Treatment options for severely damaged finger joints include amputation, arthroplasty, arthrodesis, and reconstruction using nonvascularized or vascularized joint transfers. The thumb contributes significantly to global hand function, and functioning metacarpophalangeal and interphalangeal joints are crucial. When 2 adjacent joints are damaged by trauma, vascularized joint transfer from an injured index finger to the thumb is an option to maximize remaining thumb function. Complex composite injuries involving joints, soft tissues, and tendons require customized reconstructive solutions to retain and optimize hand function. We present a case of component separation of an injured index finger as the donor area for 2 flaps to reconstruct a complex bone, joint, and soft tissue thumb defect, which resulted in a high level of patient satisfaction and a return to heavy manual work.