L5 incidence: an important parameter for spinopelvic balance evaluation in high-grade spondylolisthesis

This paper describes L5I, which is a positional parameter in HGSPL. L5 incidence is a simple and reliable measure in the preoperative setting in HGSPL. Its correlation with spinal sagittal parameters (especially PT and LL) is strong and was found to be better than Dub-LSK. There is also a good correlation between L5I and HGSPL pelvic parameters (slip percentage and lumbosacral kyphosis). We recommend its use for evaluation of surgical correction and recommend the value of 60° as cutoff value to define spinopelvic balance in HGSPL.