Gait function is one of the most important components of functional outcome evaluation in patients with a tumor around the knee. In addition to walking at a preferred speed, the patients might be sometimes required to walk fast in daily life (e.g., schooling and working) because the major types of bone tumors often occur in adolescence and young adults. Therefore, recovering the ability to walk fast would increase the quality of life of these patients. To clarify which parts of the lower limb are exerted while walking fast, we investigated the kinematic and kinetic changes during fast walking in patients who underwent endoprosthetic knee replacement after bone tumor resection. Laboratory-based gait analysis was performed on eight patients who had undergone endoprosthetic knee replacement following resection of a tumor around the knee. Patients walked at a preferred and faster speed, and the gait parameters were compared between the two walking speeds for each leg. To increase walking speed, patients tended to rely on the bilateral hip, ankle, and contralateral knee to generate additional power. Kinetic analysis showed that involved-side vertical body support was not significantly increased during late stance to increase walking speed, which was associated with a small increase in ankle plantarflexion moment and concentric power. These results suggest to patients after knee reconstruction how to effectively increase their walking speed or redistribute the mechanical load on the muscles and joints to prevent excessive stress on the lower limbs. (C) 2014 Elsevier B. V. All rights reserved.