Background: Spare-part surgery is widely accepted and offers an option in extremely traumatized patients for reconstructive maneuvers. Standardized techniques are lacking, and the therapy needs to fit the patient’s clinic. Materials and Methods: In a woman with necrosis of almost all extremities due to septic infection, we used the lower leg as a free osteocutaneous flap to reconstruct a basic hand function after amputation. The fibula segment was buried alongside the remaining first metacarpal bone. On the hand stump, 2 short metacarpals were lengthened using the remaining 2 metacarpals as osteovascular on-top plasties. The flap was microsurgically anastomosed end-to-side to the ulnar artery. After 3 months, the buried fibula was trimmed to the necessary thumb length and fixed to the local metacarpal I stump. Secondary procedures were performed to deepen the first web space. Results: The patient is now able to manage her daily life. Also, she is able to put on her prosthesis on both legs and walk without aids. Conclusions: To our knowledge, this is the first description of successful microvascular transfer of an osteocutaneous free flap from an amputated lower leg of this size and could present a valuable technique for other cases.