Adjacent segment stenosis after lumbar fusion requiring second operation

Background Whereas degeneration of the segment adjacent to lumbar fusion has been often seen on radiographs, a small number of patients with such degenerative changes undergo reoperation. Most follow-up studies have focused on adjacent segment disease based on analysis of radiographs. The present study was conducted to understand the pathology of reoperation cases of adjacent segment disease and factors associated with this condition. Operative indication was consistently restricted to patients with neurological involvement. Methods. The subjects were 117 patients who had undergone posterior lumbar fusion and were followed for a minimum of 2 years (mean 7 years). Among them, nine patients (7.7%) required a second operation owing to symptomatic adjacent segment disease (stenosis). The reoperation rate was assessed in relation to sex, age, initial pathologic condition, and initial spinal fusion and decompression methods. Data were analyzed in a 2 x 2 cross contingency table using Fisher's exact probability test. A probability of < 0.05 was defined as statistically significant. Results. Of the variables examined, only multilevel fusion was associated with a high rate of reoperation with statistical significance (P < 0.04). Two patients (100%) suffering from loss of coronal balance (degenerative scoliosis) also required a second operation. Conclusions. The reoperation rate of 7.7% for adjacent segment disease in this study was consistent with the prevalence of adjacent segment stenosis in the literature. Given the risk of later occurrence of adjacent segment stenosis following multisegment posterolateral fusion, correction of coronal and sagittal balance, preventive decompression of the adjacent segment, or selective decompression without fusion may have to be considered as an additional or alternative procedure.