P88. Revision surgery for pseudarthrosis after surgical correction with pedicle subtraction osteotomy in adult spinal deformity: comparison of rod change only, anterior lumbar interbody fusion around pedicle subtraction osteotomy, and 4-rod constructs

Abstract

BACKGROUND CONTEXT Pseudarthrosis is the most common cause of revision surgery after sagittal correction with long posterior spinal fusion (PSF) in patients with ASD. Although revision surgery for pseudarthrosis after surgical correction of adult spinal deformity (ASD) remains challenging and without consensus, previous studies did not sufficiently compare the methods of revision surgery. PURPOSE We aimed to determine the most useful of the following three methods of revision surgery: surgery for rod change only, anterior lumbar interbody fusion (ALIF) around pedicle subtraction osteotomy (PSO), and 4-rod constructs. STUDY DESIGN/SETTING Retrospective, consecutive case review. PATIENT SAMPLE A total of 79 patients (average age 70.5 years) who were diagnosed adult spinal deformity with sagittal imbalance and followed up for more than 5 years after surgical correction with pedicle subtraction osteotomy. OUTCOME MEASURES Description and analysis of X-ray changes. METHODS There were 42 revision surgeries for pseudarthrosis performed by one of three methods: rod change with 2-rod constructs (n=16), anterior lumbar interbody fusion around PSO with rod change (n=9), and rod change with 4-rod constructs (n=17). RESULTS Preoperative lumbar lordosis was corrected (69.4˚) from 3.6° to -65.8˚ while sagittal vertical axis (SVA) was corrected (185.7 mm) from 176.9 mm to -8.8 mm. Pseudarthrosis occurred (42/79, 53%) around PSO site on the average of 21 months after the surgery, so that revision surgery was performed. There were no statistically significant differences among the other risk factors except the surgical methods for the three groups. Re-pseudarthrosis occurred in 4 of 42 (9.5%) cases in patients who received rod change using the 2-rod constructs method around PSO site at 15, 18, 24 and 35 months postoperatively, and there was no re-pseudarthrosis in the other two groups (P=0.042). CONCLUSIONS Our study showed that anterior lumbar interbody fusion around PSO and 4-rod constructs are preferable to rod change with 2-rod constructs. Therefore, our research can provide an effective guideline for revision surgery for pseudarthrosis that occurs after long PSF with PSO. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.