eng Science and Education Publishing American Journal of Clinical Medicine Research 2328-403X 2014-06-15 2 3 57 60 10.12691/ajcmr-2-3-2 AJCMR2014232 article Norio Imai imainorio2001@yahoo.co.jp 1 Dai Miyasaka 1 Yoji Horigome 1 Hayato Suzuki 1 Ryota Takubo 1 Naoto Endo 1 Department of Orthopaedic Surgery, Niigata University Medical and Dental Hospital, Niigata, Japan 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. http://pubs.sciepub.com/ajcmr/2/3/2/ajcmr-2-3-2.pdf anterior pelvic plane lateral radiograph total hip arthroplasty sacral slope pelvic flexion angle accuracy