Extreme lateral interbody fusion (XLIF): A single-center clinical and radiological follow-up study of 20 patients.

Extreme lateral interbody fusion (XLIF) is an alternative to standard posterior approaches for achieving fusion in the lumbar spine. It allows exposure of the lateral aspect of the lumbar disc through a lateral approach with the possibility to insert a wide footprint interbody cage as a stand-alone procedure or associated with a uni- or bilateral percutaneous fixation. This is a retrospective series of 20 consecutive patients operated with a XLIF procedure from 2014 to 2015. N=10 women and N=10 men with a mean age of 67.5years (range 37.9-81.2) were included in the study. N=18 patients have been operated at one level, while N=2 patients underwent a double-level XLIF. The index levels were: L2-L3 in 2, L3-L4 in 7, L4-L5 in 9 and L3-L5 in 2 patients, respectively. The mean clinico-radiological follow-up was 9.8months (range 2.5-16.6). The clinical outcome was assessed with the Oswestry Disability Index (ODI), Euro-Qol (EQ)-5D, visual analogue scale (VAS) and EQ-5D index scores. Preoperative, postoperative and follow-up sagittal balance was assessed by EOS full spine X-ray. Furthermore, presence or absence of fusion was assessed by thin cuts CT scan at the end of the follow-up. The analysis highlighted a clear clinical improvement for the study collective. The mean ODI improved from 41.6 preoperatively to 23.5 at the last follow-up (p<0.0036). EQ-5D VAS and EQ-5D index improved from 45.5 to 71.8 (p<0.0001) and from 0.454 to 0.693 (p<0.0002), respectively. Analysis of the sagittal balance revealed an increase of the total lumbar lordosis, however not in a statistically significant manner (p=0.164). Furthermore, an increase of 55.7% in mean disc height (from 7.0mm to 10.9mm) has been observed (p<0.0001). Surprisingly, the right foramen height was increased in a statistically significant manner compared to the left one, but both of them increased in absolute values. However, foraminal area on both sides did not significantly increase. The mean canal area was 115.7mm2 preoperatively and 136.5mm2 at follow-up (p=0.1325). Radiological fusion was observed in every case at the end of the follow-up period. The XLIF procedure accomplishes a secure and effective interbody fusion. This approach allows for an indirect decompression of neural structures by restoring foramen dimensions and disc space height, leading to an improvement of symptoms. Furthermore, XLIF seems to improve segmental sagittal balance.