Five-sector grid. AT, adductor tubercle (encircled in white); L, lateral; M, medial; I, row 1; II, row 2; III, row 3; Green dashed lines, posterior part of the medial and lateral femoral condyle; Red dot, osteotomy hinge; Red circle, inflection point, defined as the point at which the distance between the medial cortical bone and Line 4 reaches 2 mm; Line 5, tangential to the lateral facet of the medial femoral condyle; Line 4, tangential to the medial femoral cortical bone; Line 3, tangential to the apices of the posterior part of the medial and lateral femoral condyle; Line 2, parallel to Line 3 and crossing the proximal part of the AT; Line 1, parallel to Line 3 and crossing the inflection point