Spine Clinical Fellow University at Buffalo Neurosurgery - UBNS University at Buffalo Neurosurgery Buffalo, NY, US
Introduction: Lumbar spine fusion is one of the most commonly performed spinal surgeries, and investigating common complications such as adjacent segment disease (ASD) is a high priority. To the authors' knowledge, there are no previous studies investigating the utility of the preoperative magnetic resonance imaging-based fatty infiltration index of the paravertebral musculature in predicting radiographic and surgical ASD after lumbar spine fusion. We aimed to investigate the predictive factors for radiographic and surgical ASD, focusing on the predictive potential of the fatty infiltration of the psoas and multifidus muscles (psoas/multifidus index).
Methods: A single-center retrospective analysis was conducted of all patients who underwent 1-3 level lumbar or lumbosacral interbody fusion for lumbar spine degenerative disease. Demographic data were collected, along with patient medical, and surgical data. Preoperative MRI was assessed in the included patients using the fatty infiltration of the psoas/multifidus index to identify whether radiographic ASD or surgical ASD could be predicted.
Results: A total of 117 patients were identified (mean age, 59.8 ± 12.4 years; women, 54.0%). Twenty- three (19.7%) patients developed radiographic ASD, and 16 (13.9%) developed surgical ASD. A lower fatty infiltration index was a significant predictor of radiographic ASD in univariate analysis (0.2 ± 0.15 vs 0.7 ± 0.2; P<.001) and multivariate analysis (odds ratio, 1.501; 95% CI, 1.353-1.663; P < .001). For surgical ASD, a significantly lower index was seen in univariate analysis (0.15 ± 0.17 vs 0.6 ± 0.2; P < .001) and served as an independent risk factor in multivariate analysis (odds ratio, 1.509; 95% CI,1.324-1.720; P<.001).
Conclusion : The fatty index of the psoas and multifidus muscle predicted the presence of ASD after lumbar fusions.