The "Trimeric" Anterolateral Thigh Free Flap: A Novel Technique for the Reconstruction of Complex Cranio-Orbital and Middle Skull Base Defects.

[BACKGROUND AND IMPORTANCE] The anterolateral thigh (ALT) free flap is a versatile reconstructive option for complex 3-dimensional defects of the head and neck. It can be tailored for cutaneous, fasciocutaneous, musculocutaneous, or flow-through configurations based on patient needs. Chimeric flaps comprise distinct tissue components on a shared vascular pedicle and allow simultaneous functional and aesthetic reconstruction in a single stage. We present a novel extension of this concept incorporating a third vascularized component to address multilayer skull base defects.

[CLINICAL PRESENTATION] A 65-year-old man with an atypical (World Health Organization Grade II) sphenoid wing meningioma infiltrating the left anterior and middle cranial base, infratemporal fossa, and masticator space developed necrotizing fasciitis and flap failure after initial resection. The resulting skull base defect involved the middle cranial fossa, orbit, and maxilla, with communication into the nasopharynx. Conventional staged reconstructions or local flaps were not feasible because of limited tissue diversity and recipient vessels. A "trimeric" ALT free flap was therefore designed, incorporating 3 tissue components: vastus lateralis muscle, tensor fascia lata, and rectus femoris muscle. Each of these was supplied by perforators from the descending branch of the lateral circumflex femoral artery. This configuration enabled reconstruction of the middle cranial fossa floor, vascularized dural coverage, and restoration of temporalis contour in a single operation.

[CONCLUSION] This first reported trimeric ALT flap achieved comprehensive restoration of complex cranio-orbital and skull base defects, providing a durable, vascularized, and anatomically adaptable solution for single-stage reconstruction.