Adjacent Segment Degeneration After Spinal Fusion In Lumbar Degenerative Disorders / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: A retrospective radiological assessment was conducted. OBJECTIVES: An attempt to analyze the degenerative change of an intervertebral disc for adjacent segment degeneration in lumbar degenerative diseases. LITERATURE REVIEW SUMMARY: A review of the literature failed to uncover any documented study examining the quantitative analysis of the degenerative change of the intervertebral disc for adjacent segment degeneration. METHODS: This study was based on 45 patients, treated operatively or conservatively at this hospital, between April 1995 and July 2004. 39 and 6 cases of operative and conservative treatments, respectively, were performed. In the 39 operative treatments, there were 34 cases of fusion and 5 of discectomy. Dynamic X-ray and MRI were performed at the initial evaluation, and again more than 2 years later. In the 34 fusion cases, the upper and lower adjacent segments of the fused level were studied, and in the 11 non-fusion cases (conservative treatment or discectomy), the L3-4, L4-5 and L5-S1 level were studied. The instability of the dynamic X-ray and Thompson grade changes of the disc on MRI were also evaluated. Statistical analysis was carried out using the Wilcoxon signed rank test. RESULTS: Adjacent segment degeneration was found in 10 of the 34 cases (29.4%) on plain X-ray. The average Thompson grades of the 33 upper segment cases were 2.6 and 3.4 preoperatively and postoperatively (P=0.000), and for the 24 of the lower segment cases were 2.9and 3.2 (P=0.033), respectively. No statistical increase in the Thompson grade was found in the non-fusion group. CONCLUSIONS: The adjacent discs of the fusion group showed statistically meaningful degeneration on MRI, but this was not correlated with adjacent segment degeneration on plain X-ray. Various anatomical and functional factors must be considered in the evaluation of adjacent segment disease.