Outcome of single level anterior cervical discectomy and fusion using nano-hydroxyapatite/polyamide-66 cage

Background: Cages have been widely used for the anterior reconstruction and fusion of cervical spine. Nonmetal cages have become popular due to prominent stress shielding and high rate of subsidence of metallic cages. This study aims to assess fusion with n-HA/PA66 cage following one level anterior cervical discectomy. Materials and Methods: Forty seven consecutive patients with radiculopathy or myelopathy underwent single level ACDF using n-HA/PA66 cage. We measured the segmental lordosis and intervertebral disc height on preoperative radiographs and then calculated the loss of segmental lordosis correction and cage subsidence over followup. Fusion status was evaluated on CT scans. Odom criteria, Japanese Orthopedic Association (JOA) and Visual Analog Pain Scales (VAS) scores were used to assess the clinical results. Statistically quantitative data were analyzed while Categorical data by chi(2) test. Results: Mean correction of segmental lordosis from surgery was 6.9 +/- 3.0 degrees with a mean loss of correction of 1.7 +/- 1.9 degrees. Mean cage subsidence was 1.2 +/- 0.6 mm and the rate of cage subsidence (>2 mm) was 2%. The rate of fusion success was 100%. No significant difference was found on clinical or radiographic outcomes between the patients (n=27) who were fused by n-HA/PA66 cage with pure local bone and the ones (n=20) with hybrid bone (local bone associating with bone from iliac crest). Conclusions: The n-HA/PA66 cage is a satisfactory reconstructing implant after anterior cervical discectomy, which can effectively promote bone graft fusion and prevent cage subsidence.