Effects of short anterior lumbar interbody fusion on biomechanics of neighboring unfused segments

Hung Kay Daniel CHOW, Keith D. K. LUK, John H. EVANS, John C. Y. LEONG

Research output: Contribution to journalArticle

202 Citations (Scopus)

Abstract

Study Design. Segmental mobility and intradiscal pressure were measured and the data compared in six cadaveric lumber spine specimens before and after in vitro simulated single level L4-5 and double level L4-5-S1 anterior interbody fusions. 

Objective. The experimental objective was to study the biomechanical effects of single level L4-5 and double level L4-5-S1 anterior interbody fusions on the neighboring unfused segments. 

Summary of Background Data. The relationship between the local rigidity created by fusion mass and accelerated degeneration reported at the neighboring unfused intervertebral discs is not clear. 

Methods. Six cadaveric lumbar spine specimens were biomechanically tested in flexion and extension. Segmental mobility and intradiscal pressure of the specimens were measured before and after in vitro simulation of single level L4-5 and double level L4-5-S1 anterior interbody fusions. 

Results. The mobility of the motion segments immediately above end below an L4-5 fusion was increased in flexion. When the L5-S1 segment was also fused, the loss of segmental motion in both flexion and extension at the L4-5 and L5-S1 were compensated for by increased motion in all levels above the fusion. In both flexion and extension, the intradiacal pressures of all unfused intervertebral discs were increased after a single level L4-5 fusion and this increase was even more marked after a double level L4-5-S1 fusion. 

Conclusions. There is no evidence that the neighboring unfused segments are loaded beyond their physiological limits due to the fusion. However, the neighboring unfused segments have to work more frequently toward the extremes of their functional ranges of motion after fusion and these effects will be more marked after a double level L4-5-S1 fusion. Copyright © 1996 Lippincott-Raven Publishers.

Original languageEnglish
Pages (from-to)549-555
JournalSpine
Volume21
Issue number5
DOIs
Publication statusPublished - 01 Mar 1996

Fingerprint

Biomechanical Phenomena
Intervertebral Disc
Pressure
Spine
Articular Range of Motion
In Vitro Techniques

Citation

Chow, D. H. K., Luk, K. D. K., Evans, J. H., & Leong, J. C. Y. (1996). Effects of short anterior lumbar interbody fusion on biomechanics of neighboring unfused segments. Spine, 21(5), 549-555. doi: 10.1097/00007632-199603010-00004

Keywords

  • Biomechanical study
  • Kinematics
  • Interbody fusion
  • Neighboring segments