The relationship between cage subsidence and lumbar sagittal alignment after oblique lumbar interbody fusion stand-alone

English Keywords:Oblique lumbar interbody fusion  Cage subsidence  Lumbar lordosis  Lumbar sagittal alignment

English Abstract:

  【Abstract】 Objectives: The purpose of this study was to assess the relationship between cage subsidence and lumbar sagittal alignment after oblique lumbar interbody fusion(OLIF) stand-alone. methods: In this study，the clinical data of 117 consecutive patients who underwent OLIF stand-alone were reviewed. Subsidence was classified using the following scale: grade 0, 0%-24% loss of postoperative disc height(DH); grade Ⅰ, 25%-49%; grade Ⅱ, 50%-74%; and grade Ⅲ, 75%-100%. All the patients were followed up for more than 2 years. DH improvement(postoperative DH-preoperative DH), segmental lordosis(SL) improvement(postoperative SL-preoperative SL), lumbar lordosis(LL) improvement(postoperative LL-preoperative LL) were evaluated, decrease of postoperative SL and LL were also recorded. Visual analogue scale(VAS) and Oswestry disability index(ODI) were compared. Logistic regression for cage subsidence after OLIF stand-alone was done. Results: All the operations were successfully done. 106 patients had grade 0 subsidence, 11 patients had grade Ⅰ subsidence, there was no grade Ⅱ, grade Ⅲ subsidence. 5 patients with grade Ⅰ subsidence underwent reoperation. The DH improvement and SL improvement in grade Ⅰ subsidence group was significantly larger than that in grade 0 subsidence group(P＜0.05). There was no significant difference in LL improvement in the two groups(P>0.05), DH improvement and SL improvement are independent risk factors for cage subsidence. The SL decrease and LL decrease in grade Ⅰ subsidence group was significantly larger than that in grade 0 subsidence group(P＜0.05). There was a significant decrease in VAS and ODI at all examinations postoperation(P＜0.05)， When comparing the two groups, The VAS scores and ODI scores in grade Ⅰ subsidence group was larger than that in grade 0 subsidence group at 1 month follow-up, but without statistical significance. The VAS scores and ODI scores in grade Ⅰ subsidence group was significantly larger than that in grade 0 subsidence group at the final follow-up(P＜0.05). Conclusions: In OLIF stand-alone, excessive reconstruction of DH and SL may lead to cage subsidence. Cage subsidence could result in SL and LL decrease, and affect clinical outcome.