## 4 Discussion  
During lumbar surgeries--oblique lumbar inter-body fusion and direct lumbar inter-body fusion to name two--the patient must be positioned in a lateral decubitus position. Bending the AHCFOT to a convex 20\({}^{\circ}\) flexion makes it easier to open and access the desired disc space to perform lumbar interbody fusion [9]. In spite of providing flexibility in terms of patient position, the efficacy of table bending on sagittal alignment remains unclear.  
In our study we have demonstrated the efficacy of 20\({}^{\circ}\) convex and concave AHCFOT bending on lumbar sagittal alignment. We found that the lordosis of the lumbar spine on AHCFOT in neutral position is 45.2 \(\pm\) 11.0\({}^{\circ}\). Average lumbar lordosis achieved in 20\({}^{\circ}\) convex bending (lumbar flexion) is 35.9 \(\pm\) 10.8\({}^{\circ}\) and in 20\({}^{\circ}\) concave bending (lumbar extension) is 52.0 \(\pm\) 10.7\({}^{\circ}\). This elucidates that a significant corrective range of lumbar sagittal motion can be acquired by positioning the patients over a AHCFOT.  
We found the 20\({}^{\circ}\) convex and 20\({}^{\circ}\) concave table bending efficacy to be 46.5% and 33.9%, respectively. These results provide better helps to predict lumbar lordosis. A previous AHCFOT study has shown a significant difference in coronal alignment between men and women, possibly due to high body mass index, joint laxity, muscle strength [9]. However, there was not a significant difference in sagittal alignment amongst men and women in our study. This is most likely due to the bending forces acting on coronal versus sagittal alignment on the facet joints.  
In patients presenting with spondylolisthesis, during spine surgeries such as posterior lumbar inter-body fusion (PLIF), transforminal lumbar inter-body fusion (TLIF), efficacy data of AHCFOT bending could be useful to achieve adequate lumbar lordosis [10]. No difference was found while performing short segment PLIF with different operating tables and patient positioning [10]. But in their study, they used a non-hinged conventional operating table. It is imperative that one should keep in mind that segmental loss of lordosis, at the spine levels being operated, in short segment fusions, may lead to compensatory hyper-lordosis at the adjacent levels and a possible accelerated degeneration [11]. Still, the long-term outcomes of positioning the patient on AHCFOT and lumbar lordosis achieved intraoperatively are not reported. In elderly patients with adult spinal deformity, deformity correction surgery has helped in relieving pain and improving functions [12]. For surgical management to correct the deformity and create adequate lumbar lordosis, one has to do all anterior and posterior release surgery, in situ rod bending, and preoperative patient positioning depending on severity of deformity [13,14]. According to our results, the surgeons can create an additional 6.8\({}^{\circ}\) lumbar lordosis by table bending alone.  
Figure 6: 72-year-old woman, adult spinal deformity, T10 pelvis fixation. (**A**): Preoperative anteroposterior radiogram, (**B**): Preoperative lateral radiogram (sagittal vertical axis 83 mm, lumbar lordosis 7 degrees, pelvic tilt 39 degrees), (**C**): Preoperative CT, (**D**): Postoperative anteroposterior radiogram, (**E**): Postoperative anteroposterior radiogram (sagittal vertical axis 0 mm, lumbar lordosis 46 degrees, pelvic tilt 24 degrees), (**F**): Postoperative CT.  
Our research does have a few limitations, one of them being a small cohort size. A larger cohort size would lead to more accurate and predictive results. Also, patients enrolled in this study were average elderly patients. Because of that, they had more degenerative changes, so that little arc of motion on the flexible table has been achieved. We also did not consider the disc degeneration, analysis of segmental lordosis, whether the foraminal area changed or not. In this study, clinical relevance was not evaluated.