[Effectiveness of nano-hydroxyapatite/polyamide 66 cage in anterior spinal reconstruction: a mid-term study]

To evaluate the mid-term effectiveness of nano-hydroxyapatite/polyamide66 (n-HA/PA66) cage in the anterior spinal reconstruction.

There were 177 patients who undergone the anterior decompression and fusion with n-HA/PA66 cage and internal fixation between January 2008 and January 2010 included in this study. There were 117 male and 60 female patients aged from 18 to 74 years. The diagnoses included cervical fracture in 47 patients, thoracic or lumbar fracture in 50 patients, cervical spondylopathy in 58 patients, spinal tuberculosis in 17 patients and spinal tumor in 5 patients. The X-ray and three-dimensional CT were followed up in all these patients to observe the spinal alignment, the rate of fusion and the rate of n-HA/PA66 cage subsidence and translocation. The neurological functions of patients with spinal fracture were evaluated by Frankel grading; the improvement of the clinical symptoms of the other patients were assessed by visual analogue scale (VAS) scores and Japan Orthopaedic Association (JOA) scores or SF-36 scores.

All the 177 patients had been followed-up for 36 to 70 months after surgery (average 51 months). Except the slight cage translocation been found in the only one patient with cervical fracture, no cage prolapsed or breakage was exist in our patients up to the last follow-up. In the patients with spinal fracture, the mean time for fusion was 4.5 months, the rate of fusion was 95.9% and the rate of cage subsidence was 5.2%; while in the patients with cervical spondylopathy, the mean time for fusion was 4.4 months, the fusion rate was 96.5% and the subsidence rate was 5.2%; while in patients with spinal tuberculosis, the mean fusion time was 5.5 months, the rate of fusion was 94.0%, the rate of subsidence was 5.9%; and in the patients with tumor, the mean time for fusion was 6.0 months, the fusion rate was 100%, and the cage subsidence was found in only one patient. The preoperative symptoms of each patient were improved to varying degrees after surgery. At the last follow-up, the Frankel grading of patients of spinal fracture with incomplete paralysis improved 0 to 2 classes; the VAS, JOA or SF-36 scores of the other patients were improved significantly than their respective scores before surgery (t = 2.982, 4.126 and 3.980, P < 0.05).

The n-HA/PA66 cage has much higher rate of osseous fusion and lower cage subsidence, it is an ideal cage which can provide effective restoring and maintaining for the spinal alignment and intervertebral height. Moreover, the mid-term clinical results of anterior reconstruction with this cage in the patients with spinal trauma, degeneration, tuberculosis or tumor are well content.