Clinical and radiological outcomes of cervical disc arthroplasty: ten year follow-up study.

PURPOSE: Previous studies have demonstrated that cervical disc arthroplasty has favourable short- and medium-term clinical and radiological outcomes. However, long-term follow-up outcomes have rarely been reported. The purpose of this study was to evaluate the ten year follow-up clinical and radiological outcomes in patients who underwent Bryan cervical disc arthroplasty.

METHODS: Seventy-one patients who underwent single-level Bryan cervical disc arthroplasty with a minimum ten year follow-up were included in the study. Japanese Orthopaedic Association (JOA) score, neck disability index (NDI), and Odom's criteria were used to evaluate clinical outcomes. X-ray, CT, and MRI were used to evaluate the radiological outcomes.

RESULTS: At last follow-up, the JOA score and NDI improved significantly, and 65 patients (91.5%) had good or excellent outcomes according to Odom's criteria. The range of motion (ROM) at operated level was 9.7° pre-operatively and maintained to 8.6° at last follow-up. The sagittal alignment of operated level was decreased from 2.1° pre-operatively to 1.2° at last follow-up (P < 0.01). The ROM and sagittal alignment of cervical spine had no significant change. At last follow-up, 16 patients (22.5%) developed segmental kyphosis, and 33 patients (46.5%) developed adjacent segment degeneration. Paravertebral ossification (PO) was observed in 66 patients (93.0%), and high-grade PO (grades III and IV) was observed in 25 patients (35.2%).

CONCLUSIONS: The clinical and radiological outcomes of Bryan cervical disc arthroplasty over ten years follow-up are satisfying. However, the occurrence of high-grade PO restricted the ROM of operated level.