Supine Imaging Is a Superior Predictor of Long-Term Alignment Following Adult Spinal Deformity Surgery

Abstract

Study Design: Retrospective cohort study. Objective: To investigate correlations between preoperative supine imaging and postoperative alignment. Methods: A retrospective review was conducted of a single-institution database of patients with adult spinal deformity (ASD). Patients were stratified by fusion location in the lumbar or thoracic spine. Outcomes of interest were postoperative lumbar lordosis (LL) and thoracic kyphosis (TK). Sagittal alignment parameters were compared and correlation analyses were performed. Multilinear stepwise regression was conducted to identify independent predictors of postoperative LL or TK. Regression analyses were repeated within the lumbar and thoracic fusion cohorts. Results: A total of 99 patients were included (mean age 63.2 years, 83.1% female, mean body mass index 27.3 kg/m2). Scoliosis Research Society classification demonstrated moderate to severe sagittal and/or coronal deformity (pelvic tile modifier, 18.2% ++; sagittal vertical axis, 27.3% ++, pelvic incidence minus lumbar lordosis mismatch, 29.3% ++, SRS type, 29.3% N type curve and 68.7% L or D type curve). A total of 73 patients (73.7%) underwent lumbar fusion and 50 (50.5%) underwent thoracic fusion. Correlation analyses demonstrated a significant association between pre- and postoperative LL and TK. Multilinear regression demonstrated that LL supine and pelvic incidence were significant predictors of postoperative LL ( r 2 = 0.568, P < .001). LL supine, TK supine, and age were significant predictors of postoperative TK ( r 2 = 0.490, P < .001). Conclusion: Preoperative supine films are superior to standing in predicting postoperative alignment at 1-year follow-up. Anticipation of undesired alignment changes through supine imaging may be useful in mitigating the risk of iatrogenic malalignment.

L1 slope: an overlooked spinal parameter

“…Therefore, the mean L1S, LL, and SS values reported for this group were very close to that of healthy subjects and can be accepted as an asymptomatic group. On the other hand, we thought that evaluation of spinopelvic parameters in supine position strengthened our study, because the importance of supine imaging tools has been increasing for several reasons [26][27][28]. First, the correlation between the spinopelvic parameters are strongest in the supine position and lumbosacral sagittal alingment in the supine position is appromixately equal to that in the prone position which is actually intraoperative position, so supine images can be helpful for the surgical planing [26].…”

“…First, the correlation between the spinopelvic parameters are strongest in the supine position and lumbosacral sagittal alingment in the supine position is appromixately equal to that in the prone position which is actually intraoperative position, so supine images can be helpful for the surgical planing [ 26 ]. Second, the difference between LL values measured in supine and standing position was found correlated with postoperative outcome in the patients with adult spinal deformity [ 27 , 28 ]. We believe that supine imaging will be utilized more commonly in the future for the diagnosis and the treatment of spinal disease.…”

Correlation between supine flexibility and postoperative correction in adolescent idiopathic scoliosis

“…However, Cheung et al reported that there was a significant difference between the fulcrum bending Cobb (28°) and postoperative Cobb angles at 1 month (15°) and 2 years after surgery (16°) [ 13 ]. Elysee et al investigated the correlation between preoperative supine imaging and postoperative alignment in adult spinal deformity (ASD) rather than AIS and reported that the difference between the supine and preoperative Cobb angles was 15.1° [ 27 ]. In our study, the mean difference between the supine and postoperative Cobb angles was 21.2° for the thoracic curve and 21.8° for the lumbar curve.…”

How Does Gravity Influence the Distribution of Lordosis in Patients With Sagittal Malalignment?

“… 29 Karikari et al 9 note that “stiff lumbar spines,” or those that have a <33% change in LL between the supine and standing position, are more likely to require a three-column osteotomy to achieve satisfactory deformity correction. Elysee et al 20 in their retrospective analysis of 99 patients with severe sagittal deformity determined that supine LL and pelvic incidence were the only significant predictors of post-operative LL. The authors also found that standing pre-operative lumbar lordosis poorly correlated with post-operative result.…”

“…To this end, we have found that supine imaging correlates with intraoperative decision-making as it is more reflective of prone positioning 19 and is superior to standing imaging in the prediction of long-term post-operative lumbar lordosis and thoracic kyphosis. 20 We hypothesized that understanding regional lumbar flexibility by comparing standing and supine radiographs can help identify regions of the lumbar spine that most significantly contribute to PI–LL mismatch. Such knowledge can dictate the need for, extended proximal fusion constructs in order to avoid proximal residual deformity and adjacent segment disease (ASD).…”