Simultaneous Versus Sequential Fractional CO2 Laser and Subcision Combination for Post-acne Atrophic Scars: A Split-face Comparative Study.

"Fractional CO2 laser is performed immediately following subcision. Subcision is operated in all participants using an 181/2G Nokor needle (BD Nokor™ Admix Needles, United States). The insertion depth is at the dermal-hypodermal junction. The subcision needle is advanced and retracted in a tunneling motion to penetrate the fibrotic scar tissue, then slid in a direction parallel to the skin's surface in order to detach the scar from its tethers.~All participants undergo FrCO2 laser (10 600-nm eCO2 laser, Lutronic Corporation, Goyang, Korea) with the parameters following the suggested regimen at static mode: 120 μm beam size, 30 W peak power, 30 - 120 mJ pulse energy, 50-75 spots/cm2 density, with two passes: (1)Only the atrophic scars are treated using a 4mm square or circle pattern, 100-120 mJ pulse energy, and 50 spots/cm2 density. (2)The whole half side of the face is treated using a 12mm square pattern, 30-40 mJ pulse energy, and 75 spots/cm2 density, \<10% overlap."

"Fractional CO2 laser conducted two weeks after subcision. Subcision is operated in all participants using an 181/2G Nokor needle (BD Nokor™ Admix Needles, United States). The insertion depth is at the dermal-hypodermal junction. The subcision needle is advanced and retracted in a tunneling motion to penetrate the fibrotic scar tissue, then slid in a direction parallel to the skin's surface in order to detach the scar from its tethers.~All participants undergo FrCO2 laser (10 600-nm eCO2 laser, Lutronic Corporation, Goyang, Korea) with the parameters following the suggested regimen at static mode: 120 μm beam size, 30 W peak power, 30 - 120 mJ pulse energy, 50-75 spots/cm2 density, with two passes: (1)Only the atrophic scars are treated using a 4mm square or circle pattern, 100-120 mJ pulse energy, and 50 spots/cm2 density. (2)The whole half side of the face is treated using a 12mm square pattern, 30-40 mJ pulse energy, and 75 spots/cm2 density, \<10% overlap."

Fractional CO2 laser (10 600-nm eCO2 laser, Lutronic Corporation, Goyang, Korea) on both sides of the face sequentially with a two-week interval between sessions for each face's side by a single physician, with the parameters following the suggested regimen at static mode: 120 μm beam size, 30 W peak power, 30 - 120 mJ pulse energy, 50-75 spots/cm2 density, with two passes. At the first pass, only the atrophic scars are treated using a 4mm square or circle pattern, 100-120 mJ pulse energy, and 50 spots/cm2 density in the static operating mode. At the second pass, the whole half side of the face is treated using a 12mm square pattern, 30-40 mJ pulse energy, and 75 spots/cm2 density in the static operating mode with less than 10% overlap.

Subcision is operated in all participants using an 1812G Nokor needle (BD Nokor™ Admix Needles, Becton, Dickinson and Company, New Jersey, United States). The operation sites are sterilized with alcohol pads and injected intradermally with a solution of 2% lidocaine. After obtaining appropriate anesthesia, a Nokor needle is inserted into the skin close to the depressed scars and progressed until it lays precisely under the scar. The insertion depth is at the dermal-hypodermal junction. Initially, the subcision needle is advanced and retracted in a tunneling motion to penetrate the fibrotic scar tissue. Once the fibrous mass has been sufficiently fractured, the needle is slid in a direction parallel to the skin's surface in order to detach the scar from its tethers. For densely fibrous scars, several needle insertion sites are used to undermine the defect from various angles.

Preoperative, lidocaine 2.5% and prilocaine 2.5% cream (EMLA 5%, eutectic mixture of local anesthetic; AstraZeneca LP, Wilmington, DE, USA) is applied under occlusion for 60 minutes prior to the removal of local anesthetics

A 500 mg paracetamol-based oral analgesic (Efferalgan, Upsa SAS, France) is administered right before the procedure.

The operation sites are sterilized with alcohol pads and injected intradermally with a solution of 2% lidocaine.