Tissue Rearrangements

The z-plasty is a highly versatile standard technique of reconstructive burn surgery. Variations of the classic z-plasty with limbs of equal length at 60° angles can accommodate specific reconstruction needs. Opposing z-plasties can be used when available tissue is limited; series of z-plasties can be linked to elongate tissue over a longer distance with smaller individual incisions, and a z-plasty with varying limb angles and lengths can provide tissue coverage in areas with special distributions of scarred and normal skin.

Key points

  • The z-plasty is a highly versatile standard technique of reconstructive burn surgery.

  • The z-plasty can elongate tissue along a scar or contracture, narrow a scar in its transverse direction, rearrange the direction of a scar along relaxed skin tension lines, disperse and camouflage scar tissue in favor of cosmesis, and release tension, which ultimately reduces inflammation and hypertrophic scarring.

Introduction

The z-plasty could be considered one of the oldest tricks in every book of plastic and reconstructive surgery. Its versatility and universal applicability have placed it at the center of various publications over several centuries. Fricke and Horner described single transpositional flaps as early predecessors of the z-plasty as early as 1829. While surgeons such as Serre and Denonvilliers further improved the geometry of the technique and were using it for the correction of facial deformities and lower lid ectropion in the mid 1800s, the earliest publication of what is considered the standard contemporary z-plasty with equal limb dimensions and angles is attributed to French surgeons Berger and Bonset in 1904. The early 1900s saw a series of articles by Mc Curdy, who first coined the term in use today and introduced the technique to the correction of burn scars. In 1946’s first volume and second article in Plastic and Reconstructive Surgery , Davis evaluated and summarized the z-plasty and its variations as indispensable and versatile techniques. Since then, innumerable variations of the basic surgical concept and new potential applications have been published throughout the century by surgical pioneers such as Morestin, Davis, Limberg, and others.

To think of the z-plasty solely as workhorse of plastic and reconstructive surgery falls short of its actual impact on virtually all surgical specialties:

  • General surgeons have shown it to be useful in the treatment of sinus pilonidalis.

  • Oralmaxillofacial surgery uses it regularly in cleft palate repair.

  • Neurosurgeons have treated myelomeningoceles similar to how orthopedic surgeons ameliorated patellar compression syndrome with a variation of the z-plasty

  • Aesthetic surgeons improve the appearance of both genital and facial labia with this technique.

Introduction

The z-plasty could be considered one of the oldest tricks in every book of plastic and reconstructive surgery. Its versatility and universal applicability have placed it at the center of various publications over several centuries. Fricke and Horner described single transpositional flaps as early predecessors of the z-plasty as early as 1829. While surgeons such as Serre and Denonvilliers further improved the geometry of the technique and were using it for the correction of facial deformities and lower lid ectropion in the mid 1800s, the earliest publication of what is considered the standard contemporary z-plasty with equal limb dimensions and angles is attributed to French surgeons Berger and Bonset in 1904. The early 1900s saw a series of articles by Mc Curdy, who first coined the term in use today and introduced the technique to the correction of burn scars. In 1946’s first volume and second article in Plastic and Reconstructive Surgery , Davis evaluated and summarized the z-plasty and its variations as indispensable and versatile techniques. Since then, innumerable variations of the basic surgical concept and new potential applications have been published throughout the century by surgical pioneers such as Morestin, Davis, Limberg, and others.

To think of the z-plasty solely as workhorse of plastic and reconstructive surgery falls short of its actual impact on virtually all surgical specialties:

  • General surgeons have shown it to be useful in the treatment of sinus pilonidalis.

  • Oralmaxillofacial surgery uses it regularly in cleft palate repair.

  • Neurosurgeons have treated myelomeningoceles similar to how orthopedic surgeons ameliorated patellar compression syndrome with a variation of the z-plasty

  • Aesthetic surgeons improve the appearance of both genital and facial labia with this technique.

Principles

The basic idea of the z-plasty was best described by Limberg, who highlighted the flap’s simultaneous rotational and advancement properties and deducted its versatility from this unique combination. The main objectives of the z-plasty are

  • 1.

    Elongate tissue, usually along a scar or contracture, to release tension and enable mobility

  • 2.

    Narrow a scar in its transverse direction

  • 3.

    Rearrange the direction of a scar, favorably along pre-existing relaxed skin tension lines (RSTLs)

  • 4.

    Disperse scar tissue in favor of cosmesis

  • 5.

    Soften and thin scar tissue

Technique

Fig. 1 illustrates the concept of rotation and advancement of the classic z-plasty: a central vertical incision is placed in line with the long axis of the scar or line of tension. Two lateral limb incisions of the same length as the central incision are placed at its ends in a 60° angle. Next, the resulting triangular flaps are raised to the desired plane and rotated toward each other so that their tips fall into place in their respective opposite corners. The former shared sides of the triangles are now located toward flexible skin next to the limb incisions and a new, now horizontal, central limb is formed. The line of tension of the incised tissue is now perpendicular to its original direction. The costs for longitudinal elongation and elimination of 1 prominent scar are relative perpendicular tightening and 3 resulting smaller scars.

