[EFFECT OF BODY MASS INDEX ON OUTCOME OF POSTERIOR 360 DEGREES FUSION FOR SINGLE-LEVEL LUMBAR DEGENERATIVE DISEASES].

OBJECTIVE:To investigate the effect of body mass index (BMI) on the outcome of posterior 360 degrees fusion for single-level lumbar degenerative diseases. METHODS:A retrospective study was carried on 302 cases of single- level lumbar degenerative diseases treated with posterior 360 degrees fusion between September 2009 and September 2013. All patients were divided into 3 groups according to BMI: normal weight (BMI<24 kg/M2) in 105 cases (group A), overweight (24 kg/M2 < or = BMI < 28 kg/M2) in 108 cases (group B), and obese (BMI > or = 28 kg/m2) in 89 cases (group C). There was no significant difference in gender, age, disease duration, disease patterns, affected segments, preoperative Japanese Orthopaedic Association (JOA) score and Oswestry disability index (ODI) among 3 groups (P>0.05). The operation time, intraoperative blood loss, postoperative hospital stay, and complications were recorded. The lumbar function was assessed by JOA score and ODI at pre- and post-operation (at 3, 6, and 24 months). RESULTS:The operation time, intraoperative blood loss, and postoperative hospital stay of group C were significantly more than those of groups A and B (P<0.05), but no significant difference was found between group A and group B (P>0.05). The patients were followed up 24-45 months. Postoperative JOA score and ODI showed significant improvements in each group when compared with preoperative ones (P<0.05), but there was no significant difference among groups at each time point after operation (P>0.05). There was no significant difference in the incidence of total complications among 3 groups (chi2 = 3.288, P=0.193). The incidence of incision-related complications (infection and poor healing) in group C was significantly higher than that of groups A and B (P<0.05), but no significant difference was shown between group A and group B (P>0.05). However, there was no significant difference in cerebrospinal fluid leak, pseudarthrosis formation, and revision among 3 groups (P>0.05). CONCLUSION:Posterior 360 degrees fusion for single-level lumbar degenerative diseases can obtain good effectiveness in patients with different BMI, but patients whose BMI was > or = 28 kg/in2 have longer operation time, more intraoperative blood loss, longer hospital stay, and higher incidence of postoperative incision-related complications.