Comparative analysis of clinical outcomes between zero-profile implant and cages with plate fixation in treating multilevel cervical spondilotic myelopathy: A three-year follow-up.

OBJECTIVES: This study aimed to figure out three-year clinical outcomes and complications of ACDF with Zero-p in treating multilevel cervical spondylotic myelopathy (MCSM) by comparing with plate fixation.

CLINICAL MATERIALS AND METHODS: Patients with MCSM caused by degenerative disc herniation only were recruited from April 2010 to December 2010. According to the surgical procedures, the patients were divided into two groups at random, the plate group and Zero-P group. The data was collected before surgery and at three-year follow-up. Clinical parameters, including Japanese orthopedic association (JOA) score, neck disabled index (NDI) were evaluated. Cervical segmental lordosis was calculated and fusion in each level was assessed on lateral radiographs. The Bazaz's criterion and the short Swallowing and Quality of Life (SQOL) questionnaires were used to evaluate the dysphagia incidence and severity respectively. The presence of ALOD was observed and recorded on lateral radiographs.

RESULTS: A total of 72 patients (46 men and 26 women) were recruited. The mean age at operation was 52.9±7.9years, ranged from 43 to 69 years. There was no significant difference between two groups preoperatively in age, sex, operative levels, JOA, NDI, cervical lordosis, dysphagia incidence, SQOL and ALOD incidence. JOA, NDI and cervical lordosis improved postoperatively and postoperative SQOL got restitution in both groups. However, no difference was detected. There were 7 patients with ALOD in the plate group after surgeries while there was only 1 patient in Zero-P group. The difference of AOLD incidence between them was significant. Of the 7 patients with ALOD in the plate group, 4 patients developed ALOD in cranial level, 2 in caudal level and 1 in both levels. The patient in Zero-P group developed ALOD in caudal level.

CONCLUSION: Based on the three-year follow-up, we could not conclude that Zero-P was superior to plate fixation in clinical outcomes such as neurological results, cervical lordosis, fusion rate and the incidence and severity of dysphagia in treating MCSM. However, it had the advantage of reducing ALOD incidence which tended to happen in ACDF with plate fixation.