MRI OF UNFUSED LUMBAR SEGMENTS AFTER SPONDYLODESIS

Purpose: Our goal was to find a causal relation between disk degenerat ion in nonfused lumbar segments, back pain, and the angle of scoliotic curves 21-30 years after dorsal spondylodesis. Method: Thirty-two pat ients with scoliosis had been treated by dorsal spondylodesis 21-30 ye ars prior to this study (mean 25.2 +/- 2.4 years). With use of MRI, si gns of disk degeneration in the nonfused lumbar segments (n = 131, mea n 4.1 +/- 1.4) were evaluated. Back pain evaluation was performed usin g the Oswestry disability score. On plain X-ray films, the angle of sc oliotic 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. R esults: 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 lu mbar scoliotic curve was 44.4 +/- 24.9 degrees. No statistically signi ficant correlation was found be tween 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 p ain, and scoliotic angle can be assessed in the long-term follow-up of multisegment fusion of scoliotic curves.