Subcision is a surgical procedure akin to keyhole surgery. It can be performed by dermatologists & plastic surgeons using many instruments including the Taylor Liberator, cannulas, modified blades, Nokor Needle, hook devices, flat instruments & sharp stripping instruments. This procedure is best reserved for severe tethered scars involving facial areas. Subcision is often combined with lasers, RF microneedling & deep focal peels.
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How to tell if you are a candidate for subcision?
Subcision is best reserved for acne scars with deep attachments. In most cases a real time clinical examination is required. Diagnostic clues include-

Tethering or puckering at rest
Tethering upon animation (smile, grin, frown)
Inability to distend skin upon gentle stretching (Grade 4/B scars)
Fibrosis upon palpation
The dimple sign-squeeze either side of the scar. If there’s a dimple, there’s probably an attachment to the deep layers of skin