Science and Education Publishing American Journal of Clinical Medicine Research 2328-403X 2 3 2014 06 15 Are Measurements of Sacral Slopes Reliable? 57 60 EN Norio Imai Department of Orthopaedic Surgery, Niigata University Medical and Dental Hospital, Niigata, Japan Dai Miyasaka Yoji Horigome Hayato Suzuki Ryota Takubo Naoto Endo AJCMR2014232 10.12691/ajcmr-2-3-2 2014 05 26 2014 06 12 2014 06 15 Background: Malpositioning during total hip arthroplasty may cause dislocation, pain, and other complications. To evaluate the potential of sacral slope (SS) as a reliable parameter of pelvic flexion. Methods: We developed a model of pelvic flexion to determine the intraobserver and interobserver variability and reliability of SS measurements by lateral radiography by three independent observers. Results: Measurement error was 1.2 and the intraobserver reliability was moderate to substantial (Interclass correlation coefficient: 0.31 to 0.66). Based on the Spearman-Brown formula, the measurement is reliable if it is done at least seven times by two observers, and four times by three observers. Conclusions: The data suggest that measurement of SS of pelvic flexion is a clinically useful parameter for the optimization of THA conditions.