Moving from the O-Z flap to the O-S flap for scalp reconstruction: A new geometrical model

Abstract

The O-Z flap is the most commonly used local flap technique to repair round and oval scalp defects in clinical practice. Preoperative flap marking is one of the major technical issues of this reconstructive method and it is essential to achieve an optimal outcome. Nevertheless, the absence of a unified arc design scheme could significantly limit the use of this useful and reliable technique, and flap drawing is sometimes based more on the surgeon's experience than on a real geometrical model. Our aim was to describe an intuitive and standardizable method for O-Z flap marking, that we called "O-S flap," based on a simple and easily replicable geometrical pattern. We reported our experience in this case series of eight patients with skin tumors of the scalp who underwent scalp reconstruction with the "O-S flap" technique at our university hospital. Most patients had defects located on the vertex or parieto-occipital regions of the scalp. The area of the defects ranged from 7 to 78.5 cm². There were no cases of flap necrosis, wound infection, or positive margins, and no patients required revision surgery. We believe that our technical refinement represents a safe, easy, and reproducible method for O-Z flap marking. It follows a simple geometrical model which could be customized according to different clinical needs.

Keywords: Flap marking; O-S flap; O-Z flap; Scalp defects; Scalp reconstruction.

Figure 1

Design scheme of the O-S flap. Point O represents the center of the defect (gray circle) and it is the intersection of the diagonals of the rectangle A, D, E, and H. L and S are the points of tangency of the circle inscribed in the square B, C, F, and G. The distance LS represents the diameter of the defect and it represents the radius of the two opposing flaps (red and blue).

Figure 2

Preoperative picture of a 36-year-old male with a squamous cell carcinoma of the scalp measuring 5 cm. Two different pairs of opposing O-S flaps are drawn in red and blue (A). One-month follow-up picture showing satisfactory anatomical contour and aesthetic results, and no areas of alopecia (B).

Figure 3

Flap markings in a 75-year-old female with basal cell carcinoma of the parieto-occipital region of the scalp with a diameter of 5 cm (A). Immediate postoperative picture showing a tensionless closure of the defect and a good flap vascularization (B).

Figure 4

Preoperative picture of a 79-year-old male with an actinic keratosis of the vertex (A). One-week follow-up picture showing good flap viability (B).

Figure 5

Preoperative picture of an 87-year-old male with squamous cell carcinoma of the vertex. The diameter of the defect was 8.5 cm (A). Intraoperative pictures showing the defect depth (down to the calvarium), and the two flaps raised (B-C). Immediate postoperative picture showing wound closure (D). Three-month follow-up picture showing excellent cosmetic outcome (E).

Figure 6

Preoperative picture of an 80-year-old male with squamous cell carcinoma of the vertex. The diameter of the defect was 10 cm (A). Intraoperative pictures showing the defect depth (down to the calvarium), and the two flaps raised (B). One-month follow-up picture showing excellent cosmetic outcome (C).