Abstract Background: A major difficulty of primary total knee arthroplasty is the presence of bone defects, and may leads to unstable knee prosthesis. Commonly, it is located on the tibial surface of the joint; however the femoral side also can be affected. The defects are usually peripheral and not symmetrical. The main goal of total knee replacement is to restoring the alignment of mechanical axis, and reconstruction of bone defect with augment either wedge, or block, and stem extension can be added. Patients and methods: This prospective study includes thirty cases with mean age of 65 years; all patients had varus knee deformity greater than 20°. Mean follow-up period was 30 months. All the surgeries were performed by using of posterior stabilized implants. Anterior approach with medial para-pattelar exposure was used in all cases. Gap technique and ligamentous balance technique were performed in all surgeries. Bone loss was reconstructed by using of block or wedge augments with stem extension in all cases. The stem in all cases was press fit, and its length was 100 mm. The size of the metal wedge was calculated after performing the ordinary cut in the tibia. Mobilization was begun one day post-operatively. American Knee Society Score (AKSS) was used to evaluate the outcomes. Results: Average AKSS was 50 points pre-operatively and 85 points at the last visit. Patients with excellent outcome were 76.7% (23 cases), with good outcome were 16.7% (5 cases) and with fair outcome were 6.6% (2 cases). Complications were reported in three cases, two cases developed superficial infection and tourniquet paralysis was encountered in one case. Range of motion of the knee was improved post-operatively by 35±15°. Conclusion: Using of total knee prosthesis with metal augment in cases of medial tibial bone deficiencies can solve a major problem and improve the outcomes, and the addition of a modular medullary stem can gives a better implant stability.