2025 Volume 16 Issue 7 Pages 982-988
Introduction: The utility of sagittal flexible screws (SFS) for the prevention of PJK after surgery for adult spinal deformity (ASD) was evaluated.
Subjects and Methods: Patients who underwent cMIS using LLIF and PPS for ASD at our hospital after 2023 who were followed up for at least 12 months were included in this study. We evaluated the spinopelvic parameters, rod contour angle (RCA), pedicle screw angle (PSA), rod screw angle (RSA), PJK/PJF incidence, UIV/UIV-1 angle (UIVA), and the difference between UIVA in sitting and supine positions (UIVM) in the S group, which used SFS for UIV, and the NS group, which did not use SFS for UIV. UIVA was defined as the angle between the UIV cephalic endplate and the UIV-1 caudal endplate, RCA was defined as the posterior curvature angle of the rod from the UIV to L1, and PSA was defined as the angle between the cephalic endplate of the UIV and the screw.
The RSA was defined as the angle between the rod and screw in the UIV.
Results: No significant differences were observed between the two groups in terms of patient background, ODI, or spinopelvic parameters. Additionally, no significant differences were observed in the RCA, PSA, and RSA. Although no significant differences were present in postoperative UIVA, UIVM was 2.2° in the S group and 0.5° in the NS group, showing a significant difference. No significant difference was observed in the incidence of PJK/PJF or screw loosening between the two groups.
Conclusion: The results of this study indicate that SFS can tolerate slight movement of the UIV after surgery, and that a gradual transition from the fixed vertebra to the non-fixed vertebra may be achieved. Although no significant difference was observed in the incidence of PJK and screw loosening, the results suggest that this gradual transition effect from the fixed vertebra to the non-fixed vertebra may be useful for preventing degeneration at the adjacent disc level in the long term.
