gms | German Medical Science

54. Jahrestagung der Norddeutschen Orthopädenvereinigung e. V.

Norddeutsche Orthopädenvereinigung

16.06. bis 18.06.2005, Hamburg

Influence of cage geometry on sagittal alignment in polysegmental instrumented PLIF

Meeting Abstract

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  • corresponding author S. Gödde - Universitätsklinikum des Saarlandes, Orthopädische Universitäts- und Poliklink, Homburg/Saar
  • E.W. Fritsch - Homburg/Saar
  • D. Kohn - Homburg/Saar

Norddeutsche Orthopädenvereinigung. 54. Jahrestagung der Norddeutschen Orthopädenvereinigung e.V.. Hamburg, 16.-18.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05novW4.02

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

Published: June 13, 2005

© 2005 Gödde 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.




The study was conducted to determine the influence of the cage geometry on the sagittal alignment of the lumbar spine in polysegmental instrumented PLIF.

Patients and Methods

41 patients having undergone instrumented polysegmental PLIF between L2 and S1 were reviewed retrospectively. 21 patients had PLIF with rectangular cages (RC): 10 double- and 11 tripple-level fusions. 20 patients had PLIF with wedge shaped cages (WSC): 9 double- and 11 tripple-level fusions. All patients had additional pedicle screw fixation, the operative technique was standardized. Pre- and postoperative standing lateral radiographs were assessed for segmental and lumbar lordosis, lumbar and sacral tilt.


Mean follow up was 22 months. Preoperatively there were no significant differences between the two groups. Mean segmental lordosis of fused segments showed significant differences between the two

groups (P<0,05). Segmental lordosis decreased after fusion surgery in the RC group at all levels and increased in the WSC group at all levels. Analysis of the other parameters showed opposite trends: Lumbar lordosis and sacral tilt decreased in the RC group and increased in the WSC group. Lumbar tilt increased in the RC group whereas it decreased in the WSC group.


The cage geometry has a significant impact on the alignment. With rectangular cages lumbar lordosis and segmental lordosis of the segments fused decrease, sagittal balance is maintained by compensatory changes of the sacral tilt. Wedge shaped cages significantly increase segmental lordosis, enhance lumbar lordosis and therefore should be preferred for restoring sagittal alignment in instrumented PLIF procedures.