Effect of the Hybrid Screw Insertion Technique Using Pedicle and Laminar Screws at the Upper Instrumented Vertebra for Preventing Proximal Junctional Kyphosis

Study DesignRetrospective comparative study.ObjectiveTo evaluate whether a hybrid screw insertion technique (one pedicle screw and one laminar screw) at the upper instrumented vertebra (UIV) preserves vertebral trabecular architecture and reduces the incidence of proximal junctional kyphosis (PJK) compared with conventional bilateral pedicle screw fixation in adult spinal deformity (ASD) surgery.MethodsFrom March 2023 to August 2024, 89 patients who underwent ASD surgery using the hybrid screw insertion technique and had a minimum follow-up of 12 months were retrospectively reviewed. The control group consisted of 78 patients who underwent ASD surgery using conventional UIV fixation, performed by the same surgeon during an 18-month period of identical duration immediately preceding the study period. The incidences of PJK and PJF within the first postoperative year were compared between the two groups.ResultsBaseline demographic characteristics and preoperative and postoperative spinopelvic parameters were comparable between the two groups, except for preoperative lumbar lordosis, which was greater in the hybrid screw group. During the first postoperative year, the incidence of PJK was lower in the hybrid screw group than in the control group (16.9% [15/89] vs. 35.9% [27/78], p = 0.005). No significant difference was observed in the incidence of PJF. Multivariate analysis identified hip bone mineral density, postoperative L1PA, and the use of the hybrid screw insertion technique as independent predictors of PJK.ConclusionsThe hybrid screw insertion technique may reduce the risk of PJK in ASD surgery by preserving vertebral trabecular architecture at the UIV compared with the conventional method.