Mei-Yin Yeh1, Chao-Hung Kuo2, Jau-Ching Wu3, Wen-Cheng Huang4, Tsung-Hsi Tu5, Li-Yu Fay6, Ching-Lan Wu7, Henrich Cheng6. 1. Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan. 2. Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Neurological Surgery, University of Washington, Seattle, Washington, USA. 3. Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan. 4. Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan. Electronic address: wchuang518@gmail.com. 5. Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Molecular Medicine Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan. 6. Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan. 7. School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan.
Abstract
BACKGROUND: The nonfusion pedicle-screw system Dynesys stabilization (DS) for lumbar degenerative disease aims to better preserve range of motion (ROM) than fixation and fusion systems. However, decreased ROM and unexpected facet fusion at the index level were observed after DS was applied with unknown etiology. The aim of this study is using radiologic parameters to explain the phenomenon of facet arthrodesis. METHODS: The patients who underwent surgery for L4-5 spinal stenosis were sorted retrospectively into 2 groups: DS and microdiskectomy (MicD). Radiologic parameters including facet degeneration, evaluated by computed tomography or magnetic resonance image, and ROM, evaluated by dynamic radiographs, were compared perioperatively. A linear regression model was fitted to data points to calculate correlation over time. Postoperative facet arthrodesis at the index level was detected by computed tomography. Functional outcomes were also compared between groups. RESULTS: A total of 61 patients (DS-to-MicD = 38:23) were followed 36.9 ± 16.8 months postoperatively. After surgery, both groups of patients had significant clinical improvement without difference between the 2 groups (all P > 0.05). In the DS group, significantly decreased ROM was observed after 24-month follow-up (P < 0.05). The correlation coefficient of facet degeneration over time and the facet fusion rate in the DS group were both significantly higher than in the MicD group (both P < 0.05). CONCLUSIONS: The patients who underwent DS for L4-5 grade 1 spondylolisthesis experienced significantly reduced ROM and a positive correlation of facet degeneration over time postoperatively. The limited ROM at the index level could be a potential risk of facet degeneration and cause unexpected arthrodesis.
BACKGROUND: The nonfusion pedicle-screw system Dynesys stabilization (DS) for lumbar degenerative disease aims to better preserve range of motion (ROM) than fixation and fusion systems. However, decreased ROM and unexpected facet fusion at the index level were observed after DS was applied with unknown etiology. The aim of this study is using radiologic parameters to explain the phenomenon of facet arthrodesis. METHODS: The patients who underwent surgery for L4-5 spinal stenosis were sorted retrospectively into 2 groups: DS and microdiskectomy (MicD). Radiologic parameters including facet degeneration, evaluated by computed tomography or magnetic resonance image, and ROM, evaluated by dynamic radiographs, were compared perioperatively. A linear regression model was fitted to data points to calculate correlation over time. Postoperative facet arthrodesis at the index level was detected by computed tomography. Functional outcomes were also compared between groups. RESULTS: A total of 61 patients (DS-to-MicD = 38:23) were followed 36.9 ± 16.8 months postoperatively. After surgery, both groups of patients had significant clinical improvement without difference between the 2 groups (all P > 0.05). In the DS group, significantly decreased ROM was observed after 24-month follow-up (P < 0.05). The correlation coefficient of facet degeneration over time and the facet fusion rate in the DS group were both significantly higher than in the MicD group (both P < 0.05). CONCLUSIONS: The patients who underwent DS for L4-5 grade 1 spondylolisthesis experienced significantly reduced ROM and a positive correlation of facet degeneration over time postoperatively. The limited ROM at the index level could be a potential risk of facet degeneration and cause unexpected arthrodesis.