Department of Neurosurgery, Royal North Shore Hospital, Sydney, NSW 2065, Australia.
Spine J. 2011 Jan;11(1):11-20. doi: 10.1016/j.spinee.2010.09.026.
Adjacent segment disease (ASD) after lumbar spinal fusion has been an important reason behind the development of nonfusion stabilization technology. However, the incidence, prevalence, and factors contributing to adjacent segment degeneration in the lumbar spine remain unclear. A range of prevalence rates for ASD have been reported in the lumbar spinal literature, but the annual incidence has not been widely studied in this region. Conflicting reports exist regarding risk factors, especially fusion length.
To determine the annual incidence and prevalence of further surgery for adjacent segment disease (SxASD) after posterior lumbar arthrodesis and examine possible risk factors.
Retrospective cohort study.
Nine hundred twelve patients who underwent 1,000 consecutive posterior lumbar interbody fusion procedures, with mean follow-up duration of 63 months (range, 5 months-16 years).
Further surgery for ASD or surgery-free survival.
A postal and telephone survey. Follow-up rate: 91% of patients. The annual incidence and prevalence of ASD requiring further surgery were determined using Kaplan-Meier survivorship analysis. Cox proportional-hazards (Cox) regression was used for multivariate analysis of possible risk factors. Significance was set at p<.05.
Further surgery for ASD occurred following 130 of 1,000 or 13% of procedures at a mean time of 43 months (range, 2.3-162 months). The mean annual incidence of SxASD over the first 10 years, in all patients, was 2.5% (95% confidence interval [95% CI], 1.9-3.1) with prevalences of 13.6% and 22.2% at 5 and 10 years, respectively. Cox regression modeling found that the number of levels fused (p≤.0003), age of the patient, fusing to L5, and performing an additional laminectomy adjacent to a fusion all independently affect the risk of SxASD. The mean annual incidence figures in the first 10 years after a lumbar fusion were 1.7% (95% CI, 1.3-2.2) after fusion at single levels, 3.6% (2.1-5.2) after two levels, and 5.0% (3.3-6.7) after three and four levels. The 5- and 10-year prevalences were 9% and 16%, 17% and 31%, and 29% and 40% after single-, two-, and three-/four-level fusions, respectively. The risk of SxASD in patients younger than 45 years was one-quarter (95% CI, 10-64) the risk of patients older than 60 years (p=.003). A laminectomy adjacent to a fusion increases the relative risk by 2.4 times (95% CI, 1.1-5.2; p=.03). Stopping a fusion at L5 is associated with a 1.7-fold increased risk (95% CI, 1.2-2.4; p=.007) of SxASD compared with a fusion to S1, for fusions of the same length.
The overall annual incidence and predicted 10-year prevalence of further surgery for ASD after lumbar arthrodesis were 2.5% and 22.2%, respectively. These rates varied widely depending on the identified risk factors. Although young patients who underwent single-level fusions were at low risk, patients who underwent fusion of three or four levels had a threefold increased risk of further surgery, compared with single-level fusions (p<.0001), and a predicted 10-year prevalence of 40%.
腰椎融合术后的邻近节段疾病（ASD）一直是非融合稳定技术发展的重要原因。然而，腰椎脊柱融合后邻近节段退变的发病率、患病率和相关因素仍不清楚。在腰椎脊柱文献中已经报道了一系列 ASD 的患病率，但在该区域尚未广泛研究其年发病率。关于危险因素，特别是融合长度，存在相互矛盾的报告。
确定腰椎后路融合术后邻近节段疾病（SxASD）进一步手术的年发病率和患病率，并探讨可能的危险因素。
回顾性队列研究。
912 例患者接受了 1000 例连续后路腰椎椎间融合术，平均随访时间为 63 个月（范围，5 个月至 16 年）。
SxASD 的进一步手术或手术无生存。
通过邮寄和电话调查。随访率：91%的患者。使用 Kaplan-Meier 生存分析确定需要进一步手术的 ASD 的年发病率和患病率。使用 Cox 比例风险（Cox）回归分析可能的危险因素的多变量分析。显著性水平设置为 p<.05。
在 1000 例手术中，有 130 例（13%）或 130 例手术需要进一步手术治疗 ASD，平均时间为 43 个月（范围，2.3-162 个月）。所有患者在第 10 年之前的 SxASD 年发病率平均为 2.5%（95%置信区间[95%CI]，1.9-3.1），5 年和 10 年的患病率分别为 13.6%和 22.2%。Cox 回归模型发现，融合节段数（p≤.0003）、患者年龄、融合至 L5 以及在融合相邻进行额外的椎板切除术均独立影响 SxASD 的风险。腰椎融合术后第 10 年的平均年发病率为单节段融合后 1.7%（95%CI，1.3-2.2），双节段融合后 3.6%（2.1-5.2），三节段和四节段融合后 5.0%（3.3-6.7）。5 年和 10 年的患病率分别为单节段融合后 9%和 16%，双节段融合后 17%和 31%，三节段和四节段融合后 29%和 40%。年龄小于 45 岁的患者发生 SxASD 的风险是年龄大于 60 岁患者的四分之一（95%CI，10-64）（p=.003）。在融合相邻处进行椎板切除术，相对风险增加 2.4 倍（95%CI，1.1-5.2；p=.03）。与融合至 S1 相比，融合至 L5 会使同一长度融合的 SxASD 风险增加 1.7 倍（95%CI，1.2-2.4；p=.007）。
腰椎后路融合术后 ASD 进一步手术的总年发病率和预测 10 年患病率分别为 2.5%和 22.2%。这些比率因确定的危险因素而有很大差异。虽然接受单节段融合的年轻患者风险较低，但与单节段融合相比，接受三或四节段融合的患者进一步手术的风险增加了三倍（p<.0001），预测 10 年患病率为 40%。
