Layout of Skin Procedures

E. J. Mayeaux, Jr, MD, DABFP, FAAFP
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Subject: Layout of Skin Procedures

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Introduction

In determining the best possible layout for closure of a skin excision procedure or wound closure, several factors must be considered. Planning closure of a wound created by an excision procedure should be done before the skin is prepped or cut; it is necessary to understand how different excision procedures and flaps create new lines of tension or pull. Next, defining where the skin has the most laxity from which to pull will help in selecting closure types. Finally, by aligning the inherent stretch properties of the skin and the tension-creating properties of potential closures, adequate closure with the best cosmesis can be obtained. 

How Excision Procedures and Flaps Create New Lines of Tension or Pull

Whenever an opening is created in the skin, some of the remaining skin must be recruited from the area around the defect to primarily close it. As the surrounding skin is pulled, lines of tension are created parallel to the direction of pull. Fusiform (elliptical) excisions and each type of flap or plasty pulls skin from different directions, depending on how skin is recruited to close the skin defect. Generally, the tension is parallel to the direction of pull necessary to close the defect. Table 44-1 lists various closure options. The red arrows in the following figures show the direction of skin tissue generated by the closure. 

Determining Where the Skin Has the Most Laxity and Areas of Potential Recruitment

When preparing to do a skin excision procedure or to close an existing skin deficit, the ability of the skin to stretch and move to cover the defect and the cosmetic and functional results of that movement are the primary considerations. The most common problems are encountered in areas where the skin is closely attached or anchored to underlying or protruding structures. Examples include areas over the anterior tibia, around joints, and around protruding modified structures such as the nose, ears, or penis. The cosmetic implications of skin movement are particularly important near mobile, modified skin structures such as eyebrows, sideburns, vulva, and scrotum. Not only are there more limitations to undermining, but changing the shape, angle, or position of these structures can cause serious cosmetic problems. It is also very important around orifices such as the eyes, mouth, and vaginal introitus, because pulling tension in these areas may change their shape, causing cosmetic distress to the patient. 
 
Table 44-1.
After these problems are identified, the skin can be gently pushed with the surgeon’s fingers to determine if there is sufficient laxity to close the defect. The lines of least skin tension are natural lines of laxity in the skin (see Appendix B). Pushing the skin perpendicularly to the lines of least skin tension will reveal the most “give” in the skin. 

Aligning Excisions and Potential Closures to Get Adequate Closure and Best Cosmesis

The best cosmetic results are usually achieved when the final closure line (and therefore the scar) lies parallel to the lines of least skin tension. Start choosing possible closures by considering layouts that produce this result. When there is adequate skin to recruit for closure without tension, the fusiform excision is usually the easiest procedure to execute, because the final closure line is straight and easy to plan. Most providers will choose it as the default procedure when starting to lay out a procedure. Eliminate any closures that would pull skin tension from immobile areas or areas that would cause cosmetic problems (such as the eyebrow or mouth, because this would change the contours of these structures). 
Next consider where the skin must be recruited to close the defect. Can this area be safely undermined? Also, consider any significant underlying structures, such as arteries, veins, or nerve bundles, that must be avoided during excision or undermining for closure. 
Then consider in what directions the skin normally moves and stretches. Because movement stretches the skin, this makes sutures more likely to fail if the closure creates too much tension in the direction of normal skin movement. For example, skin on the back can move in almost any direction, making a V-to-Y-plasty (that pulls some tension from almost all directions) or a rotation flap (that can spread the tension over a wide area, thereby reducing the tension at any particular point) a better choice than a fusiform or advancement flap that pulls all the tension from one direction. 
Finally, consider the quality of the blood supply to the skin in the area, because some flaps can be done only in areas of good blood flow. 

Examples

For example, when considering a closure on the forehead, the final scar should follow the shape of the eyebrow (line of least skin tension). The skin should not be pulled from the inferior and superior directions, because that could permanently raise some or all of the brow. 
This would eliminate the fusiform excision. An O-to-Z-plasty or rotation flap would work, but it would not place most of the closure in line with the lines of least skin tension, would pull the skin at tangential angles, and would make longer scars. A double-V-to-Y-plasty or double advancement flap would put most of the final scar in the lines of least skin tension, not change the shape of the brow, and allow for good closure of the defect. Either of the latter two closures would work well. 
Fusiform excisions that line up with the lines of least skin tension will probably cause excessive vertical tension, thereby raising the brow and producing a larger scar. The scar will align with the lines of least skin tension. Not a good choice.  
Figure 1
Figure 1
The O-to-Z-plasty will probably raise the lateral part of the brow, and the scar will not align with the least tension skin lines, but will probably close with minimal tension. Adequate choice.  
Figure 2
Figure 2
A rotation flap would produce a curved scar that may displace existing wrinkles and heal with a larger scar. Not a good choice.  
Figure 3
Figure 3
An A-to-T-plasty would produce a large vertical scar that is perpendicular to the lines of least skin tension (and heal with a larger scar). Not a good choice.  
Figure 4
Figure 4
A V-to-Y-plasty pulls minimum tension from any particular direction and aligns well with the lines of least skin tension. It is less likely to alter the shape of the brow. Good choice.  
Figure 5
Figure 5
A double advancement flap aligns well with the lines of least skin tension and has essentially no risk of altering the brow. Good choice.  
Figure 6
Figure 6
Similarly, in a lesion near an immobile structure or an orifice, a fusiform excision, double V-to-Y-plasty, or rotation flap would put some pull against the structure, increasing the chance of breakdown or cosmetically unappealing scars. The A-to-T-plasty or double advancement flap can close the defect without pulling skin from the direction of the structure. The example shows closures near the mouth but would apply similarly to lesions near the eye, anal edge, or vulva. 
A fusiform excision that lines up with the lines of least skin tension will probably cause excessive vertical tension, thereby potentially significantly raising the edge of the lip, pulling down the nasolabial fold (and possible the inferior edge of the nose), and distorting the local anatomy. Poor choice.  
Figure 7
Figure 7
The O-to-Z-plasty would pull from the direction of the nose (limited tissue to pull), possibly distort the nasolabial fold, and may lift the end of the mouth. Not a good choice.  
Figure 8
Figure 8
Rotation flap alters the nasolabial fold, alters the local contour, and may alter the hair pattern of the mustache. Not a good choice.  
Figure 9
Figure 9
Advancement flaps will close the defect, maintain the hair patterns, and not pull on the mouth but may distort the glabella and the nasolabial fold. Adequate choice.  
Figure 10
Figure 10
V-to-Y-plasty will close the defect and maintain the hair patterns but may pull up at the edge of the mouth and pull down on the nasolabial fold. Adequate choice.  
Figure 11
Figure 11
A-to-T-plasty works well because it does not pull tension from the lip, and the skin that is moved matches the skin around it well (the mustache will look normal). Good choice.  
Figure 12
Figure 12
 
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