Abstract:Objective To explore changes of sagittal parameters and clinical outcome after L4~5 single segment fusion,and to analyze the influencing factors of clinical efficacy.Methods 46 patients (29 men and 17 women) who had complete followup date and received transforaminal lumbar interbody fusion (TLIF) of L4~5single segment in our hospital between January 2010 and January 2011 were enrolled in the study.The average age were (52.3±11.0) and the mean follow-up was (39.2±11.1)months(25~58 months) .The pain status of the lower limbs and the lower back pain were assessed by visual analogue scale (VAS),the functional status was assessed by the Oswestry Dysfunction Index (ODI),and sagittal parameters were measured using standing fulllength lateral radiographs before surgery,at the third month after surgery and final follow up respectively.The relationship between clinical efficacy and sagittal parameters was analyzed.Results The VAS scores of lower limbs and low back pain and the ODI scores were all lower at the third month after operation and the last follow-up than those before operation and the differences were statistically significant (P<0.05).There were no statistically significant differences for thoracic kyphosis (TK) and pelvic incident (PI) at 3 months and the last follow-up compared with those before surgery.The lumbar lordosis (LL),sacral slope (SS),PI-LL,L4~5 intervertebral height and intervertebral angle were significantly higher at the third month after surgery than those before operation and the differences were statistically significant (P<0.05).At the last follow-up,LL,L4~5 intervertebral height and intervertebral angle were significantly higher than those before operation,PT and PI-LL were less than preoperative,and the differences were statistically significant (P<0.05).Logistic regression analysis showed that LL,SS,L4~5 intervertebral height and intervertebral angle were the factors that affected the clinical efficacy.Clinical results were better in patients with greater LL,SS,L4~5 intervertebral height and intervertebral angle.Conclusion TLIF of L4~5 single segment can achieve good clinical results and improve the sagittal alignment.LL,SS,L4~5 intervertebral height and intervertebral angle are important factors affecting clinical efficacy and should be fully considered in the development of surgical strategy.