Predictable Risk Factors for Adjacent Segment Degeneration After Lumbar Fusion

Hyun, Seung Jae; Kim, Young Baeg; Hong, Hyun Jong; Kwon, Jeong Taik; Suk, Jong Sik; Min, Byung Kook

Abstract

OBJECTIVE
The aim of this study is to investigate predictable risk factors for radiologic degeneration of adjacent segment after lumbar fusion and preoperative radiologic features of patients who underwent additional surgery with adjacent segment degeneration.
METHODS
Between January 1995 and December 2002, 201 patients who underwent lumbar fusion for degenerative conditions of lumbar spine were evaluated. We studied radiologic features, the method of operation, the length of fusion, age, sex, osteoporosis, and body mass index. Special attention was focused on, preoperative radiologic features of patients who required additional surgery were studied to detect risk factors for clinical deterioration.
RESULTS
Follow-up period ranged from 3 to 11 years. In our study, 61 (30%) patients developed adjacent segment degeneration, and 15 (7%) patients required additional surgery for neurologic deterioration. Age, the postoperative delay, facet volume, motion range, laminar inclination, facet tropism, and preexisting disc degeneration of adjacent segment considered as possible risk factors. Among these, laminar inclination and preexisting disc degeneration of adjacent segment were significantly correlated with clinical deterioration.
CONCLUSION
The radiologic degeneration of adjacent segment after lumbar fusion can be predicted in terms of each preoperative radiologic factor, age and the postoperative delay. Laminar inclination and preexisting disc degeneration of adjacent segment have shown as strong risk factors for neurologic deterioration. Thus, careful consideration is warranted when these risk factors are present.