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Antenatal Factors in the Development of the Lumbar Vertebral Canal: A Magnetic Resonance Imaging Study

Jeffrey, Janet E., MSc*; Campbell, Doris M., MD, FRCOG; Golden, Michael H. N., FRCP; Smith, Francis W., MD§; Porter, Richard W., MD DSc FRCS, FRCSE*

doi: 10.1097/01.BRS.0000067086.39849.B3

Study Design. The lumbar vertebral canal was measured in two cohorts of 10-year-old children (n = 161) using magnetic resonance imaging (MRI) and compared with obstetric records.

Objective. To investigate whether there are identifiable obstetric factors that determine the size of the lumbar vertebral canal.

Summary of Background Data. The most rapid period growth for the lumbar vertebral canal is between 12 and 32 weeks in utero, with the midsagittal diameter of L1–L4 already 70% of adult dimension at birth. Therefore, adverse antenatal factors during this critical growth period may be expected to affect the size of the canal.

Methods. The canal size was measured from axial MRI sections taken through each lumbar vertebra (L1–L5) at the pedicular level of 84 children. Relations with obstetric data, prospectively collected in a neonatal database, were sought. The relation of low birthweight and canal size was further investigated in a second cohort of children (n = 77).

Results. The canal size, particularly the midsagittal diameter and the cross-sectional area, was found to be significantly reduced by low birthweight (with growth retardation in utero being a more important factor than length of gestation), low placenta weight, and lower socioeconomic class. Smoking during pregnancy significantly reduced the perimeter at L3 (P = 0.032) and L5 (P = 0.031), and also the cross-sectional area at L3 (P = 0.030) and L5 (P = 0.016).

Conclusions. This study showed that, for this group of children, the size of the lumbar vertebral canal was reduced by low birthweight, with maternal smoking as an added adverse factor. Therefore, good antenatal care and maternal education may help to reduce the risk of spinal stenosis in adult life.

From the Departments of *Orthopaedic Surgery,

†Obstetrics and Gynaecology, and

‡Medicine and Therapeutics, University of Aberdeen, Aberdeen, and the

§Department of Radiology, Woodend Hospital, Aberdeen, Scotland.

Supported by BackCare and the Welton Foundation.

Acknowledgment date: November 26, 2001.

First revision date: March 20, 2002.

Second revision date: August 19, 2002.

Acceptance date: January 24, 2003.

The submitted manuscript does not contain information about medical devices or drugs.

Foundation funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this article.

Address correspondence and reprint requests to Janet E Jeffrey, MSc, Department of Orthopaedic Surgery, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen, AB25 2ZD, UK; E-mail:

© 2003 Lippincott Williams & Wilkins, Inc.