The simultaneous reconstruction of a skin defect and lost extensor mechanism of the knee joint is difficult. We present a 31-year-old male who lost the patella and had a 9 × 10 cm skin defect after a total patellectomy for an infected open patellar fracture. A composite anterolateral thigh (ALT) flap including vascularized skin and fascia lata (FL) was elevated. The FL was folded and sutured to the remaining patellar tendon. The skin flap covered the skin defect. The wound healed uneventfully. Thirty months later, the active range of motion of the knee joint was 0°-120° and the extension strength of the knee joint was normal. He could stand on his right leg and walk without assistance. The composite ALT flap is a valuable option in knee reconstruction after a total patellectomy.