['Malignant tumors in proximal tibia invading fibula usually have a large tumor volume and are adjacent to the neurovascular bundles. The prognoses and functional outcomes of limb salvage for these patients are uncertain. We, therefore, asked whether patients with limb salvage surgery for malignant tumors in proximal tibia invading fibula had poorer oncological prognosis, higher complication rate, and lower postoperative functional score compared with patients without fibula invasion.', 'We retrospectively reviewed 129 patients with primary malignant tumors in proximal tibia. The patients were divided into two groups, i.e., with and without proximal fibula invasion. A total of 35 and 94 patients were in the group with and without fibula invasion, respectively. Data on demography, operation time, blood loss volume, complications, survival time, and postoperative function were compared between two groups.', 'The patients with fibula invasion had a longer mean operative time (p = 0.011), less percentage of obtaining wide surgical margin (p = 0.027), lower estimated 5-year survival rate (p = 0.05), higher tumor local recurrence rate (p = 0.042), and earlier postoperative complications (p = 0.01) than the patients without fibula invasion. The difference in postoperative functions as evaluated by the Musculoskeletal Tumor Society functional scoring system was not significant (p = 0.233).'] Are poor prognosis and complications common in limb salvage surgery for malignant tumors of the proximal tibia invading the fibula?