Body position alters kyphosis angle: comparison of supine MRI and prone full-length spine CT scout view in osteoporotic thoracolumbar fractures.

Objective: To compare the degree of kyphosis among patients with old thoracolumbar fracture kyphosis (OTFK) in various positions and to assess kyphosis flexibility. Methods: A total of 32 patients with OTFK who met the inclusion criteria were retrospectively included between February 2017 and August 2022. The cohort consisted of 4 males and 28 females with a mean age of 66.47 years (range, 55-88 years). All patients underwent preoperative standing full-length spine x-ray, prone full-length spine CT scout view (FLS-CT), and supine MRI. Among them, 29 patients had single-segment fractures and 3 had double-segment fractures. The local kyphosis Cobb angle (LKCA) was measured on all imaging modalities. The LKCA measured on standing x-ray and FLS-CT were recorded as LKCA Results: The mean standing LKCA was 39.58 ± 9.00°. The LKCA measured on prone FLS-CT was 29.61 ± 6.96°. On supine MRI, the LKCA values were 28.34 ± 6.37° (LKCA Conclusion: Kyphosis severity was significantly reduced in the preoperative recumbent position in patients with OTFK. Prone FLS-CT and supine MRI provided clinically comparable estimates of positional kyphosis correction, suggesting that both modalities may be useful for preoperative assessment of kyphosis flexibility in OTFK.