Abstract Purpose: Our aim was to determine the outcome of arthroscopic-assisted reduction with bilateral buttress plate fixation for the treatment of closed complex tibial plateau fractures. Type of Study: Case series. Methods: 18 consecutive patients (12 men, 6 women) with complex tibial plateau fractures were enrolled in this prospective study. All patients underwent arthroscopic-assisted bilateral buttress plate fixation of closed complex tibial plateau fractures. The average age at operation was 35 years (range, 23 to 45 years). The follow-up period ranged from 39 to 69 months, with an average of 48 months. Using the Schatzker classification, there were 11 type V and 7 type VI fractures. The clinical and radiological outcomes were determined according to Rasmussen’s system. Results: All of the 18 fractures united. Overall, 4 (22%) patients were rated as excellent, 12 (67%) good, and 2 (11%) fair. Secondary osteoarthritis appeared in 3 injured knees (16.7%). One patient had a wound dehiscence (3 cm long) of the medial incision. Condylar joint surface depression was noted in 3 patients without functional instability. Two patients had valgus alignment between 10° and 15°. Two patients had the paresthesia over the lateral calf. There were no complications directly associated with arthroscopy in any of the 18 patients. No deep vein thrombosis, infection, or knee stiffness was found at final follow-up. Conclusions: Arthroscopic-assisted reduction with bilateral buttress plate fixation for complex tibial plateau fractures allows accurate fracture reduction, diagnosis, and treatment of associated intra-articular lesions, and less dissection than open reduction internal fixation.