Indirect foraminal decompression after lateral transpsoas interbody fusion

Clinical article

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Lateral transpsoas interbody fusion (LTIF) permits anterior column lumbar interbody fusion via a direct lateral approach. The authors sought to answer 3 questions. First, what is the effect of LTIF on lumbar foraminal area? Second, how does interbody cage placement affect intervertebral height? And third, how does the change in foraminal area and cage position correlate with changes in Oswestry Disability Index (ODI) and 12-Item Short Form Health Survey (SF-12) scores?


Included patients underwent LTIF with or without posterior instrumentation and received preoperative and postoperative CT scans. Disc heights, neural foraminal area between adjacent-level pedicles, and anteroposterior cage position were measured from sagittal CT images. Preoperative and postoperative ODI and SF-12 scores were matched with the change in foraminal area from the clinically most severely affected side for analysis of the relationship between outcomes instruments and change in foraminal area.


Average foraminal area increased by 36.2 mm2, or 35% of the preoperative area (p < 0.01), without statistically significant differences by side, level, or anteroposterior cage position. Preoperative anterior and posterior disc heights measured 6.2 mm and 3.7 mm, respectively, compared with postoperative measurements of 9.8 mm (p < 0.01) and 6.3 mm (p < 0.01), respectively, without significant differences by level or cage position. Despite significant overall improvement in ODI and SF-12 scores, there was no correlation with foraminal area increase.


Average foraminal area increased approximately 35% after cage placement without variation based on cage position. While ODI and SF-12 scores increased significantly, there was no significant association with cage position or foraminal area change, likely attributable to the multifactorial nature of preoperative pain.

Abbreviations used in this paperACDF = anterior cervical discectomy and fusion; ICC = intraclass correlation coefficient; LTIF = lateral transpsoas interbody fusion; MCS = mental component subscore; ODI = Oswestry Disability Index; PCS = physical component subscore; PLIF = posterior lumbar interbody fusion; SF-12 = 12-Item Short Form Health Survey; XLIF = extreme lateral interbody fusion.

Article Information

Address correspondence to: Christopher K. Kepler, M.D., M.B.A., Hospital for Special Surgery, 535 East 70th Street, New York, New York 10021. email:

Please include this information when citing this paper: published online January 27, 2012; DOI: 10.3171/2012.1.SPINE11528.

© AANS, except where prohibited by US copyright law.



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    Sagittal CT scan showing the measurement of the postoperative foraminal area by outlining the neural foramen to create a custom shape matching the confines of bone/disc structures.


  • 1

    Albert TJSmith MDBressler EJohnson LJ: An in vivo analysis of the dimensional changes of the neuroforamen after anterior cervical diskectomy and fusion: a radiologic investigation. J Spinal Disord 10:2292331997

    • Search Google Scholar
    • Export Citation
  • 2

    Groth ATKuklo TRKlemme WRPolly DWSchroeder TM: Comparison of sagittal contour and posterior disc height following interbody fusion: threaded cylindrical cages versus structural allograft versus vertical cages. J Spinal Disord Tech 18:3323362005

    • Search Google Scholar
    • Export Citation
  • 3

    Hägg OFritzell PNordwall A: The clinical importance of changes in outcome scores after treatment for chronic low back pain. Eur Spine J 12:12202003

    • Search Google Scholar
    • Export Citation
  • 4

    Ozgur BMAryan HEPimenta LTaylor WR: Extreme Lateral Interbody Fusion (XLIF): a novel surgical technique for anterior lumbar interbody fusion. Spine J 6:4354432006

    • Search Google Scholar
    • Export Citation
  • 5

    Rockoff SDSweet EBleustein J: The relative contribution of trabecular and cortical bone to the strength of human lumbar vertebrae. Calcif Tissue Res 3:1631751969

    • Search Google Scholar
    • Export Citation
  • 6

    Schlegel JDChampine JTaylor MSWatson JTChampine MSchleusener RL: The role of distraction in improving the space available in the lumbar stenotic canal and foramen. Spine (Phila Pa 1976) 19:204120471994

    • Search Google Scholar
    • Export Citation
  • 7

    Steffen TTsantrizos AAebi M: Effect of implant design and endplate preparation on the compressive strength of interbody fusion constructs. Spine (Phila Pa 1976) 25:107710842000

    • Search Google Scholar
    • Export Citation
  • 8

    Wang MDalal SBagaria VBMcGrady LMRao RD: Changes in the lumbar foramen following anterior interbody fusion with tapered or cylindrical cages. Spine J 7:5635692007

    • Search Google Scholar
    • Export Citation



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