Stand-Alone Cervical Cages in 2-Level Anterior Interbody Fusion in Cervical Spondylotic Myelopathy: Results from a Minimum 2-Year Follow-up

STUDY DESIGN: A retrospective review of patients who underwent 2-level anterior cervical discectomy and fusion (ACDF) with standalone polyetheretherketone (PEEK) cages for cervical spondylotic myelopathy (CSM). PURPOSE: To evaluate the efficacy of stand-alone PEEK cage in 2-level cervical interbody fusion for CSM. OVERVIEW OF LITERATURE: ACDF is a standard surgical procedure to treat degenerative disc disease. However, the use of additional anterior plating for 2-level ACDF remains controversial. METHODS: We reviewed outcomes of patients who underwent 2-level ACDF with stand-alone PEEK cages for CSM over a 7-year period (2007–2015) in a regional hospital. Japanese Orthopaedic Association (JOA) score, fusion rate, subsidence rate, cage migration, and cervical alignment by the C2–7 angle as well as the local segmental angle (LSA) of the cervical spine were assessed. RESULTS: In total, 31 patients (mean age, 59 years; range, 36–87 years) underwent 2-level ACDF with a cage-only construct procedure between 2007 and 2015. The minimum follow-up was 24 months; mean follow-up was 51 months. C3–5 fusion was performed in 45%, C4–6 fusion in 32%, and C5–7 fusion in 23%. Mean JOA score improved from 10.1±2.2 to 13.9±2.1 (p<0.01) at the 24-month follow-up. Fusion was achieved in all patients. Subsidence occurred in 22.5% of the cages but was not associated with differences in JOA scores, age, sex, or levels fused. Lordosis of the C2–7 angle and LSA increased after surgery, which were maintained for up to 1 year but subsequently disappeared after 2 years, yet the difference was not statistically significant. No cage migration was noted; two patients developed adjacent segment disease requiring posterior laminoplasty 3 years after ACDF. CONCLUSIONS: The use of a stand-alone PEEK cage in a 2-level cervical interbody fusion achieves satisfactory improvements in both clinical outcomes and fusion.

Two-Level Anterior Cervical Discectomy and Fusion with Stand-alone Cages in Cervical Spinal Degenerative Diseases

OBJECTIVE: Anterior cervical discectomy and fusion(ACDF) is a highly successful surgical treatment for nerve root or spinal cord compression caused by disc herniation or spondylosis. Multilevel cervical discectomy usually requires plate and screw fixation for adequate bony fusion and stability. But the use of plate and screw fixation may cause some post-operative complications. So in this study we evaluate the safety and effectiveness of two-level ACDF with carbon or polyetheretherketone(PEEK) cages without cervical plate in cervical degenerative disc disease. METHODS: We retrospectively analyzed 18 patients who underwent two-level ACDF with carbon or PEEK cages from February 2002 to August 2008. The mean follow-up period was 31months. Clinical, radiologic and surgical morbidities were assessed in all cases. Outcome assessment was done using Odom's criteria and visual analogue scale(VAS) score. Radiological assessment was done with bony fusion rate, linear measure of cervical lordosis, cervical lordotic angle and cage subsidence. RESULTS: Radiculopathy was improved in all cases(100%) after surgery, whereas myelopathy was resolved in three of five patients(60%). Radiographic evidence of fusion was found in all patients(100%) at last follow-up. Preoperative mean VAS score was 8.1 compared with a postoperative score 2.5(p<0.05). The clinical outcome was excellent or good in 16 cases(89%). There were no serious complications such as dislodgement of cages, hardware failure, infection and neurologic deterioration. Linear measure of cervical lordosis at last follow-up was increased from 2.72+/-1.12mm to 7.84+/-1.09mm. Cervical lordotic angle at last follow-up was increased from 8.9+/-2.76 degrees to 15.1+/-2.38 degrees. The mean loss of disc height was 1.40mm during the follow-up period. However development of subsidence did not influence on clinical outcomes. CONCLUSION: ACDF in two-level stand-alone cages is a safe and effective procedure in multilevel cervical degenerative diseases. In spite of subsidence, interbody fusion with cages provides load-sharing function and stabilization of the cervical spine by increasing segmental rigidity, thus yielding excellent fusion rates and less graft failure, even in two- level cervical diseases.