Study design: A age- and sex-matched case-control radiographic study.
Objective: To identify the predisposing factors of degenerative spondylolisthesis (DS).
Summary of background data: None of the radiologic methods for predicting the development of DS are very reliable or readily accessible. The methods commonly used are computed tomography or magnetic resonance imaging.
Methods: Data were gathered retrospectively on middle-aged women with degenerative lumbar spondylolisthesis.
Results: The most common slipped vertebra was L4 (63.64%) and the second was L5 (13.64%). Most parameters, including the disc height, body height, and angle measurements, for the case group tended to be lower than the control group, whereas the transverse process were larger than control group. The differences in disc height, lumbar index (LI), sacral inclination angle (SIA), sacral horizontal angle (SHA), and transverse process between the 2 groups were statistically significant (P < 0.05). Multivariate logistic regression analysis confirmed that anterior inferior disc height (DHIA) and LI were independent variables of predisposing factor to DS and both could explain a 50% variation of DS. Further analysis of the different levels of spondylolisthesis (L4 on L5 vs. L5 on S1 DS) revealed that there was a significant difference in the width of L5 transverse process in L4 on L5 spondylolisthesis (P = 0.03) but insignificant on disc height (P = 0.86).
Conclusion: There are 2 independent predictors of DS, decreased anterior disc height and increased lumbar index. The iliolumbar ligament also contributes to the stability of lumbosacral junction, especially in L5 on S1 DS.