Vol.:(0123456789) 1 3 Spine Deformity https://doi.org/10.1007/s43390-019-00005-3 ORIGINAL ARTICLE Ideal sagittal profle restoration and ideal lumbar apex positioning play an important role in postoperative mechanical complications after a lumbar PSO Javier Pizones 1  · Francisco Javier Sánchez Perez‑Grueso 1  · Lucía Moreno‑Manzanaro 1  · Alba Vila‑Casademunt 2  · Louis Boissiere 3  · Caglar Yilgor 4  · Nicomedes Fernández‑Baíllo 1  · José Miguel Sánchez‑Márquez 1  · Gloria Talavera 1  · Frank Kleinstück 5  · Emre R. Acaroglu 6  · Ahmet Alanay 4  · Ferran Pellisé 7  · Ibrahim Obeid 3  · the ESSG (European Spine Study Group) 2 Received: 13 July 2019 / Accepted: 13 October 2019 © Scoliosis Research Society 2020 Abstract Study design Retrospective analysis of prospectively collected data. Objective To determine the infuence of postoperative ideal lordosis distribution and ideal sagittal harmony on mechanical complications in patients undergoing one-level lumbar pedicle subtraction osteotomy (L-PSO). Summary of background data Many variables have been associated with mechanical complications after L-PSO. However, the impact of restoring the ideal infexion point, lumbar apex, and sagittal shape is still underexplored. Methods Analyzed risk factors were: age and patient-related variables, PSO level, interbody cages, rod material/diameter, number of rods, upper instrumented vertebra, lower instrumented vertebra, PI-LL mismatch, global tilt (GT), postoperative level of lumbar apex (LApex), postoperative level of infexion point (InfxP), and postoperative type of Roussouly sagittal profle (R-type). These last variables were compared to ideal (based on pelvic incidence). Univariate and multivariate analyses were performed to identify risks for mechanical complications with a minimum 2-year follow-up. Results A total of 87 patients were included. Mean follow-up was 4.5 ± 1.7 years. 40.2% of the patients sufered postopera- tive mechanical complications (7 PJK, 4 PJF, 18 pseudoarthrosis/rod breakage, 6 screw pullout). Mean time for complica- tions was 584 ± 416 days from surgery. Univariate analysis showed that age (63 vs 57 years; P = 0.04), BMI (28.1 vs 25.9; P = 0.024), preoperative-GT (50.7° vs 38.7°; P < 0.001), postoperative-GT (28.9° vs 23.4°; P = 0.018), postoperative LApex location mismatched from ideal (77.8% vs 22.2%; P = 0.036), and postoperative R-type mismatched from ideal (67.6% vs 22.6%; P < 0.001) were signifcantly related to mechanical complications. The independent factors selected by multivariate analysis were: postoperative R-type mismatched from ideal OR 11.3 (95% CI 3.9–32.6; P < 0.001), age OR 1.05 (95% CI 1–1.1; P = 0.03), and LApex matching OR 0.5 (95% CI 0.27–0.97; P = 0.04). The further the LApex was from its ideal posi- tion, the higher the risk of mechanical complications (P = 0.036). Conclusions Over other multiple suspected risk factors, proper lumbar apex position and ideal sagittal shape restoration played an important role in postoperative mechanical complications after L-PSO. Level of evidence III. Keywords Pedicle subtraction osteotomy · Sagittal alignment · Roussouly sagittal profle · Lumbar distribution · Mechanical complications Introduction A pedicle subtraction osteotomy at the lumbar spine (L-PSO) can be performed to correct a symptomatic anterior malalignment in a stif spine [1, 2]. The surgery is techni- cally demanding [3], and aside from the inherent intraopera- tive complications that may occur [4], around 40% rate of * Javier Pizones javierpizones@gmail.com Extended author information available on the last page of the article