Long-term influence of associated arthrodesis on adjacent segments in the treatment of lumbar stenosis: a series of 127 cases with 9-year follow-up

Purpose of the study Little is known about the impact of posterolateral arthrodesis on adjacent levels. In order to examine this question, we analyzed the radiological evo lution of the lumbar spine in patients treated for lumbar stenosis, compari ng cases where posterolateral arthrodesis was used with the other cases. Ou r aim was to determine whether the long-term radiographical modifications w ere affected by the arthrodesis. Material and methods Among our series of patients presenting with lumbar stenosis between 1984 a nd 1992, we retained two groups: patients in group 1 (n = 46) who underwent single-level decompressions at L4-L5 or L4-L5 and L5-S1 level; and patient s in group II (n = 81) who underwent decompressions on the same levels asso ciated with posterolateral arthrodesis extending from L4 to the sacrum with or without instrumentation. We compared the course of the two levels above the decompression (L2-L3 and L3-L4) between the two groups. We compared th ree radiological parameters: disc height, intervertabral slipping, and inte rsegmental mobility. We also examined the correlations between radiological modifications and functional outcome. Mean follow-up for these 127 patient s was 9 years. Results The two groups were comparable for age, gender, follow-up, and presurgical functional score, disc height and intervertebral slipping at equivalent lev els. At last follow-up, disc narrowing was observed at L2-L3 and L3-L4; it was significantly greater in the group with complementary arthrodesis. At L 3-L4, intervertebral slipping also worsened more in the arthrodesis patient s. Use of osteosynthesis significantly increased the risk of developing suc h radiological lesions. These lesions were associated, solely in the arthro desis group, with poorer functional outcome. Conclusion Our findings allow the conclusion that, despite the effect of physiological aging, the observed long-term degenerative lesions in patients undergoing treatment of lumbar stenosis are related to the associated arthrodesis whic h increases their frequency and severity, deteriorating the functional outc ome.