SKIN FLAP CLOSURE BY DERMAL LASER SOLDERING - A WOUND-HEALING MODEL FOR SUTURELESS HYPOSPADIAS REPAIR

Objectives. Laser tissue soldering (LTS) with the diode laser and huma n albumin-hyaluronate-indocyanine green solder is a safe and effective method of providing al? immediate leak-free closure during hypospadia s repair. In this report, we compare the physiology, histology, and im munohistochemistry of wound healing following LTS and suturing in a ra t skin flap model. Methods. A 4 x 5-cm skin flap was raised and bisect ed (4 cm) on the dorsum of 48 Sprague-Dawley rats, The central wound w as either closed from a dermal approach by suturing or LTS or left ope n, and studied at 0, 3, 5, 7, 10, 14, and 21 days postoperatively. An intraoperative comparison was made between suturing and LTS with respe ct to operative time. Postoperatively, flaps were excised for tensiome tric analysis, and sections were stained with hematoxylin-eosin to def ine wound architecture, Resting skin temperature, laser exposed temper ature without solder, and maximum temperature with solder (one drop) w ere measured at the level of the deep dermis, superficial striated mus cle layer, and within the solder. Mean peak temperatures were recorded during a I-minute laser activation time, Results. Mean continuous sut uring time (4.9 +/- 1.1 minutes) was significantly (P <0.001) faster t han either LTS (7.7 +/- 0.77 minutes) or discontinuous suturing (8.2 /- 0.62 minutes). Two seromas (sutured) and two instances of partial w ound dehiscence (1 sutured, 1 LTS) were noted. Tensile strength was in creased significantly (P <0.001) for up to 5 days in the LTS group, bu t was equal to suturing at 7 and 10 days. Immediate tensile strength a fter LTS was equivalent to a 7-day healed wound, At 14 days, wounds in itially left open and those closed by LTS were stronger than sutured w ounds (P <0.05). There was no evidence of thermal injury or foreign bo dy reaction in the LTS group, Solder was incorporated within the dermi s in all wounds at 21 days. Laser activation of solder resulted in sig nificant increases in temperature at all three tissue levels: 65.0 +/- 5.2 and 69.9 +/- 6.8 degrees C in the deep and superficial skin (no s ignificant difference between the two), and 101 +/- 15.6 degrees C wit hin the solder (P <0.001 versus superficial and deep skin). Conclusion s. Our results indicate that sutureless dermal LTS of skin flaps provi des increased tensile strength for up to 7 days, with relatively great er tensile strength provided within the first 5 days, Our laser techni que does not appear to alter the normal wound healing process, Rather, solder-tissue interaction initially, and extracellular matrix infiltr ation of solder later, provide the basis for improved wound strength, For hypospadias repair using skin flaps, these wound attributes may pe rmit sutureless surgery. (C) 1997, Elsevier Science Inc. All rights re served.