Objective:
Reconstruction of through-and-through composite oromandibular defects (COMD) with the free fibula osteocutaneous flap (FFOCF) has been challenging. Due to defect complexity, additional flaps are often needed, extending surgical durations and heightens associated risks. With the intention to minimalize harvesting sites, numbers of anastomosis, and consequently shortening operation time length, and decreasing risk of anesthesia, this case presents an innovative flap design involving a single FFOCF for COMD reconstruction.

Case presentation:
A 62-year-old man with squamous cell carcinoma of left lower gingiva, underwent induction chemotherapy and ablative surgery, resulting in a through-and-through COMD. For reconstruction, the FFOCF was osteotomized into two segments, with a 5cm length of space in between. The skin paddle was then divided into two islands based on each perforators, while preserving the vascular pedicle. The distal segment was rotated for 180 degrees, creating two skin islands on opposing sides, enabling repair of intraoral and extraoral cheek-skin defects. After the flap has been inset, the two fibula bone segments were bridged with miniplates and screws, and microvascular end-to-end anastomoses was performed as standard. The post-operative period passed under standard medical management, with no relevant complications. Subsequent follow-up at three months revealed favorable clinical manifestations and patient contentment.

Conclusion:
The nunchaku-like FFOCF reconstructs intra-oral, extra-oral, and bony defects, presenting a viable option for reconstructing through-and-through COMD with a single free fibula flap. With customized angle of fibula segments, this flap design solves the problem of over-extension or kinking of septocutaneous perforators. Precise measurement, careful consideration of anatomical variations and experienced surgical expertise are required.