The relationship between the orientation of the lateral decubitus position for spinal anesthesia and positioning pain in patients with a femoral neck fracture: randomized non-inferiority trial

BACKGROUND: To date, no clinical studies have investigated the relationship between positioning pain and orientation of the lateral decubitus position for hip fracture surgery. The aim of the present study was to test the hypothesis that performing spinal anesthesia in the lateral decubitus position with the fracture side up or down does not affect positioning pain in patients with a femoral neck fracture. METHODS: This single-center, prospective, randomized non-inferiority trial examined 78 patients who received surgery for a femoral neck fracture under spinal anesthesia. By performing spinal anesthesia in the left lateral decubitus position in all patients, the positioning of the fracture up or down was randomized. Pain score during spinal anesthesia was evaluated objectively (0, calm; 1, facial grimacing; 2, moaning; 3, screaming; or 4, unable to proceed because of restlessness or agitation). RESULTS: The data from 66 patients (fracture side down [n = 35] and up [n = 31]) were analyzed. There were no significant differences between the fracture side down and fracture side up groups regarding the percentage of patients who were assessed to have intense pain (score ≥ 3) when changing position from the supine to lateral position (13/35 [37%] vs 12/31 [39%]; 95% confidence interval [95% CI] for the difference of the percentage of patients of intense pain between the groups − 25.0 to 2.2; p = 1.000). CONCLUSIONS: There were no significant differences in the percentage of patients experiencing severe pain between the two groups. The 95% CI exceeded the preliminarily set a margin of inferiority of 20%; thus, the present study could not demonstrate the non-inferiority of the fractured side down group in terms of pain score.