The Role of the Main Risk Factors in the Early Adjacent Segment Disease Development in Patients after Lumbar Fusion

Object. To identify the importance of main risk factors of early development of degenerative changes in adjacent spinal mo- tion segments after the lumbar fusion. Material and Methods. The study evaluated the treatment results in 354 patients who underwent fusion in the lumbar spine for degenerative-dystrophic disease. Two groups were compared: Group I included 26 patients with clinically significant adjacent segment disease (ASD) which developed during the first year after surgery, and Group II – 24 patients in whom ASD was identified at a later date. Results. Significant degenerative changes in the overlying intervertebral disc (Pfirrmann grade 4 and higher) were found preoperatively in 16 (61.5 %) patients in Group I. In Group II, such degenerative changes were observed in 3 (12.5 %) pa- tients. Besides, patients in Group I had higher mean index of the difference between pelvic inclination and lumbar lordosis (PI-LL), than patients in Group II (12.2° and 9.3°, respectively). Nine patients in Group I with Pfirrmann grade 4 to 8 de- generative changes demonstrated sagittal imbalance as Positive in 7 cases and Very Positive in 2 cases, according to Schwab classification. Conclusion. Decompensation of the pre-existing degenerative changes in the conditions of increased load after fusion is cru- cial in early development of the adjacent segment disease. Patients with degenerative changes in the adjacent levels of grade 4 and higher according to Pfirrmann, as well as patients with PI-LL index more than 11° have a significantly higher risk of early ASD development.