【INTRODUCTION】Although the indications for posterior lumbar interbody fusion (PLIF) have been expanded for the elderly, there are few reports comparing the surgical outcomes of patients aged 80 years or older with those of other ages. The purpose of this study is to compare the surgical outcomes of PLIF in the 80s and 60s patients using Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), which is a patient self-administered questionnaire.

【METHODS】This study is a retrospective study conducted at two institutions in Japan. We reviewed a total of 1061 consecutive patients who underwent PLIF for lumbar degenerative surgery. Patients with failed back syndrome or lumbar spinal stenosis with osteoporotic vertebral fracture were excluded. In order to focus on the clinical characteristics of the 80s patients, we compared them with the 60s patients, who are apart in age with the 80s patients. We investigated patient demographics, American society of anesthesiologists physical status (ASA-PS), and Charlson comorbidity index (CCI) preoperatively. In addition, visual analog scale (VAS) for low back pain, leg pain, and leg numbness and JOABPEQ were analyzed preoperatively and at 1-year follow-up. Statistical analyzes were performed using Mann-Whitney U-test, Pearson’s chi-square test, and Wilcoxon signed-rank test. 

【RESULTS】Of 1061 patients, 52 were in the Group 80s (mean age: 82.0 ± 2.2 years) and 322 were in the Group 60s (mean age: 64.8 ± 2.7 years). There was no statistical difference between the 2 groups in sex (%male: 44.2% vs. 40.2%, P = 0.648). Preoperative ASA-PS (8 Grade 1 patients (15%), 33 Grade 2 (64%), 11 Grade 3 (21%) vs. 135 Grade 1 (42%), 168 Grade 2 (52%), 20 Grade 3 (6%), P < 0.001) and CCI (0.92 ± 1.19 vs. 0.46 ± 1.19, P = 0.007) in the Group 80s were higher than those in the Group 60s. Preoperative VAS scores for low back pain were significantly higher in the Group 80s than in the Group 60s (5.8 ± 2.9 vs. 4.9 ± 2.8, P = 0.024). Although all postoperative VAS scores at 1-year follow-up were significantly improved compared with preoperative scores in both of the 2 groups (P < 0.001), postoperative VAS scores for leg numbness were higher in the Group 80s than in the Group 60s (3.4 ± 3.2 vs. 2.0 ± 2.6, P = 0.004). The effective rates of the pain disorder (62.5% vs. 82.0%, P = 0.002), walking ability (70.6% vs. 83.9%, P = 0.022), and social life domain (47.1% vs. 63.7%, P = 0.023) in the JOABPEQ were lower in the Group 80s than in the Group 60s.  

【DISCUSSION】Elderly patients aged 80 years or older had more comorbidities, severer postoperative residual low back pain and leg numbness, and poorer improvements in walking ability and social life disorders compared with the 60s patients. However, the therapeutic effect of PLIF was obtained even in the 80s patients, there were no differences in surgical outcomes of lumbar function and psychological disorders. Further investigation of risk factors that reduce surgical therapeutic effect in the 80s patients is crucial in the future.