P124. Does simultaneous decompression above a fusion lead to progressive adjacent segment disease requiring revision surgery?

Abstract

<h3>BACKGROUND CONTEXT</h3> Degenerative spondylolisthesis (DS) is a condition that often requires surgical treatment. This treatment varies based on surgeon preference and the extent of lumbar pathology seen on imaging. There is controversy regarding the surgical management of segments adjacent to the level of DS that require decompression. While it is understood that decompression and fusion of affected levels is necessary, it is unclear how best to treat levels adjacent to the level of DS. Some surgeons will always fuse any additional levels that require decompression while others will decompress adjacent segments without extending the fusion. Each technique has its own theoretical risks, but analysis of adjacent segment disease (ASD) and need for repeat surgery has not been extensively studied. <h3>PURPOSE</h3> The primary aim is to identify the rate of and risk factors related to progression of ASD and the need for revision surgery in patients with surgically treated DS. The secondary aim is to analyze the efficacy of decompressing adjacent levels without fusion. <h3>STUDY DESIGN/SETTING</h3> All patients treated surgically for DS at a tertiary care medical center over a 5-year period were retrospectively reviewed. Patients were divided into two cohorts consisting of those patients who were fused at all decompressed levels versus those who were not fused at all decompressed levels. <h3>PATIENT SAMPLE</h3> Adult patients who had decompression and fusion of affected levels with decompression of adjacent levels and at least 1 year of followup were included. There were 137 such patients identified. <h3>OUTCOME MEASURES</h3> Patient demographics, level(s) of DS at presentation, ASD rates and reoperation rates were measured and analyzed. Rates of ASD were measured based on clinical presentation, radiographic results and/or need for reoperation. <h3>METHODS</h3> Descriptive statistics were used to summarize demographic and comorbidity data. Relative risks were calculated and two proportion z-test was used to compare rates of adverse events in the two surgical cohorts. Odds ratios were calculated for risk factors associated with adverse events. <h3>RESULTS</h3> Of the 137 patients, 86 (63%) were female and 51 (37%) were male. The average followup was 19.9 months. There were 119 (87%) patients with single level DS and 18 (13%) with DS at two adjacent levels. The most common level for DS was L4-5 (100, 73%). Thirty-four patients underwent a multilevel decompression and fusion only at the level of the DS, while 103 had a fusion at all the decompressed levels. Twelve patients (9%) had progression of ASD requiring extension of their construct; 11 of these patients were female (92%), however female sex was not a statistically significant risk factor for ASD (p = 0.06). Of the 12 patients, 3 had DS at L3-4, 9 at L4-5 and 2 at L5-S1. Two patients were decompressed more levels than fused, and 10 were fused at all levels decompressed. Neither level of DS nor surgical technique correlated with increased risk of ASD. <h3>CONCLUSIONS</h3> Progression of ASD requiring revision surgery is a risk after surgery for DS. The data demonstrates that there is no additional risk of ASD if adjacent levels are decompressed without fusion. This is the first study to our knowledge that shows equal efficacy of decompression without fusion of adjacent levels for the treatment of lumbar DS. The researchers will next compare radiographic and patient-reported outcome data between patients treated with decompression of adjacent segments only versus those treated with decompression and fusion of adjacent segments. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.