Can Thoracolumbar Deformity Improve if Surgery Just for Lumbar Stenois Syndrome in Degenerative Thoracolumbar Kyphosis Patients ?

Background: Fusion across thoracolumbar spine or not for degenerative thoracolumbar kyphosis (DTLK) in lumbar stenois syndrome (LSS) remains controversial. The influencing factors for postoperative TLK in this group have not been determined yet. So the study was to explore whether DTLK could improve with only surgery for lumbar stenois syndrome LSS and identify influencing factors on postoperative TLK. Methods: : The study was performed from January 2016 to December 2018. 69 participants (25 male) diagnosed LSS with DTLK were enrolled and surgery was only for LSS. Radiological parameters included TLK, lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and osteoporosis. Clinical outcomes were visual analogue scale (VAS) and Oswestry disability index (ODI). According to lower instrumented vertebrae (LIV) on L5 or S1, inter-group comparisons were performed between LIV on L5 (L5 group) and S1 (S1 group). Results: : Demographics was well-matched between L5 and S1 group with a mean follow-up of 24.3±12.1 (m). TLK improved with a mean of 16.2±7.6 (°) (P <0.001). It was insignificant on radiological and clinical parameters between L5 and S1 groups except a larger PT in S1 group (P=0.046). VAS (P=0.787) and ODI (P=0.530) were both indifference between normal TLK and DTLK at last (P˃0.05). Postoperative TLK was affected by osteoporosis and SS, the latter was determined by PI and PT. Osteoporosis was the risk factor for TLK correction (P=0.001, OR=9.58). Conclusions: : DTLK get improved if suegery only performed for LSS. TLK and clinical outcomes are comparable between L5 and S1 groups. Severe osteoporosis can impede TLK correction.