"The protective buffer": Adequate L4-S1 lordosis restoration reduces the symptomatic conversion of radiographic ASD and long-term revision rates - A 5-year multicenter cohort study.

Authors

Chen Wang, Zhifeng Dong, Jing Jia, GuangYi Zhang, Xirong Fan, Kai Zhang, Wen Xue, Qilong Wang, Zeng Ping Wang, ShuanHu Lei

Published in

European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society. Jul 30, 2026. Epub Jul 30, 2026.

Abstract

Inadequate restoration of L4-S1 segmental lordosis (SL) is a recognized contributor to adjacent segment disease (ASD). However, evidence regarding its impact on long-term revision rates remains conflicting, primarily due to short follow-up periods that fail to capture the critical transition from radiographic degeneration to symptomatic disease.
To evaluate the 5-year impact of L4-S1 SL restoration on revision rates and to introduce the concept of "Symptomatic Conversion Rate" to quantify the clinical progression of ASD.
A multicenter, retrospective cohort study.
A total of 232 patients who underwent L4-S1 transforaminal lumbar interbody fusion (TLIF) with a minimum 5-year follow-up were included. The cohort was stratified into Adequate and Inadequate Restoration groups based on postoperative L4-S1 SL.
The primary endpoint was the 5-year revision surgery rate. Secondary endpoints included radiographic parameters (pelvic tilt [PT], pelvic incidence-lumbar lordosis [PI-LL] mismatch), implant failure rates, and patient-reported outcome measures (Oswestry Disability Index [ODI], Visual Analog Scale [VAS]). The "Symptomatic Conversion Rate" (the percentage of patients with radiographic ASD progressing to symptomatic ASD) was also assessed.
Clinical and radiographic data collected at a minimum of 5 years postoperatively were retrospectively analyzed. The cohorts were compared to assess the influence of L4-S1 SL restoration on long-term survivorship, functional recovery, and ASD progression.
Baseline demographics and PI were comparable between groups (P > 0.05). At the 5-year follow-up, the Inadequate Group exhibited significant pelvic retroversion (PT increased to 21.82° vs. 17.26° in the Adequate Group, P < 0.001). Although radiographic ASD was prevalent in both cohorts (58.1% vs. 38.1%), the Symptomatic Conversion Rate was markedly higher in the Inadequate Group (73.3% vs. 28.1%, P < 0.001). Consequently, the 5-year revision rate was significantly greater in the Inadequate Group (26.4% vs. 2.4%, P < 0.001). The Inadequate Group also demonstrated inferior ODI scores (28.5 vs. 14.2, P < 0.001) and an increased incidence of screw loosening.
Inadequate L4-S1 SL restoration is an independent risk factor for long-term revision surgery and implant failure following TLIF. Precise restoration provides a crucial "biomechanical buffer," preventing compensatory pelvic retroversion and significantly reducing the conversion of radiographic ASD into symptomatic disease. Achieving this protective buffer should be a primary surgical objective to maximize long-term construct survivorship.

PMID:
42530596
Bibliographic data and abstract were imported from PubMed on 30 Jul 2026.

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