Risk factors for adjacent segment disease after lumbar fusion

Abstract

The incidence of adjacent segment problems after lumbar fusion has been found to vary, and risk factors for these problems have not been precisely verified, especially based on structural changes determined by magnetic resonance imaging. The purpose of this retrospective clinical study was to describe the incidence and clinical features of adjacent segment disease (ASD) after lumbar fusion and to determine its risk factors. We assessed the incidence of ASD in patients who underwent lumbar or lumbosacral fusions for degenerative conditions between August 1995 and March 2006 with at least a 1-year followup. Patients less than 35 years of age at the index spinal fusion, patients with uninstrumented fusion, and patients who had not achieved successful union were excluded. Of the 1069 patients who underwent fusions, 28 (2.62%) needed secondary operations because of ASD and were included in this study. In order to identify the risk factors, we matched a disease group and a control group. The disease group consisted of 26 of the 28 patients with ASD, excluding the 2 patients for whom we did not have initial MRI data. Each patient in the disease group was matched by age, sex, fusion level and follow-up period with a control patient. The assumed risk factors included disc and facet degeneration, instability, listhesis, rotational deformity, and disc wedging. The mean age of the 28 patients with ASD requiring surgical treatment was 58.4 years, which did not differ significantly from that of the population in which ASD did not develop (58.2 years, p = 0.894). Of the 21 patients who underwent floating fusion, only 1 developed distal ASD. Facet degeneration was a significant risk factor (p \ 0.01) on logistic regression analysis. The incidence of distal ASD was much lower than that of proximal ASD. Pre-existing facet degeneration may be associated with a high risk of adjacent segment problems following lumbar fusion procedures.

Lumbar instrumented posterolateral fusion in spondylolisthetic and failed back patients: a long-term follow-up study spanning 11–13 years

“…However, the usefulness of the procedure remains uncertain. It is known that solid fusion can influence the biomechanics of the spine and thus may cause degeneration, leading within 10 years of the operation to adjacent segment alterations and symptoms in up to 40 % of patients [3][4][5][6][7][8]. Degenerative changes in discs, facet joints and ligaments can cause disc prolapses, stenosis and degenerative spondylolisthesis.…”

Adjacent segment degeneration after single-segment PLIF: the risk factor for degeneration and its impact on clinical outcomes

“…Battie et al [5] found that adjacent segment degeneration after fusion was a natural process that was not related to the fusion surgery. However, some other researchers conducted in vitro mechanical studies and found that lumbar fusion may induce abnormal intradiscal pressure and too much movement at the adjacent spinal levels, resulting in adjacent segment degeneration [6]. Therefore, it appears that ASD may be partially caused by the abnormal discal stresses distribution that arised by lumbar fusion and fixation [7][8][9].…”

Recurrent adjacent segment disease and cauda equina syndrome

“…The clinical relevance of ASD is low in the great majority of cases [2,[6][7][8]. Cauda equina syndrome is a very unusual onset of ASD.…”

“…ASD is likely a consequence of normal degenerative progression influenced by altered biomechanics related to fusion [1,2,4,6,[13][14][15][16]. Fusion length, stiffness of instrumentation, posterior interbody fusion, and sagittal balance could be important parameters linked to ASD [2][3][4]6].…”