconstructive triangle. The ladder theory prioritizes the simplest solution for case resolution, such as grafting. If wound resolution does not occur, one proceeds to a more complex option, such as the use of local, expander, and free flaps. Modern reconstructive surgery techniques and the availability of more sophisticated equipment and materials have made the reconstructive triangle the most used model today. In this model, the chosen surgical technique is based on anticipating the quality of the final outcome. The chosen technique should preserve the shape and function of the area to be rebuilt regardless of complexity, provided that the patient is safe⁵.

Skin properties are extremely important in wound treatment. Elasticity is the quality that underlies the use of “elastic sutures” to close wounds over a short time span. This type of suture has been successfully used to close medium and large wounds⁶.

The elastic suture technique consists of stitching a rubber band on the wound margins. Tensioning the elastic band using an x-cross approximates the edges of the wound. This permanent and continuous tension approximates the edges, and total closure is achieved much faster than other closing techniques⁷ (Figures 1-3). To date, the material used as a rubber band is improvised by cutting surgical glove cuffs or using a rubber band for cash sterilized in ethylene oxide⁸.

Figure 1 - Preoperative period.

Figure 1 - Preoperative period.

Figure 2 - Immediate postoperative period.

Figure 2 - Immediate postoperative period.

Figure 3 - Result at 15 days postoperatively.

Figure 3 - Result at 15 days postoperatively.

This study aimed to develop a sterile needled surgical elastic suture according to the standards required by regulatory agencies. To achieve the desired objective, the elastic suture should have the strength and elasticity of the elastic material currently used in surgeries.

OBJECTIVE

To develop a double-needled elastic suture thread for the surgical closure of medium and large wounds.

METHODS

The study was analyzed and approved by the Research Ethics Committee of the Federal University of São Paulo (UNIFESP) under CAAE number 6291011217.

The elastic suture described in this study was filed at the Technological Innovation Center of the UNIFESP and evaluated for registration as a utility model at the National Institute of Industrial Property (Instituto Nacional de Propriedade Industrial [INPI]).

Suture prototype

The prototype begins with the production of a silicone rubber blanket that goes through several mixtures from which the operator collects samples to determine color and hardness using the shore durometer device⁹. This sample is placed in an extruder machine and the material gets the desired shape according to the matrix, in this case, a cylindrical cord¹⁰. The material passes through a heating tunnel with temperatures of 150-200 °C, where the silicone is vulcanized. Finally, the material is placed in a post-curing oven (200 °C/2 hours) to eliminate odors; after being treated with a catalyst, it becomes nontoxic. Subsequently, the cords are evaluated for size, hardness, and appearance¹¹.

The produced prototypes had diameters of 2.8 and 2.5 mm, similarly to the elastic materials, and 40, 50, and 60 shore density (Figure 4A). Manual, tactile, and visual tests favored the 50-shore density prototype, whose samples were sent to the Falcão Bauer Laboratory - Quality Control Technology Center - for elasticity, strength, and tension evaluations.

Figure 4 - A: Silicone molecule; B: Molecular formula of silicone.

Figure 4 - A: Silicone molecule; B: Molecular formula of silicone.

The laboratory tested five specimens (200-mm length) that were fixed one at a time to the test machine hooks and pulled at a constant speed of 50 mm/min until rupture. Maximum strength and elongation at rupture were recorded (Table 1).

Table 1 - Results of tests performed by Falcão Bauer laboratory evaluating elasticity, resistance and tension.

Test	Value found
	TB1	TB2	TB3	TB4	TB5	Mean
Maximum strength, kgf	5.05	4.95	4.55	4.60	4.40	4.71
Elongation at rupture, %	10001.33	816.52	705.16	773.99	891.51	837.70

TB: Test Body.

Table 1 - Results of tests performed by Falcão Bauer laboratory evaluating elasticity, resistance and tension.

A comparison with the elastic material normally used for elastic sutures showed that the length of the thread could be 45 cm, meeting the parameters already standardized by surgical suture companies. The double-needled elastic thread was produced with needle length, diameter, and type similar to those of standard suture threads (Figure 4B).

RESULTS

The Clarke, Modet & C° office selected five documents that matched the research objective to identify products that were similar to the elastic suture developed in this study. The identified products were classified by relevance according to the following scale: low (2), medium (2), and high (1).

Tables 1-5 summarize the information presented in the technical patent reports and compare the patented devices with the device developed in the present study in terms of applicability, material used, and usage.

Table 1 - Comparative 1.

Table 2 - Comparative 2.

Table 3 - Comparative 3.

Table 4 - Comparative 4.

Table 5 - Comparative 5.

The results of the tests at Falcão Bauer Laboratory evaluating the device’s elasticity, resistance, and tension are presented in Table 1. The data show that the elastic suture prototype presented in this study has a mean elastic capacity 8.3 times its original length, greater tensile strength than the elastic material currently used, and great elastic capacity (1001.33%) and tensile strength (Falcão Bauer Laboratory).

The analysis of the data presented in Table 1 comparing the prototype to currently used elastic materials show that, despite some similarities, the elasticity properties along the entire thread, diameter of 2.5 mm (increasing strength), and double needles make the prototype a useful model. The device developed in this study is called ElasticLine (Figures 6 and 7).

Figure 6 - Suture thread prototype.

Figure 6 - Suture thread prototype.

Figure 7 - Needle types.

Figure 7 - Needle types.

DISCUSSION

The present study describes the development of ElasticLine, a sterilizable elastic cylindrical monofilament thread prototype 2.5 mm in diameter when not tensioned created for elastic sutures. The ElasticLine is expected to be used in simple and fast elastic sutures using a product manufactured for this purpose that meets the requirements and standards outlined for medical products by the supervising bodies. The development of the ElasticLine is timely because, to date, plastic surgeons have improvised elastic sutures with cuffs cut out from surgical gloves or elastic rubber bands⁷.

The viscoelastic properties of the skin allow the use of devices that stretch it through constant traction and maintain the edges of large wounds in contact to enable closure without exacerbated tension. Several types of skin stretching devices have already been described, such as the four pins inserted by Kirschner around a wound in 1987. In addition, in 1995, Armstrong developed a mechanical device for attaching wound edges, while Narayanan used a metal cylinder fixed inside the wound for suture traction in 1995. These devices are uncomfortable and costly. In 2011, Ismavel¹⁶ sutured the edges of large wounds using glove cuffs. This technique was the inspiration for the present study of the development of a specific elastic suture thread called the ElasticLine.

The development of an elastic suture thread is necessary given the rigorous health surveillance of the use of appropriate products for each function and the need for a product like the currently used sutures. The ElasticLine enhances the elastic properties of the skin without causing dehiscence, which is very common with the use of inelastic sutures that promote high skin tension¹².

Silicone was the raw material chosen to produce the ElasticLine due to being easily available, being of low cost (approximately BRL 5.00/m), having high elastic capacity (1001.33%), and having high tensile strength. It is also nontoxic and sterilizable, recommended for surgical procedures according to the rules of regulatory agencies such as the National Health Surveillance Agency.

The inclusion of double needles will facilitate elastic suturing by x-crossing the thread. The other devices found in the patent search have different diameters and elasticity levels and do not have double needles, thereby establishing important differences between this utility model and the other devices.

It is increasingly important to search for practical and inexpensive solutions for medical treatments. The development of modern surgical devices is of paramount importance since easier procedures benefit surgeons and patients.

CONCLUSION

The ElasticLine is a double-needled elastic suture that was developed for the surgical closure of medium and large wounds.