MRI of unfused lumbar segments after spondylodesis.

Purpose: Our goal was to find a causal relation between disk degeneration in nonfused lumbar segments, back pain, and the angle of scoliotic curves 21-30 years after dorsal spondylodesis.

Method: Thirty-two patients with scoliosis had been treated by dorsal spondylodesis 21-30 years prior to this study (mean 25.2 +/- 2.4 years). With use of MRI, signs of disk degeneration in the nonfused lumbar segments (n = 131, mean 4.1 +/- 1.4) were evaluated. Back pain evaluation was performed using the Oswestry disability score. On plain X-ray films, the angle of scoliotic curves was measured (Cobb technique). Percentage and absolute number of degenerated disks were compared to the fusion level (number of unfused caudal segments), the Oswestry score, and the Cobb angle.

Results: Disk degeneration was present in 20 of 32 patients (62.5%) and in 37 of 131 unfused lumbar segments (28.2%). Of eight patients (24.2%), seven had moderate back pain and one severe back pain. The mean lumbar scoliotic curve was 44.4 +/- 24.9 degrees. No statistically significant correlation was found between patients with disk degeneration and fusion level, amount of back pain, or lumbar scoliotic angle (p < 0.05).

Conclusion: A lack of correlation between disk degeneration in unfused lumbar segments and other parameters like fusion level, back pain, and scoliotic angle can be assessed in the long-term follow-up of multisegment fusion of scoliotic curves.