Segmental kinematics and adjacent level degeneration following disc replacement versus fusion: RCT with three years of follow-up.

STUDY DESIGN

Prospective, randomized and controlled clinical and radiological study.

OBJECTIVE

The aim of this study was to assess the segmental kinematics and clinical outcome of disc replacement with ProDisc C versus anterior cervical discectomy and fusion (ACDF) for monosegmental disease 3 years after surgery.

SUMMARY OF BACKGROUND DATA

Anterior cervical discectomy and fusion (ACDF), including plate fixation, is an accepted technique for treatment of symptomatic degenerative disc disease (DDD). However, various studies could show that fusion of a relative mobile spinal segment leads to heightens of stresses on the discs below and above fusion, which is manifested as adjacent level degeneration. Intervertebral disc replacement has been attempted to restore intervertebral disc height and to maintain segmental motion, which may be thought to avoid the accelerated degeneration to the adjacent level. In earlier studies, we could show that ProDisc C could maintain segmental motion for 1 year after surgery.

METHODS

49 patients with cervical disc herniation underwent arthroplasty of a single level using ProDisc C disc prosthesis or received fusion using a cage and anterior titanium plate fixation. Clinical outcome was assessed using the visual analogue scale (VAS) and the neck disability index (NDI). Radiostereometry was performed immediately postoperative and then after 1, 2, and 3 years after surgery to quantify the segmental kinematics.

RESULTS

The range of motion of the treated segment with prosthesis remained unchanged 3 years after surgery in comparison to the 1-year result. The prosthesis shows a significant segmental motion in contrast to the fusion group at each RSA examination time (p < 0.05). After both procedures, a significant pain reduction in neck and arm was observed, without significant differences between both groups. During the course of the 3 years follow-up, no patients of the prosthesis group required further surgical intervention.