We evaluated in this study indications, surgical technique, and results of wedge plates for fixation in proximal tibia medial opening wedge osteotomy. Fifty-eight knees in 56 consecutive patients (9 men, 47 women; mean age 52 years; ranging between 36 and 66 years) with medial compartment osteoarthrosis were treated with proximal tibia medial open-wedge osteotomy. For fixation, plates which were designed by the first author and which support the osteotomy surface with wedge-shaped projections were used. The plates were either rectangular in shape with two or four holes or had an inverse "L" shape with four holes, and had bearing metal wedges of varying heights from 5 to 15 mm. Tricortical (n=8) and bicortical (n=43) iliac bone autografts and allografts (n=7) were used. The average follow-up time was 21 months (ranging between 6 and 44 months). The mean preoperative tibiofemoral angle was 4.6 degrees varus (0 degrees-11 degrees) while it was 5.6 degrees valgus (2 degrees-11 degrees) postoperatively. The mean preoperative HSS score was 58 (range 51-75) and it was found 89 (range 79-96) postoperatively. As complications, lateral tibial plateau fracture in 5 knees (8.6%) and lateral cortex fracture in 15 knees (25.8%) were encountered during surgery. Deep vein thrombosis in two cases (3.4%) and nonfatal pulmonary embolism in one case (1.7%), delayed wound healing in two knees (3.4%), and delayed union as well as breakdown of a distal screw in one knee (1.7%) were encountered postoperatively. In conclusion, using wedge plates for fixation of proximal tibia medial opening wedge osteotomy in the treatment of medial osteoarthritis with unicompartmental involvement of the knee, provides adequate stabilization to allow early movement for functional rehabilitation and keeps the obtained correction level.