Objective To investigate the effectiveness of lateral condyle sliding osteotomy (LCSO) in total knee arthroplasty (TKA) for the treatment of lateral femoral bowing deformity. Methods The clinical data of 17 patients with lateral femoral bowing deformity treated by LCSO during TKA between July 2018 and July 2020 was retrospectively analysed. There were 3 males and 14 females, with an average of 63.2 years (range, 58-68 years). The etiology of lateral femoral bowing deformity included 12 cases of femoral developmental deformity and 5 cases of femoral fracture malunion. Kellgren-Lawrence classification of knee osteoarthritis was 4 cases of grade Ⅲ and 13 cases of grade Ⅳ. The preoperative hip-knee shaft was 9.5°-12.5° (mean, 10.94°). The disease duration was 3-25 years (mean, 15.1 years). The mechanical lateral distal femur angle (mLDFA), hip-knee-ankle angle (HKA), and mechanical axis deviation (MAD) of the distal femur were measured before operation and at last follow-up to evaluate the correction of extra-articular deformities in the joints and the recovery of mechanical force lines of the lower extremities. The knee society score (KSS) knee score and function score, visual analogue scale (VAS) score, knee joint range of motion (ROM) were used to evaluate effectiveness. The knee varus/valgus stress test and osteotomy healing by X-ray films were performed to evaluate the joint stability and the safety of LCSO. Results All incisions of the patients healed by first intention after operation, and there was no early postoperative complication such as infection of the incision and deep vein thrombosis of the lower extremities. All 17 patients were followed up 12-36 months, with an average of 23.9 months. The osteotomy slices all achieved bony healing, and the healing time was 2-5 months, with an average of 3.1 months. After operation, the knee varus/valgus stress tests were negative, and there was no relaxation and rupture of the lateral collateral ligament, instability of the knee joint, loosening, revision and infection of the prosthesis occurred. At last follow-up, mLDFA, HKA, MAD, knee ROM, VAS score, KSS knee score and function score significantly improved when compared with preoperative ones (P<0.05). Conclusion LCSO is effective and safe in TKA with lateral femoral bowing deformity. Extra-articular deformities are corrected intra-articularly. The mechanical force line and joint balance of the lower extremities can be restored simultaneously in an operation.