Long-Term Changes in Sagittal Balance After Microsurgical Decompression of Lumbar Spinal Canal Stenosis in Elderly Patients: A Follow-Up Study for 5-Years After Surgery

-OBJECTIVE: The purpose of this study is to investigate long-term changes in spinal sagittal balance after micro-surgical decompression in lumbar canal stenosis (LCS).METHODS: Fifty-two patients who underwent microsur-gical decompression for symptomatic single level L4/5 spinal canal stenosis at our hospital were included in the study. All patients had standing full spine radiographs taken preoperatively, 1 year postoperatively, and 5 years postoperatively. Spinal parameters including sagittal bal-ance were measured from the obtained images. First, preoperative parameters were compared with 50 age-matched asymptomatic volunteers. Next, the parameters before and after surgery were compared to examine long-term changes.RESULTS: Sagittal vertical axis (SVA) was significantly increased in the LCS cases compared to the volunteers (P = 0.03). Postoperative lumbar lordosis (LL) was signif-icantly increased (P = 0.03). Postoperative mean SVA decreased but the difference was not significant (P = 0.12). Although there was no correlation between preop-erative parameters and the Japanese Orthopedic Associ-ation score, postoperative pelvic incidence (PI)-LL and pelvic tilt changes correlated with changes in Japanese Orthopedic Association score (PI-LL; P = 0.0001, pelvic tilt; P = 0.04). However, after 5 years of surgery, LL decreased and PI-LL increased (LL; P = 0.08, PI-LL; P = 0.03). Sagittal balance began to deteriorate but was not significant (P = 0.31). At 5 years postoperatively, 18 of 52 patients (34.6%) were found to have L3/4 adjacent segment disease. Cases with adjacent segment disease showed significantly worse SVA and PI-LL (SVA; P = 0.01, PI-LL; P < 0.01).CONCLUSIONS: In LCS, lumbar kyphosis improves and sagittal balance tends to improve after microsurgical decompression. However, after 5 years, adjacent interver-tebral degeneration occurs more frequently and sagittal balance begins to deteriorate in about one third of cases.

Automated summary

This study aimed to investigate the long-term changes in spinal sagittal balance after micro-surgical decompression in lumbar canal stenosis. It was found that postoperative lumbar lordosis increased and sagittal balance tended to improve. However, after 5 years, adjacent intervertebral degeneration occurred more frequently and sagittal balance began to deteriorate in about one third of cases.