Fig. 1
Basic principle of the z-plasty: 2 opposing triangles of equal angles to a central incision along the line of tension are transposed. The result is a break up and lengthening of scar tissue and redirection of the scar in perpendicular direction.

Although this concept may appear simple and straightforward on the pages of a surgery textbook, its execution under real circumstances can prove to be challenging. Wanzel and colleagues demonstrated that the ability of surgery residents to properly execute a z-plasty (which they termed a “spatially complex surgical skill”) correlated with their performance in visual-spacial ability testing. Those who scored lower according to their visual-spacial ability required more supplementary training and feedback to achieve comparable operative results, demonstrating how challenging this seemingly simple procedure can be.

Elongation, Remodeling, and Reorientation

Tissue lengthening in the direction of the scar contracture after z-plasty is a function of the angles of the limbs toward their central incision. Mathematically, an increase in angle will result in increased central elongation ( Table 1 ). Likewise, elongation increases with the length of the central incision, but is proportionally dependent on sufficient adjoining tissue for transposition. However, these theoretic gains in length depend on the specific conditions encountered in each patient and scar. Davis describes that the best tension relief can be achieved when an isolated contracture band is surrounded by normal lax skin, which can be transposed, guaranteeing optimal flap perfusion. However, especially in the reconstructive treatment of burn contractures, this scenario is rare, and the common findings are transpositional flaps that are composed of scarred tissue themselves. Therefore, careful planning is paramount in order to produce the best possible outcome and avoid overestimation of the technique’s potential.

Table 1
Theoretic elongation of scar depending on symmetric angles of lateral z-plasty, limbs, and selected variations
Angle Between Lateral and Central Limbs (Degrees) Mathematical Gain in Length (%)
30 25
45 50
60 75
75 100
90 200
Variations
Two z-plasties in series 75
Double-opposing z-Plasty 75
Four-Flap-z-Plasty with 45° angles 100
Four-Flap-z-Plasty with 60° angles 150
Data from Thorne CH. Techniques and principles in plastic surgery in Grabb and Smith’s plastic surgery. 6th edition. Philadelphia: Lippincott Williams & Wilkins; 2007; and Hudson DA. Some thoughts on choosing a z-plasty: the z made simple. Plast Reconstr Surg 2000;106(3):665–71.

It is clinically evident that scar tissue shows a tendency to thin and soften after application of a z-plasty even if the scar is merely rearranged instead of excised. Aarabi and colleagues were able to demonstrate that mere mechanical scar tension alone can cause the development of hypertrophic scars in mice, leading to manifold increases in tissue volume, cell density, and dysregulated, decreased apoptosis. On the contrary, the redirection of tension on the tissue into the perpendicular direction causes mechanical stress relief. Histologically, a reorientation of collagen fibers resembling normal skin instead of hypertrophic scar as well as a replacement of abnormally sulfated mucopolysaccharides with normal acid mucopolysaccharides was demonstrated by Longacre and colleagues through immunohistochemical analysis of biopsies of scar tissue before and 2 weeks after z-plasty. He concluded that the surgical procedure had profound impact on a molecular level.

Reorienting a protuberant scar in a more favorable direction can have great consequences for its visible appearance. Burn scars over concave surfaces such as the neck, axilla, and popliteal area tend to hypertrophy, contract, and ultimately form a bowstring structure. Through correct design of the z-plasty in a way that the transverse limb after transposition lies in a natural concavity, functional and cosmetic outcome can be maximized. Furthermore, knowledge of the location and direction of naturally occurring folds and lines across the body add valuable information to the planning process of any incision, including a z-plasty. There are numerous classic concepts for designing optimal incision placement, such as Pinkus’ main folding lines, Kraissl’s antimuscular lines, and the RTSLs described by Borges. Newer approaches combine the data of these established concepts with the distribution of striae distensae, which form perpendicular to musculoskeletal lines of tension, to create more detailed composite diagrams that are also applicable to guide incision planning in younger patients. In general, a z-plasty executed in order to camouflage or disperse an existing scar should be designed so that the resulting transverse limbs after transposition lie within a naturally occurring skin line or fold. This, on the contrary, means that z-plasty should be avoided in cases in which the initial scar to be corrected is already located along the axis of a fold or line and the resulting transverse limb would be perpendicular and thus more conspicuous. Borges formulated the practical general rule that scars located 60° or more from an RTSL should be corrected with a z-plasty with 60° angled limbs; scars situated under 60° away from an RTSL should consequently be addressed with a z-plasty whose limbs fall on the RTSL.

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Nov 21, 2017 | Posted by in Dental Materials | Comments Off on Tissue Rearrangements
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