The precision and usefulness of preoperative planning for cemented and hybrid primary total hip arthroplasty.

We evaluated the utility of a preoperative planning technique with a review of preoperative radiographs, templates, plans, charts and 6-week postoperative radiographs of 139 total hip arthroplasties (THAs) (116 cemented and 23 hybrid) to determine size, orientation of the implants, and cement column mantle, location of the planned and achieved center of rotation, and limb-length discrepancy. The acetabular component size was predicted exactly in 116 hips (83%) (within +/-1 size in 138 hips [99%]); the femoral component size was predicted exactly in 108 hips (78%) (within +/-1 size in 138 [99%]). In 75 arthroplasties (45%), the center of rotation was within 2 mm of horizontal and vertical distance from the plan, and in 127 (91%) arthroplasties, it was within 4 mm. The inclination of the cup averaged 44 degrees (range, 30 degrees -58 degrees ). The stem was in a neutral alignment in 122 hips (88%), varus in 11 hips (8%), and in 2 degrees of valgus in 6 hips (4%). In 103 arthroplasties with a normal contralateral hip or a THA, the average limb-length discrepancy was 1.71 mm. Preoperative planning is useful to predict the implant size, position, and alignment, to restore the center of rotation, and to equalize limb length.