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A simple and accurate method for determining leg length in primary total hip arthroplasty.

Reconstruction of appropriate leg length is an important part of soft-tissue balance in total hip arthroplasty (THA). Leg length discrepancy (LLD) is one of the more common reasons for litigation after otherwise successful THA. The purpose of the study reported here was to analyze the accuracy of using preoperative templating and intraoperative referencing of the well leg to determine postoperative leg length in unilateral primary THA. Seven-hundred primary THAs performed at an institution by 3 surgeons were randomly selected from a computerized database. Cases with significant bilateral disease, congenital dysplasia, acute fracture, or previous surgery or without complete preoperative and postoperative radiographs were excluded. Three reviewers used a standardized method to measure preoperative and postoperative LLD. Included in the review were 410 THAs. Mean postoperative LLD was 3.9 mm lengthening (SD, 7.5 mm). In 20 THAs (4.9%), lengthening was more than 15 mm. Lengthening was more than 20 mm (maximum, 22 mm) in 4 THAs (1%). Of the 20 THAs with LLD of more than 15 mm, 14 involved hips that were longer preoperatively. Thirteen of these hips were reconstructed to within 10 mm of preoperative LLD. Only 2 patients with radiographic LLD of more than 15 mm perceived LLD. There were no differences in gender, height, weight, or body mass index. This method of preoperative templating and referencing the well leg intraoperatively is an inexpensive, reliable, and accurate method for determining leg length in primary THA and has few significant radiographic or clinical outliers.