Slotted acetabular augmentation of Staheli. A, Width of augmentation (WA) is determined preoperatively from standing anteroposterior radiograph of pelvis. Center-edge angle and 35-degree angle are drawn. Graft length (gl) is sum of WA and slot depth. B, Objective of procedure is to provide congruous extension of acetabulum. C, Details of extension. SEE TECHNIQUE 30.12.