The defined Gruen zones of the periprosthetic side. The length from the upper edge of the prosthesis stem's medial side to its distal end is divided into three equal parts. The 2‐cm area of the distal end of the prosthesis is zone 4, and the outer and inner side of the prosthesis from top to bottom is, respectively, zone 1 to 3 and zone 5 to 7.