Objective:

To assess the effect that correction of lower lumbar lordosis (3L) has on global spine realignment due to the key role of 3L for scoliosis surgery in patients with degenerative lumbar scoliosis (DLS).

Methods:

This study is a retrospective review performed between June 2018 and January 2020, including consecutive patients with DLS. Only patients age ≥ 45 years who had already undergone a selective root block operation and had the procedure of long-fusion extending to pelvis and posterior lumbar interbody fusion (PLIF) at lower lumbar spine (L₄ -S₁ ) were retained for analysis. Spinopelvic parameters measured included thoracic kyphosis (TK), lumbar lordosis (LL), 3L, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), T₁ pelvic angle (TPA), and sagittal vertical axis (SVA) at pre-operation and the third month follow-up. The mismatch (PI-LL) was calculated subsequently. Pearson correlation and linear regression analysis were performed to explore the association of the changes in global spinopelvic parameters with 3L correction.

Results:

Thirty-nine patients (five males, 34 females) with the average age of 63.84 years (SD 7.53; range, 45-75 years) at the time of surgery were identified. All patients had the surgical procedure of long-fusion (≥4 vertebras) with PLIF at lower lumbar spine between L₄ and S₁ spine. Lower instrumented vertebras (LIV) fused to pelvis (S₁ , 14; S₂ , 18; ilium, 7) were operated in all patients. Seventeen patients were with upper instrumented vertebras (UIV) at thoracolumbar spine (L₂ -T₁₁ ), and 22 patients at thoracic spine (T10 and above). The median of instrumented segments was 10 (5-14). 3L significantly increased (P = 0.02) after surgical treatment by mean change of 4.21° (range, -19.7° to +22.2°). Perioperatively, all spinopelvic parameters regarding to TK, LL, SS, PT, TPA, SVA, and mismatch (PI-LL) had significant changes (P < 0.001). The change in 3L correlated significantly with the changes in spinopelvic parameters (r = 0.772 for LL, -0.589 for SVA, -0.439 for TPA, and -0.428 for PI-LL). After linear regression analysis, the formulas were obtained: d-LL = 14.977 + 0.636 × d-3L, (R² = 0.596); d-(PI-LL) = 16.575 + 0.62 × d-3L, (R² = 0.183); d-TPA = -7.284 to 0.358 × d-3L, (R² = 0.193); d-SVA = -30.556-2.639 × d-3L (R² = 0.347).

Conclusions:

Correction in lower lumbar lordosis, following the surgical procedure of long-fusion with PLIF at lower lumbar spine, could result in significant changes in full-spine parameters. The significant association of changes in each of global spine parameter with the correction of 3L perioperatively could provide important information for surgeons to make a surgical plan for spinal correction.