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Surgical and Radiologic Anatomy
https://doi.org/10.1007/s00276-018-2048-7
ORIGINAL ARTICLE
Magnetic resonance morphometry of the adult normal lumbar
intervertebral space
Apostolos H. Fyllos
1,2
· Dimitrios L. Arvanitis
1
· Apostolos H. Karantanas
3
· Sokratis E. Varitimidis
2
·
Michael Hantes
2
· Aristeidis H. Zibis
1
Received: 22 September 2017 / Accepted: 1 June 2018
© Springer-Verlag France SAS, part of Springer Nature 2018
Abstract
Purpose This study aims to: (a) quantify and evaluate normal relationships between neighboring spinal units using MR
imaging indices, (b) propose an easy-to-apply-and-reproduce method of estimating the correct amount of distraction when
surgically restoring a collapsed intervertebral disc, based on individualized measurements.
Methods This is a retrospective cross-sectional MR imaging study of 119 adult subjects, aged 18–54, asymptomatic for low
back pain. Each of the examinees should demonstrate two or more consecutive intervertebral discs classified as Pfirrmann
grade I or II to be included. We measured and studied the relationships of disc height index, Dabbs index, Farfan index, disc
convexity index and mean and posterior disc height per spinal level using multiple regression analysis. All measurements
were tested for intra- and interobserver agreement by two raters.
Results DHI, Dabbs, Farfan, and mean disc height had a statistically significant correlation with the spinal level and age.
Our results were highly reproducible, with excellent inter- and intraobserver agreement and reliability between two raters
(ICC = 0.992 and 0.994, respectively). Furthermore, we expressed each intervertebral space as a percentage of its adjacent
space, introducing the coefficient α factor for every intervertebral space.
Conclusions Our results suggest that a normal values’ database to refer during preoperative planning of correction of a
degenerated intervertebral disc is feasible. Our study offers new anatomical and radiological insight in terms of spinal
measurements and their potential correlation with current surgical techniques. A new approach for calculating disc space as
an expression of its adjacent disc has been introduced with various potential applications.
Keywords Intervertebral disc · Spine · Magnetic resonance imaging · Anatomy
Introduction
Degenerative alterations in spinal anatomy over time cor-
relate with new-onset symptomatology that ranges from
annoying to crippling. When conservative treatment no
longer relieves pain, surgical therapeutic interventions
have been developed that aim at restoring normal spinal
relationships and function. Fusion is performed with struc-
tural constructs using mostly interbody cages in the disc
space. Selecting an interbody cage with appropriate height
is one of the key steps in lumbar interbody fusion, and
has an important impact on clinical efficacy. An oversized
cage leads to over distraction of intervertebral space and
it might also increase possibility for injury to the nerve
roots. Using a small fusion cage, on the other hand, will
fail to restore the intervertebral height and lordosis, and
may lead to severe complications such as cage migration
and fusion failure, but the interbody cage height or perio-
perative distraction has long been determined by surgeons
mostly based on their operational experience [30]. Another
surgical option for patients with degenerative disc disease
at a single level is total disc replacement (TDR), where
intervertebral distraction is also part of the surgical tech-
nique. Postoperative complications due to insufficient
* Aristeidis H. Zibis
ahzibis@gmail.com
1
Department of Anatomy, School of Medicine, University
of Thessaly, Panepistimiou 3 (Biopolis), 41110 Larissa,
Greece
2
Department of Orthopedics, University Hospital of Larisa,
41110 Larissa, Greece
3
Department of Radiology, School of Medicine, University
of Crete, 71110 Heraklion, Greece
@Phil_Robichaud
@deepthiw
@JoseServera