General Session: Cervical Motion Preservation

Presented by: S.B. Park - View Audio/Video Presentation (Members Only)

Author(s):

S.B. Park(1), C.K. Chung(2), C.H. Kim(2)

(1) Seoul National University Boramae Hospital, Seoul, Korea, Republic of
(2) Seoul National University Hospital, Seoul, Korea, Republic of

Abstract

Background: The cervical artificial disc replacement (ADR) provides the preservation of neck motion through reproducing the similar biomechanics at implanted segment. However, there was no clinical study with biomechanical effect on vertebral body of implanted segments except heterotopic ossification after cervical ADR.

Purpose: To evaluate the effects of cervical ADR on the vertebral body of implanted segments using analysis of the change of the body shape on X-ray imaging.

Study Design: Retrospective study.

Methods: The cohort consisted of 35 patients who undergone single-level cervical ADR alone (24 patients) or single-level cervical ADR with anterior cervical discectomy and fusion (ACDF) in adjacent level (11 patients) for degenerative radiculopathy, who did not have any previous spine surgery, and who had a minimum follow-up of 2 years. Whole-spine and cervical lateral radiographs were taken at the preoperative and follow-up consultations. To find the presence of bony remodeling and the significant factors related with the bony remodeling at the implanted level after cervical ADR, the change of shapes of anterior surface and vertebral edges at implanted level, age, sex, bone mineral density, subsidence, adjacent segment degeneration, the combination surgery as ACDF, global cervical lordosis, lordosis at implanted level, and sagittal balance were measured each time. The mean age and follow-up durations of patients were 44 ± 10.6 years and 39 ± 14.4 months, respectively.

Results: The incidence of bony remodeling was 82.9% (29/35). Among cases with the bony remodeling, 23 cases (79.3%, 23/29) and 14 cases (48.2%, 14/29) had edge and anterior surface remodeling at the vertebral body of implanted segment, respectively. Among the considered factors, the preoperative and postoperative lordosis in the patients without the remodeling increased significantly more than those with remodeling (p = 0.012 and 0.011). There was no significant difference in comparison of other factors.

Conclusion: The bony remodeling as the changes of anterior surface and vertebral edge occurs frequently at the implanted vertebrae after cervical ADR. The preservation of global cervical lordosis at the preoperative and last follow-up periods may be important to prevent the bony remodeling after cervical ADR.