Lumbo-femoral angle: a novel sagittal parameter related to quality of life in patients with adult scoliosis

Purpose PT and PI-LL sometimes offer limited utility in daily practice when evaluating QOL, especially in outpatient clinics with limited time and equipment facility. This study proposes a novel spino-pelvic parameter, lumbo-femoral angle (LFA). The purpose of this study is to analyze the correlation between LFA and HRQOL in adult scoliosis patients. Methods A cohort of 100 asymptomatic adult volunteers and 50 patients with adult scoliosis were prospectively recruited. The following sagittal parameters including thoracic kyphosis (TK), LL, LFA, PI, PT and sacral slope (SS) were measured on the long-cassette standing upright lateral radiographs. Health-related QOL (HRQOL) measures included the VAS, ODI and SF-36 instruments for patients with adult scoliosis. Results LFA, the novel regional lumbo-sacral parameter, averaged 0.68° ± 4.5° in normal adults with the 95 % CI value of −7° to 7°. Similar intra- and inter-observer intraclass correlations and less measurement time were observed in LFA compared to PI-LL indicating that it is easy to quantitatively evaluate the regional alignment directly from X-ray films. Although LFA in patients with adult scoliosis was found to be significantly larger (11.8° ± 8.7° vs. 0.68° ± 4.5°, p