Keystone Flap Type IIIB: A New Variation for Coverage of Defects at Joint Regions.

Soft tissue defect reconstruction at joint regions is a challenging problem due to the sparse excessive tissue and late complication of constrigent scar formation. Priorly irradiated tissue, often the case in sarcoma patients, is especially problematic. The keystone design perforator island flap is safe and reliable. We now present a new keystone flap design, which is particularly suitable for the reconstruction of large soft tissue defects at joint regions. It provides a cutaneous component without the need for a skin graft and therefore minimizes the risk of contracture. Donor site morbidity is negligible. Furthermore, it offers a favorable aesthetic result compared to other flaps, eg, a muscular flap. We propose a new keystone flap design as an extension of Behan's classification, the Keystone flap type IIIb.