We describe a technique of hemi-circumferential interposition grafting that allows placement of the cup in the anatomical position of the original acetabulum in the rare cases of post-Perthes or Perthes-like deformities of the femoral head combined with a steep and shallow acetabulum. This technique was performed on 10 hips (9 patients, with an average age of 56 years). One revision was performed for septic loosening after 2.1 years; however, the graft was well integrated and provided sufficient support for the revision cup. All the others had a good clinical and radiological result after an average of 11.4 years with an average Harris Hip Score of 97. The authors have found this an easy-to-use method, which can give an excellent, long-lasting result. It also provides important bone stock for possible subsequent revisions.;