Total hip arthroplasty in the presence of acetabular non-union can be demanding. The irregular anatomy, the defect, and the presence of fibrous and necrotic tissue can hamper insertion of the acetabular component. We present a case of total hip arthroplasty in a patient with post-traumatic necrosis of the femoral head and non-union of the acetabulum and follow-up one year after the operation. Following accurate preoperative planning, removal of the pseudarthrosis material, and the use of the femoral head as an autograft, it was possible to insert the acetabular cup satisfactorily in a single-stage procedure.