Case Series on the Effectiveness of Preoperative Radiological Templating on Acetabular Cup Orientation in Total Hip Arthroplasty of Developmental Dysplasia of the Hip

Total hip arthroplasty becomes the challenging treatment in cases of neglected developmental dysplasia of the hip but requires elaborate preoperative planning, especially for the restoration of the normal hip center, correction of shortening, and achieve normal biomechanics to avoid limb and early failures. To determine the morphological changes resulting from the dysplasia, the anatomic acetabular position, the height of the femur head dislocation and the combined anteversion must all be established. Preoperative planning was done using 100% zoom digital X-rays of the pelvis with both hips in 15° of internal rotation. This included identification of true acetabulum and centre of hip rotation using Ranawat's triangle. Templating was done to determine the position of acetabulum and size of the cup and required length of subtrochanteric osteotomy. The length of subtrochantric osteotomy was determined so that it would not lengthen the leg more than 3 cm to prevent sciatic nerve stretching. The postoperative X-rays were compared with the template of X-rays for the effectiveness of preoperative planning in restoring the near-normal biomechanics of the hip joint.