On the other hand, the width of functional skin/cm excised lesion ranged from 1.1 to 5.6 cm, with an average of 3.1 cm (Fig. 3B). Five of 13 patients required revision surgery during the postoperative course (Fig. 4B). The AUC of the ROC curve was 0.98, which indicated that the test had high accuracy, and the cutoff points determined by Youden index was 3.4 cm, and the second recommendation was 2.4 cm. The sensitivity and specificity were 100% and 87.5%, respectively, at 3.4 cm, whereas the sensitivity and specificity were 80% and 100%, respectively, at 2.4 cm.
The need for revision surgery was statistically higher in patients in the range of less than 7 ml/cm2 lesion and width of functional skin of less than 3.5 cm or 2.5 cm/cm lesion (P < 0.05).
The calculated values for the treatment of scars tended to be greater in both volume and width. As for the water volume of the expanders/cm2 lesions, it was only in the scar cases that more than 21 ml was required, and the functional skin width of 4.5 cm or more/cm lesion was needed only in cases of scar and sclerodermie en coup-de-sabre.
No tissue in the human body adequately mimics the hair-bearing scalp. While a small defect of the scalp can be covered with a local skin flap composed of adjacent scalp, large defects are eventually treated by either skin grafts or free flaps. Unfortunately, the postoperative appearance following such treatments can be unattractive. Tissue expansion, especially in the scalp region, is an effective technique that enables tissue to be transferred from the adjacent hair-bearing areas. Furthermore, the scalp is also an ideal place for tissue expansion due to the rich blood circulation, thick overlying tissue, and the rigid support of the skull.8
Although the concept of tissue expansion is simple, selection of the proper size implants for tissue repair is not. Insufficient expansion leads to inadequate covering of the lesion, the need for an additional skin graft, scar widening, or “stretch back.”15 Radvan6 and Morgan and Edgerton16 reported that the expander base should be the same size as the defect. On the other hand, Manders et al2 suggested placing as large an expander as possible. These recommendations were based on empirical observations. van Rappard et al14 studied the surface area gained by tissue expansion using 3 approaches: mathematical, in vitro, and in vivo (in pigs), and they concluded that the expander base should be roughly 2.5 times as large as the defect.
In our study, we considered the size of successfully expanded skin as it relates to the bulging of the expanders and the size of the base, and the skin available to cover the defect is obtained by subtracting the width of the bottom surface for covering the expander insertion portion from the width of all the expanded skin surface. In clinical practice, the width of the expander is constant and easier than considering the real skin width. For these reasons, we defined the hypothetical functional skin based on the width of the expanders. We also predicted that there might be some relationship with the volume of the tissue expanders. Our study, therefore, analyzed the volume and the width of the stretched skin of the tissue expanders in the cases undergoing surgery.
Our results revealed that cases with a volume of less than 7 ml/cm2 lesion and a width of functional skin less than 2.5 or 3.5 cm/cm lesion required revision surgery more frequently than cases with any other ranges. It was considered that the cases in these small ranges might experience scar widening or deformity caused by scar contracture, although the surgery had appeared to have been successful due to the total resection of the lesion after completion of the surgery. Based on the observation that the need for revision surgery was statistically higher in the patients with a width of functional skin below 2.5 and 3.5 cm/cm lesion, it can be said that those cases in which the functional width is between 2.5 and 3.5 cm/cm lesion may be considered borderline. On the other hand, there were no postoperative complications due to excess expansion, that is, hematoma, infection, and remarkable dog-ear.
Based on the above findings, tissue expanders that generate skin at least 2.5 times the width of the defect and have a volume more than 7 ml/cm2 defect are necessary for successful scalp reconstruction without complications.
We also observed that a wider width of functional skin and a larger volume of tissue expanders were needed in some scars, which suggests that the amount of skin required for scars varies according to the degree of scar contracture, and are more than that required by any other type of lesions. Because the size of the skin defects created by removing the scar and by the release of the scar contracture are often much larger than the scar itself, successful repair of such defects sometimes requires 2-fold more or even greater skin width and volume of expanders compared with other lesions. Furthermore, in the cases of treatment for scars, it is necessary to plan in consideration of the primary diseases that caused the scars.
The present results suggest that the size of tissue expanders should be selected based on the width and area of the lesion. In applications involving scars, preoperative evaluation of the degree of the latent contracture should be performed before choosing the size and number of tissue expanders.
We analyzed 21 patients with scalp lesions in whom tissue expanders had been inserted and found that tissue expanders that generate skin at least more than 2.5 times the width of the defect and have volumes of more than 7 ml/cm2 defect are needed for successful scalp reconstruction without complications. For scar repairs, the size and volume of the expanders tended to be larger than those required for any other lesions.
1. Argenta LC, Watanabe MJ, Grabb WC.. The use of tissue expansion in head and neck reconstruction. Ann Plast Surg. 1983;11:31–37
2. Manders EK, Schenden MJ, Furrey JA, et al. Soft-tissue expansion: concepts and complications. Plast Reconstr Surg. 1984;74:493–507
3. Joss GS, Zoltie N, Chapman P. Tissue expansion technique and the transposition flap. Br J Plast Surg. 1990;43:328–333
4. Gibstein LA, Abramson DL, Bartlett RA, et al. Tissue expansion in children: a retrospective study of complications. Ann Plast Surg. 1997;38:358–364
5. Neumann CG.. The expansion of an area of skin by progressive distention of a subcutaneous balloon; use of the method for securing skin for subtotal reconstruction of the ear. Plast Reconstr Surg (1946). 1957;19:124–130
6. Radovan C. Tissue expansion in soft-tissue reconstruction. Plast Reconstr Surg. 1984;74:482–492
7. Nordström RE, Devine JW. Scalp stretching with a tissue expander for closure of scalp defects. Plast Reconstr Surg. 1985;75:578–581
8. Fan J, Yang P. Aesthetic reconstruction of burn alopecia by using expanded hair-bearing scalp flaps. Aesthetic Plast Surg. 1997;21:440–444
9. Gürlek A, Alaybeyoğlu N, Demir CY, et al. Aesthetic reconstruction of large scalp defects by sequential tissue expansion without interval. Aesthetic Plast Surg. 2004;28:245–250
10. Motamed S, Niazi F, Atarian S, et al. Post-burn head and neck reconstruction using tissue expanders. Burns. 2008;34:878–884
11. Nazerani S, Motamedi MH.. Reconstruction of hair-bearing areas of the head and face in patients with burns. Eplasty. 2008;8:e41
12. Fan J, Liu L, Tian J, et al. The expanded “flying-wings” scalp flap for aesthetic hemiscalp alopecia reconstruction in children. Aesthetic Plast Surg. 2009;33:361–365
13. Akobeng AK.. Understanding diagnostic tests 3: receiver operating characteristic curves. Acta Paediatr (Oslo, Norway: 1992). 2007;96:644–647
14. van Rappard JH, Molenaar J, van Doorn K, et al. Surface-area increase in tissue expansion. Plast Reconstr Surg. 1988;82:833–839
15. Nordström RE. “Stretch-back” in scalp reductions for male pattern baldness. Plast Reconstr Surg. 1984;73:422–426
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16. Morgan RF, Edgerton MT. Tissue expansion in reconstructive hand surgery: case report. J Hand Surg Am. 1985;10:754–757