Soft-tissue defects are usually repaired by skin grafting [13], transferred free flaps [14], and skin expansion [15]. There are some problems with skin-grafting or free flap techniques [16], such as donor site damage [17], abnormal sensations [18], poor wear resistance of the grafted skin, bloated flaps [17], long learning curves for free or perforated flaps [19], and necrosis risks of the flap [20]. Skin soft-tissue expansion is a common surgical procedure to grow extra skin through controlled mechanical overstretching, which has been extensively applied in tissue repair and reconstruction in the field of plastic surgery for more than 30 years [15]. Skin expansion can be divided into internal expansion and external expansion. The aim of internal expansion is to detach the subcutaneous tissue and implant a dilator, resulting in the division of skin and other cells, and then “additional” skin can be acquired to repair the wound [21]. External expansion, which is also known as the skin stretching technique [10], pulls the normal skin on both sides of the wound edges to the center through external force and creates “additional” skin by linear loading with the help of skin viscoelasticity and extensibility to close wounds that are difficult to close conventionally [22]. Skin closure can be achieved with a skin dilator or a stretching device but is accompanied by complicated procedures and a high economic burden. The skin stretching device is essentially rigid; thus, it may produce unknowable tension in local tissue and usually causes necrosis, damage or avulsion of marginal wound tissue [10]. These methods are suitable for massive wounds with soft-tissue defects. For small- or medium-sized soft-tissue defects, skin stretch sutures with self-locking sliding Nice knots were first applied in this study. All wounds were gradually closed and successfully healed.
The characteristics of the skin are viscoelasticity, creep extensibility, and biological growth [23]. The viscoelasticity of skin is manifested in stress relaxation, which means that the intercellular spaces in the local skin tissues are opened and widened, while the skin tissue nearby shifts to a stretched area under pulling force [24]. The creep extensibility of skin is characterized by the rearrangement of collagen and elastic fibers after rapid expansion, and sometimes, type III collagen fibers and elastic fibers might rupture; therefore the skin is gradually elongated beyond its natural elongation and unable to ultimately return to its original position [25]. The skin can regenerate along the tension direction under the stimulation of stretching according to the tension-stress principle [26, 27]. On the basis of the viscoelasticity, creep extensibility, and biological growth of skin, the skin defects could be gradually closed with self-locking slide Nice knots in this study, a technique that was characterized by the simple procedure, strong tension, and gradual tightening [3]. The Nice knots could be gradually tightened once 2 days after the operation until the wound was closed. The mean time of closure of the soft-tissue defects was 10.69 ± 3.81 days without the need for more surgeries in this study.
However, to our knowledge, there have been no published studies on the effectiveness of Nice knots for soft-tissue defects. Our study was the first report about the application of Nice knots for wounds with soft-tissue defects. In our opinions, Nice knots can be used to close wounds caused by trauma, inflammation, tumor resection, bedsores, scar ulectomy, and the excision of skin grafts and flap donor sites. The contraindications of this method were patients with severe malnutrition, severe coagulation dysfunction, wounds without abundant blood supply, infectious wounds, and no insufficient normal skin around the defect. Nice knots were not used in areas of skin defects larger than 8.0 × 15.2 cm in this study. In the future, we will evaluate the clinical effects of applying Nice knots to massive wounds (larger than 8.0 × 15.2 cm).
The advantages of Nice Knot for soft-tissue defects were the simple procedure with few complications, the avoidance of damages to the donor sites, and the fact that skin maintained sensation and had more wear-resistance than flaps or grafted skin. The cost of this method was lower than that of skin expansion or skin stretching. The Nice knots could be applied to irregular wound areas. The disadvantages of this method are that it is not suitable for massive soft-tissue defects, there is pain when stretching the knots, and some tension scars formed after wound healing.
In our opinions, more attention must be paid to the following aspects. First, the Nice knots should be gradually tightened once every 2 days when swelling disappears and the blood supply. Second, Nice knots were not suitable for infectious or suspected infectious wounds; thorough debridement was necessary, and vacuum sealing drainage (VSD) was applied. Nice knots were applied to close the wounds after the granulation tissue in the wound was fresh. The closure speed was determined according to the blood supply of the skin and the patient’s pain tolerance. Finally, the removal time of the sutures should be prolonged to reduce tension scar formation.
There were some limitations in this study. First, this study was a retrospective clinical case analysis without a control group and was not a prospective study. Although we know that an included control group will make the study much stronger, it will be difficult for the close of size-mediate wound because of heterogeneous treatments. This study is just a new attempt that introduces a knotting method used widely for repairing rotator cuff tears in shoulder arthroscopy to close the skin wounds. In future, a randomized controlled trial will be performed to compare this new method with traditional methods for the closure of small- or medium-sized skin defects. A prospective study will be designed and applied in the future. Second, the sample size was not large enough because this was the first application of Nice knots on wounds with small- or medium-sized soft-tissue defects. Last, our clinical results are not being accurate because our follow-up time was not long enough.