This video reviews six techniques for a slope-reducing anterior closing wedge osteotomy of the proximal tibia. The video also discusses the case presentation of a patient with a posterior tibial slope of 17&[deg] and recurrent knee instability in whom anterior cruciate ligament reconstruction failed. A proposed algorithm and technical considerations for an accurate corrective osteotomy are reviewed. A closing wedge osteotomy can be performed below, at, or above the level of the tibial tubercle. Indications for a closing wedge osteotomy include: (1) second or third revision anterior cruciate ligament reconstruction in a patient with a posterior tibial slope greater than 12&[deg], (2) primary anterior cruciate ligament reconstruction in a patient with a posterior tibial slope greater than 15&[deg] and a proximal tibial posterior cortex with a kinked can appearance, and (3) patients aged 50 years or younger who are athletically active and wish to continue reasonable athletic activity. Contraindications for a closing wedge osteotomy include Kellgren-Lawrence grade 4 osteoarthritis, more than 10&[deg] of knee hyperextension, and patella alta. Our preferred method for measurement of posterior tibial slope involves measuring the angle between the proximal tibial anatomic axis and the medial tibial plateau tangent. We recommend measuring a patient’s patellar height preoperatively. The goal of a corrective osteotomy is to maintain a normal Linclau ratio of 1. To avoid patella alta, we suggest distalization of the tubercle with an amount equal to the height of the closing wedge. In planning for a corrective osteotomy, we calculate the height of the closing wedge using tan &[theta] geometry and calculate the width of the proximal tibia. The cutoff value is 58 mm of tibial width at the level of the osteotomy; anything below this cutoff value results in a ratio that is no longer 1:1 for wedge height to the degree of correction. Finally, we predict the degree of knee hyperextension resulting from the anterior closing wedge osteotomy by measuring the change in heel height before and after the osteotomy. Heel height can be used as a 1:1 surrogate for the degree of hyperextension after an osteotomy. The cutoff value is 58 cm of limb length; anything above this cutoff value results in a ratio that is no longer 1:1. Reliable fixation of an anterior closing wedge osteotomy can be achieved with the use of staples or via locking plate fixation. The keys to avoid complications are meticulous preoperative planning and careful execution of the procedure.