Study design: A retrospective study.
Objective: The aim of this study was to identify the relationships between radiological findings and the presence of stooping in lumbar degenerative kyphosis (LDK).
Summary of background data: Many studies have addressed fixed sagittal imbalances and surgical treatments. However, information regarding the relationship between radiological findings and stooping in LDK is sparse.
Methods: The study included 73 patients with LDK and 44 with normal lumbar lordosis. Of those with LDK, 63 patients exhibited stooping (group 1) and 10 did not (group 2). Of those with 44 normal lumbar lordosis, 13 patients exhibited stooping (group 3) and 31 patients did not (group 4). Radiographic parameters such as sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), thoracic kyphosis (TK), lumbar lordosis (LL), horizontal distance between C7 plumb line and the posterosuperior corner of the sacrum (C7PL), sacrofemoral distance (SFD), C7PL/SFD ratio (C7/SFD), spinosacral angle (SSA), spinopelvic angle (SPA), C2-C7 lordosis (CL), C2-C7 sagittal vertical axis (C2-C7 SVA), T1 slope, and T1 slope minus C2-C7 lordosis (TS-CL) were analyzed.
Results: Significant differences were observed in TK, LL, C7PL, SFD, C7/SFD, PT, SS, SSA, SPA, C2-C7 SVA, and TS-CL between LDK and normal lumbar lordosis, but no significant intergroup difference was observed in PI, CL, or T1 slope. These results showed that groups 1 and 3 had higher C7PL, C7/SFD, PT, and CL values than groups 2 and 4. Logistic regression analysis revealed that C7/SFD and CL could significantly predict stooping in LDK.
Conclusion: C7/SFD and CL predict the presence of stooping in LDK. Furthermore, patients with LDK with compensatory mechanisms to maintain sagittal balance have low C7PL values, that is, C7/SFD < 0.5 and high PT and CL on upright whole spine lateral radiography.
Level of evidence: 3.