Mechanical alignment has been overlooked as an important contributor to knee stability with respect to collateral ligament laxity. The detrimental effects of varus or valgus limb malalignment become more obvious when the restraining force is lost because of ligamentous injury especially on the medial or the lateral/posterolateral side. Even with repair or reconstruction of these injuries, with repetitive load, the ligament will eventually fail to restore its structure and strength, resulting in failure and secondary restraint laxity. We have found that realignment of the limb is the most important factor in restoring a functional limb. After realignment, joint laxity, if persistent, can be addressed successfully with ligamentous reconstruction. Diagnosis and treatment of limb malalignment cannot be ignored in the management of chronic ligamentous instabilities, especially those with prior failed reconstruction. Our approach to these difficult problems and the preferred techniques of osteotomies on both tibial and femoral sides are described.