title: Dynesys dynamic stabilization-related facet arthrodesis.
abstract: OBJECTIVE Dynamic stabilization devices are designed to stabilize the spine while preserving some motion. However, there have been reports demonstrating limited motion at the instrumented level of the lumbar spine after Dynesys dynamic stabilization (DDS). The causes of this limited motion and its actual effects on outcomes after DDS remain elusive. In this study, the authors investigate the incidence of unintended facet arthrodesis after DDS and clinical outcomes. METHODS This retrospective study included 80 consecutive patients with 1- or 2-level lumbar spinal stenosis who underwent laminectomy and DDS. All medical records, radiological data, and clinical evaluations were analyzed. Imaging studies included pre- and postoperative radiographs, MR images, and CT scans. Clinical outcomes were measured by a visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and Japanese Orthopaedic Association (JOA) scores. Furthermore, all patients had undergone postoperative CT for the detection of unintended arthrodesis of the facets at the indexed level, and range of motion was measured on standing dynamic radiographs. RESULTS A total of 70 patients (87.5%) with a mean age of 64.0 years completed the minimum 24-month postoperative follow-up (mean duration 29.9 months). Unintended facet arthrodesis at the DDS instrumented level was demonstrated by CT in 38 (54.3%) of the 70 patients. The mean age of patients who had facet arthrodesis was 9.8 years greater than that of the patients who did not (68.3 vs 58.5 years, p = 0.009). There were no significant differences in clinical outcomes, including VAS back and leg pain, ODI, and JOA scores between patients with and without the unintended facet arthrodesis. Furthermore, those patients older than 60 years were more likely to have unintended facet arthrodesis (OR 12.42) and immobile spinal segments (OR 2.96) after DDS. Regardless of whether unintended facet arthrodesis was present or not, clinical evaluations demonstrated improvement in all patients (all p < 0.05). CONCLUSIONS During the follow-up of more than 2 years, unintended facet arthrodesis was demonstrated in 54.3% of the patients who underwent 1- or 2-level DDS. Older patients (age > 60 years) were more likely to have unintended facet arthrodesis and subsequent immobile spinal segments. However, unintended facet arthrodesis did not affect the clinical outcomes during the study period. Further evaluations are needed to clarify the actual significance of this phenomenon.
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;|Faculty of Medicine, School of Medicine and.|Institute of Pharmacology, National Yang-Ming University;
authors.forename: Li-Yu
authors.initials: LY
authors.lastname: Fay
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;|Faculty of Medicine, School of Medicine and.
authors.forename: Peng-Yuan
authors.initials: PY
authors.lastname: Chang
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;|Faculty of Medicine, School of Medicine and.|Institute of Pharmacology, National Yang-Ming University;
authors.forename: Jau-Ching
authors.initials: JC
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;|Faculty of Medicine, School of Medicine and.
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Huang
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;|Faculty of Medicine, School of Medicine and.
authors.forename: Chun-Hao
authors.initials: CH
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, National Taiwan University Hospital and College of Medicine, National Taiwan University;|Ophthalmology Department, Far Eastern Memorial Hospital, New Taipei City, Taiwan.
authors.forename: Tzu-Yun
authors.initials: TY
authors.lastname: Tsai
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;|Faculty of Medicine, School of Medicine and.
authors.forename: Tsung-Hsi
authors.initials: TH
authors.lastname: Tu
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;|Faculty of Medicine, School of Medicine and.
authors.forename: Hsuan-Kan
authors.initials: HK
authors.lastname: Chang
authors.affiliation: Faculty of Medicine, School of Medicine and.|Department of Radiology, Taipei Veterans General Hospital, Taipei; and.
authors.forename: Ching-Lan
authors.initials: CL
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;|Faculty of Medicine, School of Medicine and.|Institute of Pharmacology, National Yang-Ming University;
authors.forename: Henrich
authors.initials: H
authors.lastname: Cheng
mesh_terms: D000328:Adult; D000368:Aged; D001174:Arthrodesis / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods*; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000601:surgery*; D021801:Zygapophyseal Joint / Q000601:surgery*
keywords: ASD = adjacent-segment disease; DDS = Dynesys dynamic stabilization; Dynesys; JOA = Japanese Orthopaedic Association; ODI = Oswestry Disability Index; ROM = range of motion; VAS = visual analog scale; arthrodesis; dynamic stabilization; facet joints; lumbar spondylosis