Abstract
BackgroundAdjacent segment disease (ASD) is an acknowledged problem of posterior lumbar interbody fusion (PLIF). Many studies have been reported concerning the role of lordosis distribution index (LDI) in spinal biomechanics. However, few reports have been published about the impact of LDI on ASD following L4-S1 PLIF.MethodsThe study enrolled 200 subjects who underwent L4-S1 PLIF for degenerative spine disease from 2009 to 2014. The average follow-up term was 84 months. Several lower lumbar parameters were measured, including lower lumbar lordosis (LLL), lumbar lordosis (LL), pelvic incidence (PI), and LDI on the pre and postoperative radiograph. Perioperative information, comorbidities, and operative data were documented. Kaplan-Meier curves were plotted for the comparisons of ASD-free survival of 3 different types of postoperative LDI subgroups.ResultsThe incidence of ASD was found to be 8.5%. LL and LLL increased by 3.96° (38.71° vs 42.67°; P < 0.001) and 3.60° (26.22° vs 28.82°; P < 0.001) after lower lumbar fusion surgery, respectively. Lordosis distribution index (LDI) increased by 0.03 (0.66 vs 0.69, P = 0.004) postoperatively. A significant difference (P = 0.001) was observed when comparing the incidence of ASD among postoperative LDI subgroups. The Kaplan-Meier curves showed a marked difference in ASD-free survival between low and moderate LDI subgroup (log-rank test, P = 0.0012) and high and moderate LDI subgroup (log-rank test, P = 0.0005).ConclusionPatients with abnormal postoperative LDI were statistically more likely to develop ASD than those who had normal postoperative LDI. Moreover, patients with low postoperative LDI were at greater risk for developing ASD than those with high postoperative LDI over time.
Highlights
Posterior lumbar interbody fusion (PLIF) with pedicle screw fixation has been widely applied to treat various lumbar spinal disorders including lumbar spinal stenosis, lumbar disc herniation, degenerative spinal deformity, instability, spondylolisthesis, and vertebral compression fracture
There have been plenty of studies suggesting the risk factors for the development of Adjacent segment disease (ASD) after lumbar spinal fusion, including age, gender, obesity, body mass index (BMI), fusion length, osteoporosis, laminectomy performed adjacent to a segment, preoperative segmental instability at the adjacent level, preexisting degenerated disc prior to fusion, and excessive disc height distraction [9,10,11,12]
The segment lesions were identified at the level above the fusion and all of them were assigned to the ASD group
Summary
Posterior lumbar interbody fusion (PLIF) with pedicle screw fixation has been widely applied to treat various lumbar spinal disorders including lumbar spinal stenosis, lumbar disc herniation, degenerative spinal deformity, instability, spondylolisthesis, and vertebral compression fracture. Despite the capability of PLIF with pedicle screw fixation to provide solid instrumentation and to achieve satisfactory clinical effects, it has a potential to alter the normal biomechanics of the spine and to accelerate the degenerative process of adjacent unfused segments, increasing the risk of developing adjacent segment disease (ASD) [1,2,3,4,5,6]. There remain few studies demonstrating the impact of LDI on ASD following lower lumbar spine surgery. Few reports have been published about the impact of LDI on ASD following L4-S1 PLIF
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