Letter to the Editor: Combined oblique and vertical everting running stitch: Redefining the biomechanics of wound closure

Abstract

The combined oblique and vertical everting running suturing (COVER) technique, which uses a combination of oblique and vertical running everting closures, has been proposed as an alternative approach to close the wound in order to offer biomechanical stability with an appropriate biological healing environment. By employing an angled suture orientation with a vertical everting pattern, the COVER technique redistributes tensile forces throughout wound margins, providing a more even stress field, thereby enabling precise apposition of tissues at several anatomic levels. Biologically, this arrangement would induce dilution of local stress while maintaining continual microcirculatory flow, preventing inflammation, and allowing controlled deposition of collagen and epithelialization. Recent studies have reported clinical results that suggest a potential benefit from the COVER technique in terms of healing rates, cosmetic outcome, and complication rates compared with conventional suture techniques. Mechanistic and concept-driven analyses of biomechanical implications, biological outcomes of the COVER configuration, and its applications in wound management under high-tension or reconstructive situations are exemplified.

Key Words: Combined oblique and vertical everting running suturing technique; Wound closure; Mechanobiology; Tension modulation; Microcirculation; Regenerative medicine; Scar remodeling

Core Tip: The combined oblique and vertical everting running suture technique integrates principles of biomechanical force transmission with tissue-level biological responses to promote a dynamic and optimized wound healing process. By redistributing tensile forces along oblique and vertical vectors, this approach effectively reduces localized stress concentration while preserving microvascular perfusion at the wound margins. Such biomechanical optimization supports accurate tissue realignment, enhances healing efficiency, and facilitates favorable scar formation. Collectively, this coordinated strategy provides a mechanistically grounded and clinically adaptable pathway to improve functional and cosmetic outcomes in selected surgical settings.

TO THE EDITOR

Technical core and biological principles

The combined oblique and vertical everting running suturing (COVER)-suturing approach integrates a closure technique based on the coordinated application of oblique suture orientation and a vertical everting configuration. The primary aim of this approach is to achieve stable wound-edge eversion while preserving and enhancing microvascular perfusion in surrounding tissues. By generating bidirectional tension vectors, the technique reflects the interaction between mechanical stability, biological response, and aesthetic outcome within a structure-function framework of wound repair[1]. Some interesting findings regarding the accuracy and stability of tissue apposition using vertical mattress sutures were reported by Lee et al[2], who found that the distance between the near musculo-peritoneal insertion point and the skin edge is important. In the COVER procedure, the far-far and the near-near components are designed in a depth-wise configuration so as to facilitate reliable dermal fixation and controlled epidermal eversion. This combination imposes on the tissue an inverse trapezoidal stress distribution, which enlarges the dermal contact area in a way that marginal retraction and inversion can be avoided, thus enhancing wound-edge geometry due to decreased distortion toward closure when compared with conventional wound-edge stability models reported by Liu et al[3]. Most importantly, in the case of COVER, stress is taken up along those oblique suture paths. This alternating stress in vertical and oblique directions leads to a more homogeneous balance of mechanical loading, reduces the peaks of tensile concentration, and enhances the durability of closure[4]. This spatial reconfiguration efficiently turns a localized tensile stress into a distributed shear stress field, resulting in a decrease in regional ischemia and a reduction of the likelihood of stress-induced tissue necrosis[5].

Local over-tension has been shown to reduce microcirculation of the wounded tissue and to retard wound healing, and to result in poor scar formation. Liu et al[6] showed that when applied under high tension, the traditional vertical mattress sutures strangled the skin edges, reducing perfusion and causing poor scarring. The COVER technique, however, permits gradual tensioning and thus may preserve microvascular flow. This mechanical environment limits ischemia-induced fibroblast activation and attenuates the overexpression of profibrotic mediators such as transforming growth factor-β1 (TGF-β1). By altering this wound environment, myofibroblast differentiation is suppressed, and a natural repair process similar to normal tissue regeneration is initiated. These findings are supported by experimental evidence. Studies demonstrate that once the system is able to co-regulate tension and maintain perfusion, coordinated migration of the epithelium returns, as does the stratified epidermis[7]. Increased vascularity and angiogenesis are known to be critical for the successful healing of wounds[8]. In a similar vein, the COVER technique works as a beat-boosting modulator that promotes the secretion of growth factors which enhance perfusion, accelerate tissue repair, and favor improved scar morphology. At the molecular level, novel spatiotemporal models of caspase activity support finely tuned enzyme dynamics that would facilitate cellular adaptation under microenvironmental stress. Through the generation of a low-tension, well-perfused, and anti-inflammatory environment, the COVER technique may help to induce a regenerative pro-mechanical-molecular coupling mechanism[9]. The combined diagonal and vertical suture components illustrated in Figure 1 form a closure system that integrates mechanical stability with physiological preservation, resulting in durable wound-edge eversion, equilibrated stress distribution, and intact microvasculature.

