The O-to-Z plasty is a versatile closure technique used for large defects that are not appropriately closed with a fusiform (elliptical) excision technique. Because of the multiple clinical indications, the O-to-Z plasty can be readily learned by generalist physicians and used frequently in practice. Advantages of the technique include the sparing of tissue, closure aligning with the lines of least skin tension, and production of a broken line (Z-shaped) final scar. The O-to-Z flap technique generally produces excellent cosmetic results.
The O-to-Z plasty incorporates advancement and rotation techniques, and some authors characterize it as a transposition flap. The O-to-Z flap can be envisioned as a large fusiform excision, with only the central circular area around the lesion excised (see Figure 2.) On each side of the central circular area, only one of the arms of the fusiform excision is incised. A flap is created on each side, and these two flaps are joined centrally to create a final Z-shaped scar.
Large fusiform excisions can result in the removal of a large amount of tissue and subsequent pull on surrounding structures with closure of the wound. For instance, a large fusiform excision just above the eyebrow can produce permanent elevation of the eyebrow. Fusiform excisions on the upper lip can elevate the vermilion border. The O-to-Z plasty can obviate the difficulty of lateral pull on surrounding structures when closing the wound.
Skin flaps are most commonly performed on the face, where the blood supply is extensive. The O-to-Z plasty receives its blood supply through large pedicle bases (i.e., portion of the fusiform incisions that are not incised) and can sometimes work well even on nonfacial sites. As with all skin flaps, meticulous attention to hemostasis is required.
When the O-to-Z plasty is performed after skin cancer removal, it is preferable to ensure clear margins using frozen sections or Mohs' surgery before performing wound closure. Because these options may not be available to an office physician, a sufficient margin of normal-appearing skin must be removed around and beneath a cancer (usually at least 4 to 6 mm) before closure is attempted. Postprocedure pressure dressings are recommended to reduce hematoma formation beneath the flaps and the development of complications.
The O-to-Z plasty is based on the fusiform excision. After removal of the skin lesion (Figure 1A), the fusiform excision is designed so that the length is three times the width (Figure 1B). The fusiform excision is aligned so that the long axis is parallel to the lines of least skin tension.
(1) After removal of a skin lesion, a fusiform excision is designed so that the length is three times the width, and it is aligned so that the long axis is parallel to the lines of least skin tension.
In the O-to-Z plasty, only one incision line (i.e., arm) is performed on each side of the central circular excision. The incision lines are drawn to slope toward a theoretical central line. One incision arm is above the central line, and one incision arm is below the central line.
(2) One incision arm is drawn to slope toward a theoretical central line on each side of the central circular excision; one incision line is above, and the other is below the central line.
PITFALL: Make sure the incision arms are on opposite sides of the central line! Many novice practitioners have unintentionally incised both arms on the same side of the central line, necessitating performance of a fusiform excision or an advancement flap technique.
The central island of skin containing the tumor has been removed and sent for histologic analysis (Figure 3A). Gentle sloping lines are incised that end at the theoretical central line (Figure 3B). The arms are approximately 1.5 to 2 times the diameter of the central circular excision. The corners are squared to facilitate approximation of the flaps (Figure 3C).
(3) Gentle sloping lines are incised. They end at the theoretical central line, and each line approximately 1.5 to 2 times the diameter of the central circular excision.
The flaps are gently elevated with skin hooks, and horizontal undermining is performed with a no. 15 scalpel blade or scissors. The wider the undermining around the entire site, the easier it is to move the skin flaps together.
(4) Gently elevate the flaps with skin hooks, and perform horizontal undermining with a no. 15 scalpel blade or scissors.
The two flaps are brought together and anchored with one or two vertical mattress sutures. Corner stitches are placed in the flap tip corners. The elevated tissue formations at the ends of the arms are known as dog ears.
(5) Bring the two flaps together, anchor them with one or two vertical mattress sutures, and place corner stitches in the flap tip corners.
Triangular pieces of skin are removed, eliminating the dog ears and allowing the corners to lie flat (Figure 6A). The final closure is shown (Figure 6B).
(6) Remove the dog ears of skin.
This closure can be performed on the forehead above the eyebrow (Figure 7A), on the chin (Figure 7B), or beneath the chin (Figure 7C).
(7) Examples of clinical indications for the O-to-Z plasty: the forehead above the eyebrow, the chin, and beneath the chin.
Chapter 25 lists the codes used for reporting the adjacent tissue transfer procedures.
INSTRUMENT AND MATERIALS ORDERING
Appendix A lists the instruments included in a standard skin surgery pack. The comments on instruments in Chapter 26 also apply to the performance of O-to-Z plasty. Suggested suture removal times are listed in Appendix C, and a suggested anesthesia tray that can be used for this procedure is listed in Appendix G.
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