[Minimally invasive lateral lumbar interbody fusion significantly improves the sagittal balance for adult degenerative scoliosis]

Objectives: To evaluate the effect of minimally invasive lateral lumbar interbody fusion (LLIF/OLIF) on the sagittal balance of adult degenerative scoliosis. Methods: From January 2014 to June 2017, a total of 23 patients with degenerative scoliosis underwent staged minimally invasive surgery in Shanghai Ruijin Hospital. All patients were implanted with LLIF or OLIF cage from the lateral approach first, and was followed by the posterior percutaneous pedicle screw fixation or pedicle screw fixation via Wiltse approach. If the sagittal deformity correction was not satisfactory after the first surgery, a posterior osteotomy can be performed during the second stage operation. A biplanar X-ray of the whole spine was taken with the EOS imaging system before and after surgery. The EOS software was used to measure and evaluate the patient's sagittal balance parameters including pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), the sagittal vertical axis (SVA) and the coronal Cobb angle. The visual analogue scale (VAS) score for low back pain, the Oswestry Disability Index (ODI) score were evaluated before and after surgery. Paired t test or repeated measures ANOVA was used to compare the data before and after surgery. Results: There were 6 males and 17 females with a mean age of (72±4) years (62-79 years). Nine patients were treated with LLIF and 14 patients with OLIF. Sixteen cases were implanted with three cages, five with two cages and two with four cages. The mean follow-up period was 24.2 months (15-42 months). After the first operation, the Cobb angle of the patient was significantly improved (18°±7° vs 33°±8°, t=13.2, P<0.01). All the parameters for sagittal balance, including PI-LL (20°±8° vs 31°±8(o)), SVA ((5.3±2.0) cm vs (8.2±3.5) cm), PT (16°±6° vs 23°±4°) were all significantly improved as well (t=6.8, 4.5, 9.0, ALL P<0.01). At the last follow-up, the VAS score of low back pain (3.4±1.1 vs 6.3±1.0) and ODI scores (27.3%±3.0% vs 47.1%±5.9%) were also significantly improved (t=11.3, 17.8, both P<0.01). No major complications occurred in this group. Conclusions: Minimally invasive LLIF/OLIF can significantly improve the coronal and sagittal balance of adult degenerative scoliosis. Staged minimally invasive surgery can significantly alleviate pain and improve function in these patients.