OBJECTIVE: To summarize the surgical experience and clinical results of the first 89 fractures of the proximal tibia treated with the Less Invasive Stabilization System (LISS; Synthes, Paoli, PA). DESIGN: Retrospective analysis of prospectively enrolled patients into a database. SETTING: Academic level I trauma center. SUBJECTS/PARTICIPANTS: Eighty-seven consecutive patients with 89 proximal tibia fractures (AO/OTA type 41 and proximal type 42 fractures) treated by 2 surgeons. Seventy-five patients with 77 fractures were followed until union. The mean follow-up was 14 months (range: 3-35 months). There were 55 closed fractures and 22 open fractures. INTERVENTION: Surgical reduction and fixation of fractures, followed by rehabilitation. MAIN OUTCOME MEASUREMENTS: Perioperative and postoperative complications, postoperative alignment, loss of fixation, time to full weight bearing, radiographic union, and range of motion. RESULTS: Seventy of 77 fractures healed without major complications (91%). There were 2 early losses of proximal fixation, 2 nonunions, 2 deep delayed infections, and 1 deep peroneal nerve palsy. Other complications included a superficial wound infection and 3 seromas. Postoperative malalignment occurred in 7 patients with 6 degrees to 10 degrees of angular deformity (6 flexion/extension and 1 varus/valgus malalignments), and an eighth patient had a 15 degrees flexion deformity. In 4 patients, the hardware was removed at an average of 13 months because of irritation (5%). The mean time for allowance of full weight bearing was 12.6 weeks (range: 6-21 weeks), and the mean range of final knee motion was 1 degrees to 122 degrees . CONCLUSIONS: The LISS provides stable fixation (97%), a high rate of union (97%), and a low (4%) rate of infection for proximal tibial fractures. The technique requires the successful use of new and unfamiliar surgical principles to effect an accurate reduction and acceptable rate of malalignment.