Measurement of Spinopelvic Parameters on Standing Lateral Lumbar Radiographs: Validity and Reliability

Abstract

STUDY DESIGN: This was a radiographic validity and reliability study. OBJECTIVE: We assessed the validity and reliability of measurements made on standing lateral lumbar radiographs, compared with lateral whole-spine radiographs, for evaluating spinopelvic parameters and lumbar lordosis (LL). SUMMARY OF BACKGROUND DATA: A lateral whole-spine radiograph is the gold standard image for measurement of spinopelvic parameters. However, little evidence is available on the reliability of measurements made on such radiograph. A standing lateral lumbar radiograph is routinely obtained from patients with back pain and/or a disability. This image can include upper end plate of L1 vertebra, sacral dome and both femoral heads. Thus, this radiograph can be used for evaluation of spinopelvic parameters. MATERIALS AND METHODS: We randomly selected 50 sets of digital radiographs (standing lateral lumbar and lateral whole-spine radiographs) from our database. Three experienced spinal surgeons independently measured LL, pelvic incidence, pelvic tilt, and sacral slope on all images. A paired t test and Pearson correlation was used to analyze the validity of the lateral lumbar radiograph. Interobserver and intraobserver reliabilities were assessed by intraclass correlation coefficient. RESULTS: Thee spinopelvic parameters and LL measured on lateral lumbar radiographs were similar to those measured on lateral whole-spine radiographs (All P-values >0.05, Pearson correlation coefficients, 0.807-0.969). The intraobserver and interobserver reproducibilities of both measurement types were good-to-excellent. CONCLUSIONS: Spinopelvic parameters and LL values measured on lateral lumbar radiographs were reproducibly similar to those measured on lateral whole-spine radiographs. Use of a standing lateral lumbar radiograph is reasonable when spinopelvic parameters and LL are to be measured.