Cervical Alignment After Cervical Arthroplasty with Prestige-LP Disc at C5-C6 Level

OBJECTIVE: We explored the effects of implantation of the Prestige-LP disc at the C5-C6 level on cervical alignment and the association between the cervical alignment and clinical outcomes. METHODS: Patients with C5-C6 level cervical disc arthroplasty were consecutively reviewed. The Japanese Orthopaedic Association score, neck disability index, visual analog scale (VAS) for neck pain, and VAS for arm pain were used to evaluate the clinical outcomes. The range of motion (ROM) and cervical alignment, including the C2-C7 angle and C5-C6 angle, were measured. RESULTS: Seventy-seven patients were included, with a mean follow-up of 42.6 months. Most patients achieved a significant reduction in VAS scores and the neck disability index but had a significant increase in the Japanese Orthopaedic Association scores. The C5-C6 ROM, C2-C7 ROM, and C2-C7 angle were preserved and the C5-C6 angle had changed significantly. The C2-C7 angle increased significantly from 15.2 degrees +/- 11.5 degrees preoperatively to 19.4 degrees +/- 10.2 degrees at the 12-month follow-up visit (P < 0.001) and had decreased to 16.8 degrees +/- 10.4 degrees at the last follow-up visit (P = 0.45). The C5-C6 angle had increased significantly from 0.07 degrees +/- 5.2 degrees preoperatively to 2.8 degrees +/- 5.8 degrees at the 3-month follow-up visit (P < 0.001) and had stabilized at 2.2 degrees +/- 5.8 degrees at the last measurement (P = 0.003). No significant correlation was found between the C2-C7 angle and the clinical outcomes. A significant correlation was found between the C5-C6 angle and VAS score for arm pain (r = -0.38; P = 0.02). CONCLUSIONS: The C2-C7 angle was preserved and the C5-C6 angle was restored to lordosis after cervical disc arthroplasty. It seems that segmental lordosis was associated with less arm pain.