A method of planning a hip arthroplasty for a subject is described the method comprising: receiving at least one image of the subject, wherein the at one least image is substantially acquired from the sagittal plane when the subject is standing; calculating at least one spinopelvic metric from the at least one image; and based on the calculated spinopelvic metrics, calculating a hip arthroplasty risk characteristic of the subject. Also described are a method of determining a range of acetabular cup orientation angles for an acetabular cup implant for a subject is also described and a computer-implemented method of determining a range of orientation angles for an acetabular cup implant for a subject.