Influence of an artificial cervical joint compared with fusion on adjacent-level motion in the treatment of degenerative cervical disc disease.
OBJECTIVE
The authors report the preservation of motion at surgically treated and adjacent spinal segments after placing an artificial cervical joint (ACJ) and they describe the influence of interbody fusion on changes in angulation occurring in the sagittal plane at adjacent levels in the treatment of cervical spondylosis.


METHODS
The authors conducted a prospective nonrandomized study of patients in whom an ACJ was placed or autologous bone graft interbody fusion was performed. Angular measurements at levels adjacent to that surgically treated were calculated using plain flexion-extension radiographs obtained at 6-month intervals. Analyses of qualitative data, such as increase or decrease in adjacent-level motion, and the degree of disc degeneration were performed. Quantitative data were also analyzed. In the fusion group a significant increase in adjacent-level movement was demonstrated at the 12-month follow-up visit compared with the group of patients in whom ACJs were placed (p < 0.001). The increase in movement occurred predominantly at intervertebral discs that were preoperatively regarded as normal (p < 0.02). An overall reduction in adjacent-level movement was observed in patients who underwent joint replacement, although this was compensated for by the movement provided by the ACJ itself.


CONCLUSIONS
Fusion results in increased motion at adjacent levels. The increase in adjacent-level motion derives from those discs that appear radiologically normal prior to surgery. It remains unknown whether ACJs have a protective influence on adjacent intervertebral discs.
Wigfield
Crispin
C
cagincourt@cs.com
Gill
Steven
S
Nelson
Richard
R
Langdon
Ilana
I
Metcalf
Newton
N
Robertson
James
J
D000328:Adult; D000368:Aged; D016025:Bone Transplantation; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011446:Prospective Studies; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D013123:Spinal Fusion; D013128:Spinal Osteophytosis / Q000000981:diagnostic imaging / Q000601:surgery*