Radiology, Vol 177, 197-200, Copyright © 1990 by Radiological Society of North America
Usefulness of a short femur in the in utero detection of skeletal dysplasias
AB Kurtz, L Needleman, RJ Wapner, P Hilpert, K Kuhlman, PN Burns, RI Feld, DG Mitchell, S Segal and L Blum
Department of Radiology, Jefferson Medical College and Thomas Jefferson University Hospital, Philadelphia, PA 19107.
In 28 fetuses studied during a 4 1/2-year period, the initial femur was
below 2 standard deviations (SDs) of the mean when compared with the
biparietal diameter. These fetuses were considered at risk for skeletal
dysplasias and were followed up. Studies were performed at a mean
gestational age of 26.7 weeks (range, 15.3-41.0 weeks). Group 1 had a femur
length 1-4 mm below the 2-SDs line (range, -2.0 to -4.0 SDs); no other
abnormalities were detected. Interval examination of 12 femurs showed that
10 either remained shortened to the same degree or had a growth spurt. At
birth, all subjects were healthy except one with mild growth retardation
and one with a chromosomal abnormality. Of the two subjects that failed to
continue normal growth, one was healthy and the other was a heterozygous
achondroplastic dwarf. Group 2 had greater femoral shortness; all
measurements were more than 5 mm below the 2-SD line (range, -4.3 to -31.0
SDs). All had fetal abnormalities and significant skeletal dysplasias. The
authors conclude that the number of millimeters below the 2-SDs line is an
accurate, easy criterion for evaluation of femoral length.
