We describe a method for planning total hip arthroplasty (THA) in patients with a displaced femoral neck fracture based on a simple CT scan protocol of the contralateral hip. This protocol was used on 22 consecutive patients during the inclusion period, followed by reconstruction and 2D templating to predict the implant size and positioning. The exact planned size was achieved in 21/22 (95%) cups, 14/22 (64%) femoral stems and 14/22 (64%) femoral heads. There were no intra- or postoperative fractures. After surgery in which this planning method had been applied, the differences in length and lateral offset were less than 5 mm on average relative to the opposite side (mean postoperative leg length difference of −2 mm (−8 to +3 mm) and lateralization of −4 mm (−14 to +3 mm)). While this technique exposes the patient to additional radiation, it does not require any specific devices or surgical approach and could be used in most hospitals.

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