Reoperation rate and risk factors of elective spinal surgery for degenerative spondylolisthesis: Minimum 5-year follow-up

Background context: The favorable outcome of surgical treatment for degenerative lumbar spondylolisthesis (DS) is widely recognized, but some patients require reoperation because of complications, such as pseudoarthrosis, persistent pain, infection, and progressive degenerative changes. Among these changes, adjacent segmental disease (ASD) and same segmental disease (SSD) are common reasons for reoperation. However, the relative risks of the various factors and their interactions are unclear. Purpose: The purpose of this study was to determine the longitudinal reoperation rate after surgery for DS and to assess the incidence and independent risk factors for ASD and SSD. Study design: This study is a retrospective consecutive case series of patients with DS who were surgically treated. Patient sample: We assessed 163 consecutive patients who were surgically treated for DS between 2003 and 2008. Individual patients were followed for at least 5 years after the initial surgery. Outcome measures: The primary end point was any type of second lumbar surgery. Radiographic measurements and demographic data were reviewed. We compared patients who underwent reoperation with those who did not. Logistic regression analysis was used to determine the relative risk of ASD and SSD in patients surgically treated for DS. Methods: Radiographic measurements and demographic data were reviewed. We identified the incidence and risk factors for reoperation, and we performed univariate and multivariate analyses to determine the independent risk factors for revision surgery for SSD and for ASD as the two distinct reasons for the reoperation. Age, gender, etiology, body mass index (BMI), and other radiographic data were analyzed to determine the risk factors for developing SSD and ASD. Results: The average patient age was 65.8 (50-81 years; 73 women and 90 men; mean follow-up, 5.9±1.6 years). Eighty-nine patients had posterior lumbar interbody fusion and 74 had laminotomies. Twenty-two patients had L3-L4 involvement and 141 had L4-L5 involvement. The cumulative reoperation rate was 6.1% at 1 year, 8.5% at 2 years, 15.2% at 3 years, 17.7% at 5 years, and 23.3% (38/163 patients) at the final follow-up. A significantly higher reoperation rate was observed for patients undergoing laminotomy than for patients undergoing posterior lumbar interbody fusion (33.8% vs. 14.4%, p=.01). Eighteen patients (11.0%) had SSD, and 13 patients (8.9%) developed ASD. Higher BMI (obesity) and greater disc height (greater than 10 mm) predicted the occurrence of SSD in the multivariate model (BMI=odds ratio 4.11 [95% confidence interval 1.29-13.11], p=.016; disc height=3.18 [1.03-9.82], p=.044), and gender (male) and facet degeneration (Fujiwara grade greater than 3) predicted the development of ASD in the multivariate model (gender=4.74 [1.09-20.45], p=.037; facet degeneration=6.31 [1.09-36.52], p=.039). Conclusions: The incidence of reoperation in patients surgically treated for DS was 23.2% at a mean time of 5.9 years. A significantly higher incidence of reoperation was observed in patients treated with decompression alone compared with those treated with decompression and fusion. Body mass index and disc height were identified as independent risk factors for SSD, whereas male gender and facet degeneration were identified as independent risk factors for ASD. The results of this comprehensive review will guide spine surgeons in their preoperative planning and in the surgical management of patients with DS, thereby reducing the reoperation rate.