Figure 1 Biomechanical and tissue healing advantages of the combined oblique and vertical everting running suturing technique. A conceptual representation of the biomechanical and tissue-healing benefits of the combined oblique and vertical everting running suturing technique. This diagram illustrates the functioning of the combined oblique and vertical everting running suturing technique through mechanical stability and biological repair. The alternating vertical and oblique sutures on the left create an inverted trapezoidal tension field. Vertical sutures allow for everted wound edges and deep dermal fixation, while oblique sutures redistribute shear forces, maintaining epidermal-dermal apposition and preventing edge collapse or strangulation. The balanced tension on the right maintains perfusion and oxygenation, optimizing microvascular flow and ensuring cooperation between perivascular fibroblasts and endothelial cells. The result is a setting with low tension and high perfusion, creating favorable conditions for various processes, including orderly collagen deposition, vigorous new blood vessel formation, and smooth, even scarring. COVER: Combined oblique and vertical everting running technique.

Technical innovation and mechanistic advantages

Polykandriotis et al[10] indicate that the patient needs individualized suturing treatment, because the patient’s body shape and wound condition are variable factors not only for the choice of suture but also for the stitch. In the present study, a technique was developed according to this principle, and it was demonstrated that an oblique vector system can incorporate the critical aspects of vertical mattress suturing necessary for optimal biomechanical performance.

This arrangement similarly leads to a more homogeneous distribution of stress at the wound edge and lower surface pressure[11]. Clinical case series by Sadiq et al[1] suggest that this would reduce the number of sutures used, the duration of suture placement, as well as postoperative pain and complication rates in patients presenting with multiple lacerations. These data underscore the importance of the mechanical environment in the regulation of tissue remodeling during wound healing. Negative psychological outcomes, including anxiety and depressive symptoms, as well as pain experience in the postoperative stage and the presence of complications, are positively linked[12]. By reducing wound irritation and preserving a steady mechanical environment, COVER may further indirectly promote psychological recovery from surgery.

The cosmetic performance gains importance in the treatment of wounds. Alam et al[13] demonstrated that early biophysical regulation of tissue mechanics affected both collagen deposition and, ultimately, scar remodeling. COVER has been recognised as a method with good to excellent Hollander scores in the majority of treated wounds, and is accepted because it provides satisfactory cosmetic results and structural stability. These findings show smooth scar relief, good colour match to the surrounding tissue, and adequate visual integration. Neutrophil recruitment and inflammatory signaling, accompanied by disrupted microvascular perfusion and tissue integration, have been recognized to result from high strain[14]. Stress concentration and inflammatory signaling are suppressed by the COVER technique, which facilitates the orderly migration of cells, angiogenesis, and tissue remodeling. Key procedural, mechanical, and clinical differences between the COVER technique and traditional suture applications, demonstrating its potential in low-tension closures and cosmetic repair[15-18] in Table 1.

Table 1 Comparative analysis between the combined oblique and vertical everting running suturing technique and conventional suturing methods.

Ref.	Suturing technique	Mechanical and tensile characteristics	Tissue repair and healing dynamics	Scar morphology and aesthetic outcome	Biological response and perfusion regulation
Chen et al[15], 2023	Simple interrupted suture	Tension concentrated between suture points; overall stress remains high with localized traction	Slower healing; prolonged inflammatory phase	Wider scar; occasional edge depression or fibrotic thickening	Local perfusion limited; mild ischemic tendency
Patil et al[16], 2025	Vertical mattress suture	Dual-depth tension distribution; effective stress dispersion across wound edges	Faster healing with superior tissue adhesion and integration	Flat, inconspicuous scars with high visual conformity	Reduced tension improves perfusion and regeneration
Liu et al[17], 2022	Horizontal mattress suture	Even lateral stress distribution; good resistance to distraction but limited deep coaptation	Stable but moderate healing rate	Fine scar with occasional superficial indentation	Superficial perfusion improved; deep microcirculation partially restored
Li et al[22], 2023	Subcuticular continuous suture	Longitudinal tension transmission reduces dermal stress concentration	Rapid healing with minimal inflammation	Fine, flat scar with minimal chromatic variation	Dermal and subdermal perfusion markedly enhanced; improved oxygenation
Liu et al[3], 2021	Buried dermal suture	Superficial dermal tension predominates; limited eversion of wound edges	Moderate healing; mild early delay under tension	Smooth scar; occasional mild depression or discoloration	Limited microvascular improvement; mild compression of dermal circulation
Su et al[18], 2023	Barbed suture technique	Automatic tension redistribution along incision; knotless design reduces localized stress	Rapid healing with minimal mechanical load	Narrow, well-integrated scar; occasional minor extrusion risk	Distributed stress supports microcirculation, though overtightening may restrict flow
Sadiq et al[1], 2025	COVER suturing technique	Dual-vector (vertical and oblique) tension forming an “inverted-trapezoid” stress field; uniform traction prevents edge collapse	Significantly accelerated healing; minimal inflammation; no delayed closure observed	Thin, smooth, and chromatically consistent scar	Reduced tension enhances dermal microcirculation and oxygenation, promoting angiogenesis and epithelial reconstruction

COVER: Combined oblique and vertical everting running technique.

