Lateral and Anterior Closing Wedge "9/9" Degree Osteotomy to Correct Both Tibia Vara and Excessive Tibial Slope.

High tibial osteotomy is a key option for patients with unicompartmental overload or instability. Although coronal correction for varus deformity is well established, excessive posterior tibial slope (PTS) is increasingly recognized as a contributor to anterior cruciate ligament graft failure. Conventional strategies often require staged procedures, potentially delaying recovery and compromising bone stock. The "9/9 osteotomy" allows simultaneous correction of varus and excessive PTS in a single stage. The technique combines a lateral closing wedge osteotomy with an anterior retrotubercle closing maneuver. Preoperative planning uses long-leg standing and lateral radiographs to determine mechanical axis, medial proximal tibial angle, and PTS, which guide wedge dimensions and hinge position. Through a lateral approach, a lateral closing wedge is created toward a posteromedial hinge, followed by removal of an anterior wedge behind the tibial tubercle to decrease PTS. Fixation is performed with a lateral locking plate. The 9/9 osteotomy offers a reproducible single-stage solution for combined varus and excessive PTS, preserving bone stock and facilitating early rehabilitation.