Scoliosis Research Today is a free monthly online journal that collates and summarizes the latest research about Scoliosis, including details on treatment, exercises, surgery, symtpoms.

Facet asymmetry in normal vertebral growth: characterization and etiologic theory of scoliosis.

Masharawi YM, Peleg S, Albert HB, Dar G, Steingberg N, Medlej B, Abbas J, Salame K, Mirovski Y, Peled N, Hershkovitz I

Spinal Research Laboratory, Department of Physical Therapy, The Stanley Steyer School of Health Professions, Sackler Faculty of Medicine, Tel-Aviv University, Ramat Aviv, Israel. yossefm@post.tau.ac.il

STUDY DESIGN: The shape and orientation of the thoracic and lumbar zygapophyseal facets at the T1-L5 level in children were measured and analyzed. OBJECTIVE: To detect the pattern of zygapophyseal facet asymmetry in the thoracic and lumbar spines in children. SUMMARY OF BACKGROUND DATA: Whereas many studies have defined the pattern of zygapophyseal facet asymmetry in adults, there is insufficient data in children. METHODS: A 3-dimensional digitizer was used to measure zygapophyseal facet size, topography (length, width, concavity, convexity, and lateral interfacet height), and orientation (transverse and sagittal facet angles) at the T1-L5 level. Thirty-two complete, nonpathologic skeletons of children (age range from 4 to 17 years), housed at the Hamman-Todd Human Osteological Collection (Cleveland Museum of Natural History, Cleveland, OH) were assessed. Statistical analysis included paired t tests and analysis of variance. RESULTS: In general, zygapophyseal facet asymmetry in children exists only in the superior facets of the thoracic spine and is independent of age: The right superior facet is significantly shorter than the left in all thoracic vertebrae T1-T12 (up to -2.91 mm at T1), and significantly wider than the left in thoracic vertebrae T1-T9 (T8 excluded) (P < 0.003). The right superior transverse and sagittal facet angles are significantly greater than the left in thoracic vertebrae T1-T11, indicating a lesser inclination (in the sagittal plane) and more frontally positioned facet (in the transverse plane) (P < 0.003). Facet asymmetry was not evident in the superior or inferior facets of the lumbar vertebrae. CONCLUSION: Facet asymmetry in thoracic vertebrae appears in early childhood. The pattern of this asymmetry differs from that reported for adults and may be considered as a possible contributing etiological factor in the development of different types of idiopathic scoliosis.

Published 11 April 2008 in Spine, 33(8): 898-902.
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