Lumbar facet and interfacet shape variation during growth in children from the general population: a three-year follow-up MRI study.

STUDY

DESIGN

A descriptive magnetic resonance imaging (MRI) study on the growth of the lumbar zygapophyseal facets and interfacet area in children from the general population.

OBJECTIVE

To characterize lumbar facet and interfacet shape variation during growth.

SUMMARY OF BACKGROUND DATA: The growth of the lumbar facet and interfacet area in children from the general population has rarely been discussed in the literature. This is an important caveat considering the important role these structures play in the development of spinal anomalies.

MATERIALS AND

METHODS

All lumbar (L1-S1) facet and interfacet widths and transverse orientations were measured twice by the same investigator (Y.M.) from T2-weighted MRIs of 100 healthy children (51 boys and 49 girls) from the general population at the mean age of 12 to 13 years (t0) and after 3 years at the mean age of 15 to 16 years (t1) using the iQ-VIEW system. Statistical analysis included Student t tests and Pearson r after the Kolmogorov-Smirnov test for normal distribution. RESULTS.: The superior facet width is correlated with individual's height only in boys at t0 (0.56 < or = r < or = 0.66). No significant asymmetry in lumbar facet width and orientation is seen in children independent of gender both at t0 and t1. Lumbar facets have widened significantly only in boys from t0 to t1 (up to 30.8%). Girls at t1 manifest greater superior interfacet width relatively to the superior vertebral body width than boys at L2-L4. No significant difference is indicated in facet orientation of the 2 sexes at t0 and t1. In boys only, the superior facet rotates significantly from t0 to t1 (up to-10 degrees in the interfacet angle) toward a more sagittal orientation.

CONCLUSION

The lumbar facet joints in boys continue to develop after the age of 12, whereas facets in girls seem to have reached maturity at that age. Moreover, lumbar facet asymmetry when noted in children can be considered as a deviation from the normal state. Further research should look into what the consequences might be.