“…When designed over mobile muscle bellies (e.g., in the proximal thigh), release of the deep fascia even on one side can provide significant advancement subject to local tissue quality. 23 The keystone flap has demonstrated a growing diversity of clinical applications, 7-9 including coverage of large defects of the trunk, 10 limb, 13,14,21,26 groin, 23 perineum, 15 myelomeningocele, 27 and head and neck. 28 Previous modifications include a "yin yang" reconstruction, 29 including partial undermining and interdigitation of bilateral keystone flaps, 7 and the "omega variant," where both limbs of a single keystone are folded into a horseshoe shape.…”