Abstract: Objective To explore the changes of anterior and posterior spinal-pelvic sagittal parameters in patients with lumbar spinal stenosis(LSS)who received single-segment transforaminal lumbar interbody fusion(TLIF). Methods The clinical data of 102 patients with LSS who underwent single-segment TLIF during Jan. 2010 and Oct. 2016 were retrospectively analyzed. The patients aged 61-85 years, average(66.4±4.8)years. The preoperative and 2-year postoperative sagittal parameters were determined, including lumbar lordosis(LL), thoracic kyphosis(TK), thoracolumbar junctional angle(TLJA), pelvic incidence(PI), pelvic tilt(PT), sacral slope(SS), sagittal vertical axis(SVA)and mismatch between pelvic incidence and lumbar lordosis(PI-LL). SVA≥40 mm was defined as sagittal imbalance. Based on this, the patients were divided into the balance group(n=65, SVA<40 mm)and imbalance group (n=37, SVA≥40 mm)before operation. After operation, imbalance group were subdivided into the restoration group (n=23, 山 东 大 学 学 报 (医 学 版)57卷5期 -贾军,等.腰椎管狭窄单节段经椎间孔椎体间融合手术前后矢状位参数值的变化 \=-SVA<40 mm)and non-restoration group (n=14, SVA≥40 mm). Visual Analog Scale(VAS)score, Japanese Orthopaedic Association(JOA)score and Oswestry Disability Index(ODI)were used to evaluate preoperative and postoperative clinical outcomes. Results The incidence of preoperative sagittal imbalance was 36.3%. Compared with the balance group, the imbalance group had smaller LL and TK, larger PI-LL and PT, and poorer VAS score, JOA score and ODI(all P<0.05). After operation, the imbalance group had greater changes in SVA, LL, TK and PI-LL than the balance group (P<0.05). After 2 years of follow-up, the sagittal balance was restored in 23 patients(62.2%). The 14 patients who failed to restore the balance had preoperative SVA>90 mm, and PI-LL>20°. Compared with the restoration group, the non-restoration group had larger preoperative SVA and PI-LL, but smaller LL and TK(all P<0.05), while there were no differences in postoperative VAS, JOA and ODI between the two groups(all P>0.05). Conclusion Most sagittal imbalance is related to patients’ protective position, and single-segment TLIF can effectively improve sagittal imbalance. In addition, there is no correlation between postoperative sagittal imbalance and short-term clinical outcome. Therefore, preoperative sagittal imbalance alone may not be used as the indication for long-segment orthopedic surgery.

Key words: Lumbar spinal stenosis, Spine, Pelvis, Transforaminal lumbar interbody fusion, Sagittal view, Imbalance