Clinical significance and future perspectives

Biomechanically, the COVER technique is structurally sound and histologically compatible, allowing it to be used in a variety of clinical situations. Newer sutures and alternate techniques are available for high-tension areas, including around the face, periarticular areas, and across abdominal incisions; however, conventional suturing techniques often fail to adequately relieve mechanical stress. Prolonged tension leads to excessive collagen formation, activation of myofibroblasts, and activation of the TGF-β1 signaling pathway, which all contribute, in turn, to hypertrophic scarring and wound edge contraction[5]. Continuous tension relief techniques confer obvious benefits in such anatomically challenging areas[19]. By repositioning multi-directional tension vectors, the COVER design maintains mechanical equilibration in a state of low stress, resulting in fewer tension-related complications upon implantation.

The COVER technique is highly useful for reconstructive and cosmetic surgery when stable wound-edge eversion is required. Managed eversion allows collagen to be properly laid down and wounds to heal free of uneven pigmentation and contour anomalies as scars mature. Hence, the COVER concept might also be applicable to facial repair and aesthetic restoration as well as functional rehabilitation. Perfusion and infection control remain critical in the management of complex wounds, and are traditionally addressed through pharmacological adjuncts[20,21]. The COVER method provides similar perfusion and oxygenation through biomechanical modulation alone, with less dependence on adjunctive treatments, while achieving similar blood flow and tension control. This mechanical enhancement might be one reason for a reduced infection rate and improved healing. The technique is easy to learn and simple, provided the direction of the suture line and the structural pattern are understood. Clinical observations have also suggested that operative time is reduced compared with double-layer closure suturing; therefore, thereby improving the effectiveness of treatment. These features render the COVER approach relevant in various patient care settings, including resource-limited environments and emergency trauma care.

However, the mechanical characteristics and tissue-level dynamics of the COVER configuration remain incompletely understood. There is still a significant lack of quantitative visualization of stress dissipation and tissue response. Li et al[22] created a three-dimensional finite element model to investigate the stress distribution in soft tissue with varying thickness and elasticity under predetermined tensile conditions, and this model is useful for craniofacial suture-tissue interactions. Such modeling of COVER may provide a quantitative visualization of tension distribution and static stability by projecting this approach onto a specific geometry and loading configuration. Novel imaging techniques such as optical coherence tomography, angiography, and laser speckle contrast imaging enable objective measurement of microvascular perfusion and might be adopted to monitor the suturing process in real time[23,24]. Prospective multicenter, longitudinal clinical trials will need to confirm the reproducibility and applicability of the COVER method to various types of wounds in different patient groups.

OUTLOOK AND FUTURE DIRECTIONS

The COVER technique goes even further; it is based on biomechanics, but also includes tissue-level biological mechanisms and aims to achieve the best outcome of wound healing. The method changes the mechanical environment in such a way that, through minimization of tissue stress, transformation of wound edge geometry, and maintenance of hemodynamic perfusion, a neuro-mediated environment for physiological healing rather than mere apposition of edges is created. Microscopic and molecular analyses of physiological responses to the COVER arrangement should be further conducted in future studies. Finite element modeling and photoelastic studies can continue to investigate the stress distribution patterns at different suture angles and depths[25]. Based on the evidence from animal experiments, the dual role of COVER technology in regulating inflammatory responses can be systematically evaluated, characterized by its inhibitory effect on fibrosis and its promoting effect on angiogenesis. Against this backdrop, long-term assessment of key molecular markers, including TGF-β1, is crucial for elucidating potential cellular dynamics[26]. Combining spatial molecular imaging and transcriptomics may uncover novel contexts in which tensile-modulated microenvironments influence cellular migration, matrix remodeling, or signaling crosstalk[27].

Progress in the fields of biomaterials and smart suture devices could also help extend the range of clinical applicability of COVER. Recent advancements consist of antibacterial silk-derived nanocomposite sutures and smart “artificial muscle” sutures capable of sensing mechanical load and adjusting contraction according to tissue status[28,29]. Incorporating such technologies into the COVER setup might provide adaptable patient-specific wound closure tactics. In conclusion, extensive biomechanical evaluation and multicenter, longitudinal clinical validation studies are required to determine the place of the COVER procedure in evidence-based surgical applications.