Introduction: With increasing life expectancy and health expectancy, number of elderly patients requiring lumbar interbody fusion has continuously increased. However, when the patient was extremely elderly, surgeon tend to choose lumbar decompression surgery instead of lumbar fusion with instrumentation. One of the reasons is that postoperative outcomes of lumbar spine fusion for the extremely elderly remains unknown. The aim of this study was to evaluate the outcomes of lumbar interbody fusion in the elderly over 85 years of age.

Methods: Twenty-nine patients (8 males and 21 females) aged 85 years or older who underwent single or double PLIF/TLIF for lumbar degenerative disease at our hospital from 2012 to 2019 were retrospectively studied (minimum follow-up period of 2 years, follow-up rate: 81%). For each extremely elderly patient, 3 control patients whose age were from 60 years to 75 years were randomly selected using a random number table. Each control patient underwent a procedure of similar complexity, with the same gender and the same fusion levels in the same part of the spine, performed during the preceding or following year. Oswestry Disability Index (ODI), the visual analogue scale (VAS) scores for low back pain (LBP) and leg pain, and the recovery rate of Japanese Orthopaedic Association (JOA) score were assessed during the postoperative follow-up. The lumbar interbody fusion rate was evaluated by CT scanning, and perioperative complication was reviewed from the medical records.

Results: Preoperative JOA score was significantly lower in Extremely elderly group than in Control group (10.9 vs. 13.5, P = 0.02), whereas preoperative ODI was not significantly different between the two groups (29.1 vs. 28.0, P = 0.74). The means of the 2-year postoperative clinical score for the recovery rate of the JOA score (58.1% vs. 62.1%, P = 0.62), ODI (10.8 vs.9.3, P = 0.54), and VAS of leg pain (14.5/100 mm vs. 11.1/100 mm, P = 0.47) were not significantly different between Extremely elderly group and Control group (Figure 1). On the other hand, VAS of LBP was significantly lower in Extremely elderly group than in Control group (5.9/100 mm vs. 18.0/100 mm, P = 0.01). The fusion rate was 90% in Extremely elderly group and 94% in Control group (P = 0.44). In Extremely elderly group, there were 3 cases of delirium, one case of surgical site infection, and in Control group, there were one case of delirium, 2 cases of surgical site infection, and 4 cases of dural injury. Perioperative complication rate was not significantly different between the two groups (13.7% vs. 8.0%, P = 0.36).

Discussion: Lumbar interbody fusion in the elderly over 85 years of age is effective procedure with no difference compared with the Control group. When the pathology requires spinal fusion, lumbar fusion with instrumentation is worth to be chosen even in the elderly over 85 years of age.