Background: The treatment of Genu valgum with grade IV OA is a challenge in TKR. For this reason it is important to correct the deformity during surgery even if it does not completely eliminate the increased risk of failure. Methods: This is a prospective study was conducted on 25 knees (22 patients) suffering from grade IV OA with genu valgum presented to Al-Azhar University Hospitals and Agouza Charity Hospital from October 2013 to November 2016, mean follow-up duration is 24 months no missed patients in the follow-up, three of this patients (12%) had bilateral genu valgum. Only 15 knee (60%) had about 10 degrees valgus deformity (type 1), 5 knees (20%) had about 11-20 degrees valgus deformity (type 2) and 5 knees (20%) had 21-30 degrees valgus deformity (type 3). Patients had a mean age at the time of surgery of 59 years (range from 50 to 68 years), the group of patients included 17 females (77%) and 5 males (23%), 11 patients (50%) had the right knee only replaced (9 females and two males), 8 patients (36%) had left one only (6 females and two males), while 3 patients (12%) had bilateral TKR (2 females and one male). Result: At the last follow-up for all patient's the average Hospital for Special Surgery knee score was 87.82 (ranging from 72 to 94) compared with average preoperative Hospital for special surgery knee score of 66.32 (ranging from 48 to 78), with an average increase of 21.50. Conclusion: In type I valgus deformity we do medial parapetellar approach, release of the posterolateral capsule then we may proceed in our sequence of soft tissue release, we prefer to use PS implant. In type II valgus deformity we do medial parapetellar approach, then we proceed in our sequence of soft tissue release (ITB, POP, LCL, LHG + LCL, POP, ITB + LHG). The choice of the level of constraint was on the operative field, based on the integrity and functionality of the MCL. If there is a medial residual instability do not perform a medial tightening, but switch to a higher constrained implant (CCK) instead of PS implant. In type III valgus deformities we do lateral parapetellar approach ± TTO then we prefer to use a CCK implant.