Chronic anterior laxity due to anterior cruciate ligament (ACL) deficiency is associated with the development of tibiofemoral osteoarthritis (OA) and frequently varus malalignment. Isolated ACL reconstruction (ACLR) can restore anterior knee stability in such cases, but does not mitigate progression of OA. Proximal tibial osteotomy (PTO) has long been an accepted treatment for medial compartment OA with varus malalignment in young and middle age patients and also plays a large role in knee restoring knee stability in the setting of unstable arthritic knee. Chronic ACL injury with varus osteoarthritis should be treated with HTO alone or HTO combined with ACL reconstruction, depending on the patient`s age, activity level and the reported instability. Proximal tibial osteotomy corrects the varus alignment and offloads the medial compartment and improves the result of ligament reconstruction.