Abstract
Introduction
The use of artificial disc replacement of cervical spine (C-ADR) has been advocated to preserve segmental motion and to prevent adjacent segment disease as an alternative to anterior cervical discectomy fusion (ACDF). Previous studies reported satisfactory clinical and radiological outcomes of C-ADR compared with ACDF. However, some patients with C-ADR undergo revision surgeries due to failure of C-ADR, such as persistence or recurrence of symptoms and complications. Therefore, we performed the current study to investigate causes and results of revision surgeries following C-ADR.
Material and Methods
Twenty-one patients (13 males and 8 females) were treated with revision surgeries for failure of C-ADR and had a minimum 2-year follow-up. Causes for revision surgeries were at least one of the following: 17 poor patient selections (severe spondylosis), 7 insufficient decompressions, 7 malpositions, 6 subsidences, 3 osteolysis, and 1 infection. The mean age was 52.8 years (range, 43–63 years) and mean time to revision surgery was 21 months (range, 4–84 months). During their initial surgeries, 14 patients underwent single-level C-ADR, 2 two-level C-ADR, and 5 two-level hybrid surgery for 16 radiculopathy, 3 myelopathy, and 2 adjacent segment disease. Clinical evaluation was done by neck and arm visual analog scales (VAS) and Neck Disability Index (NDI) score. Fusion status was evaluated by plain radiographs including flexion and extension lateral radiographs. Follow-up measurements were taken before surgery and postoperatively at 1, 3, 6, and 12 months, 24 months as well as at last follow-up. At the 24-month fololow-up, patients' overall satiafaction and final fusion status were evaluated by Odom's criteria and CT scan, respectively.
Results
Sixteen patients underwent anterior removal of C-ADR (8 MobiC, 4 Discovery, 2 Bryan, 1 Prodisc-C, and 1 Prestige LP), one-level discectomy and fusion with plate (N = 11), two-level discectomy and fusion with plate (N = 3) or corpectomy and two-level fusion with plate (N = 2). Three patients with keel types of C-ADR (2 Prodisc-C and 1 Prestige LP) and extensive heterotopic ossification were treated by laminoforaminotomy with posterior fusion. Two patients (2 Discovery) with kyphosis and severe bone loss due to infection or severe subsidence were treated by combined anterior and posterior approaches. NDI score and neck and arm VAS were improved after revision surgeries at each time point of follow-up. At the 24 months of follow-up, 86% (N = 18) of the patients was satisfied and 91% (N = 19) achieved solid fusion. However, 2 patients with pseudoarthrosis did not have sufficient pain to warrant the operative repair of the psuedoarthrosis. No major neurologic and wound complications were developed except transient dysphagia in 6 patients with mean recovery time of 1.7 months (range, 1–4 months).
Conclusion
Revision surgeries can provide successful outcomes in failure of C-ADR without major neurologic and wound complications. Our results suggest that careful patient selection and meticulous surgical techniques, such as adequate decompression, proper positioning of C-ADR, and preservation of subchondral bone, are important to avoid revision surgeries for failure of C-ADR.