gms | German Medical Science

54. Jahrestagung der Norddeutschen Orthopädenvereinigung e. V.

Norddeutsche Orthopädenvereinigung

16.06. bis 18.06.2005, Hamburg

ALIF versus PLIF: a Roentgen Stereometric Analysis (RSA) of spinal arthrodesis

Meeting Abstract

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  • corresponding author J. Jung - Department of Orthopedic Surgery, Saarland University Medical Center, Homburg, Germany, Orthopädie, Homburg / Saar
  • D. Pape - Homburg
  • E.W. Fritsch - Homburg

Norddeutsche Orthopädenvereinigung. 54. Jahrestagung der Norddeutschen Orthopädenvereinigung e.V.. Hamburg, 16.-18.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05novW2.03

The electronic version of this article is the complete one and can be found online at:

Published: June 13, 2005

© 2005 Jung et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.




Spinal fusion with an internal fixator and insertion of interbody cages is an established method, although surgical approach and cage design are disputed. Interbody cages are said to maintain disc height depending on cage design, presence of supplementary posterior fixation and mineral bone density. Using the precise RSA method, stability of the fused segments in patients with spinal stenosis and spondylolisthesis were prospectively investigated.

Materials and Methods

8 patients with spinal stenosis L4/5 underwent a one-stage posterior decompression and stabilization with 2 rectangle carbon-fibre Brantigan PLIF-cages. 8 patients with low-grade spondylolisthesis L5/S1 underwent a two-stage posterior and retroperitoneal anterior fusion with insertion of an oval-shaped carbon-fibre Brantigan ALIF-cage. At surgery, tantalum markers were implanted into the adjacent vertebrae. All patients were examined by RSA after the first/second operation and every 3 months.


3 month after surgery the mean intervetebral mobility determined by RSA was below the accuracy of the RSA-method (3/10 mm). Within the first 6 month after surgery, ALIF-cages showed a mean subsidence of 0.9 mm along the vertical axis. PLIF-cages showed a significant ongoing settlement of 1.4 mm on average within the first 12 months after surgery. Both cages showed persisting micomotions in the direction of insertion.


Although bony fusion could be achieved with both cages 3 month after surgery, settling around PLIF-cages persisted longer compared to ALIF-cages. The smaller contact area of the bone-implant interface in the PLIF-procedure might lead to higher axial compression forces promoting the persisting subsidence of PLIF-cages.