Late complications of adult idiopathic scoliosis primary fusions to L4 and above: the effect of age and distal fusion level.

Abstract

STUDY DESIGN A retrospective analysis of primary cases of adult idiopathic scoliosis treated with long instrumented fusions from the thoracic spine proximally to segments that range from T11 to L4 distally. To analyze whether patients requiring revision surgery had lower postoperative SRS-24 scores; age >or=40 years correlated with higher rates of revision surgery; disc degeneration below the fusion occurred more commonly with a more distal lowest instrumented vertebra or older patient age (>or=40 years); and whether smokers had higher rates of major complications or revision surgery. Few reports describe complications related to primary long fusions using modern 2+ rods, hook/pedicle screw instrumentation methods in the treatment of adult idiopathic scoliosis. Sixty-seven patients were analyzed with an average age of 38.8 years (range 21-61 years). The average clinical follow-up was 7.8 years (range 2-16 years): 42 patients had >5 years follow-up, including 23 patients with >10 years follow-up. Patients were categorized by age (< or >or=40 years) and level of the lowest instrumented vertebra (T11-L2 vs. L3-L4). Upright radiographs and postoperative SRS-24 questionnaires from the latest follow-up date were analyzed. Patients requiring revision surgery had lower total score (average 72.0) than those that did not (total score = 94.2; P = 0.01). More specifically, patients with pseudarthrosis had lower total scores (average 74.7) than those without (average total score = 93.5; P = 0.02). When analyzing age, there were similar rates of pseudarthrosis, but higher rates of transition syndrome (2) and sagittal/coronal imbalance (1 each) in patients >or=40 years. Subsequent distal disc degeneration did not correlate significantly with more distal lowest instrumented vertebra or older patient age. Smokers did not have higher rates of major complications or revision surgery than nonsmokers. Patients with adult idiopathic scoliosis and long fusions had similar pseudarthrosis rates, but higher rates of transition syndrome when lowest instrumented vertebra was L3-L4 relative to levels T11-L2. When categorized by age, complication rates were similar in each group. Patients with pseudarthroses or other diagnoses requiring revision surgery had lower SRS-24 total scores than those without (P = 0.02 and P = 0.01, respectively).