Comparison of mechanical motion profiles following instrumented fusion and non-instrumented fusion at the L4-5 segment.
OBJECTIVE
To investigate the difference in motion profiles between instrumented and non-instrumented fusion of the lumbar spine.


METHODS
In vivo retrospective radiological analysis of dynamic (flexion-extension) lateral plain films was performed in different lumbar spine fusion types. Twenty-eight patients underwent lumbar fusion surgery at the L4/5 level. Fourteen patients underwent anterior fusion surgery without implantation, and the others underwent posterior instrumented fusion. Segmental angular motion was measured at the fused and adjacent levels using dynamic plain lateral film 2 years after operation.


RESULTS
The anterior uninstrumented fusion group showed mean 2.0 degrees of segmental angular motion at the fused level compared with mean of 0.8 degrees in the posterior instrumented fusion group (P < 0.05). In contrast, at the proximal adjacent level, decreased angular motion (mean 7.7 degrees ) was noted in the anterior uninstrumented fusion group compared with mean 11.6 degrees in the posterior instrumented fusion group (P < 0.05).


CONCLUSIONS
This study suggests that differing stiffness of fusion segments could cause different mechanical motion profiles at adjacent segments.
Kim
Ho-Joong
HJ
Department of Orthopaedic Surgery, Yonsei University, Seoul, Korea.
Moon
Seong-Hwan
SH
Chun
Heoung-Jae
HJ
Kang
Kyoung-Tak
KT
Kim
Hak-Sun
HS
Moon
Eun-Su
ES
Park
Jin-Oh
JO
Hwang
Byung-Yoon
BY
Lee
Hwan-Mo
HM
D000328:Adult; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D013123:Spinal Fusion