Ekman Per, Möller Hans, Shalabi Adel, Yu Yiang Xiao, Hedlund Rune
Division of Orthopedics, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska University Hospital Huddinge, Karolinska Institutet, 141 86, Stockholm, Sweden.
Eur Spine J. 2009 Aug;18(8):1175-86. doi: 10.1007/s00586-009-0947-3. Epub 2009 Apr 1.
The existence and importance of an accelerated adjacent segment disc degeneration (ASD) after lumbar fusion have previously not been demonstrated by RCTs. The objectives of this study were, to determine whether lumbar fusion in the long term accelerates degenerative changes in the adjacent disc and whether this affects the outcome, by using a prospective randomised design. A total of 111 patients, aged 18-55, with isthmic spondylolisthesis were randomised to exercise (EX, n = 34) or posterolateral fusion (PLF, n = 77), with (n = 37) or without pedicle screw instrumentation (n = 40). The minimum 10 years FU rate was 72%, with a mean FU time of 12.6 years (range 10-17 years). Three radiographic methods of ASD quantification were used, i.e. two digital radiographic measurement methods and the semi quantitative UCLA grading scale. One digital measurement method showed a mean disc height reduction by 2% in the EX group and by 15% in the PLF group (p = 0.0016), and the other showed 0.5 mm more disc height reduction in the PLF compared to the Ex group (ns). The UCLA grading scale showed normal discs in 100% of patients in the EX group, compared to 62% in the PLF group (p = 0.026). There were no significant differences between instrumented and non-instrumented patients. In patients with laminectomy we found a significantly higher incidence of ASD compared to non laminectomised patients (22/47 vs. 2/16 respectively, p = 0.015). In the longitudinal analysis, the posterior and anterior disc heights were significantly reduced in the PLF group, whereas in the EX group only the posterior disc height was significantly reduced. Except for global outcome, which was significantly better for patients without ASD, the clinical outcome was not statistically different in patients with and without ASD. In conclusion, the long-term RCT shows that fusion accelerates degenerative changes at the adjacent level compared with natural history. The study suggests that not only fusion, but also laminectomy may be of pathogenetic importance. The clinical importance of ASD seems limited, with only the more severe forms affecting the outcome.
腰椎融合术后加速相邻节段椎间盘退变（ASD）的存在及其重要性此前尚未通过随机对照试验（RCT）得到证实。本研究的目的是，采用前瞻性随机设计，确定长期腰椎融合是否会加速相邻椎间盘的退变改变，以及这是否会影响治疗结果。共有111例年龄在18至55岁之间的峡部裂型腰椎滑脱患者被随机分为运动组（EX，n = 34）或后外侧融合组（PLF，n = 77），其中37例使用椎弓根螺钉内固定（n = 37），40例未使用（n = 40）。最小随访10年的随访率为72%，平均随访时间为12.6年（范围10 - 17年）。采用了三种ASD量化的影像学方法，即两种数字X线测量方法和半定量的UCLA分级量表。一种数字测量方法显示，EX组椎间盘高度平均降低2%，PLF组降低15%（p = 0.0016），另一种方法显示PLF组比EX组椎间盘高度多降低0.5mm（无统计学意义）。UCLA分级量表显示，EX组100%的患者椎间盘正常，而PLF组为62%（p = 0.026）。使用内固定和未使用内固定的患者之间无显著差异。在接受椎板切除术的患者中，我们发现与未接受椎板切除术的患者相比，ASD的发生率显著更高（分别为22/47和2/16，p = 0.015）。在纵向分析中，PLF组的椎间盘前后高度均显著降低，而EX组仅后椎间盘高度显著降低。除了无ASD患者的整体治疗结果明显更好外，有ASD和无ASD患者的临床结果在统计学上没有差异。总之，长期RCT表明，与自然病程相比，融合会加速相邻节段的退变改变。该研究表明，不仅融合，椎板切除术可能在发病机制上也具有重要意义。ASD的临床重要性似乎有限，只有较严重的形式会影响治疗结果。
