Abstract
The term “skeletal skew” recognises the oblique positioning or slanting of two similar halves of the body. It is preferred to asymmetry which describes a disproportion between two quantities with no common measure. In 1982 69 babies with skeletal skew were described in relation to the abduction contracture which affects the hip and leg on which the body lies in persistent sidelying. The skeletal skew was evident at birth in 24 cases, but only became obvious at 4–6 months of age in the remaining 45 cases.
The adducted, uppermost hip looks spuriously dysplastic but the proximal femoral ossification centre is usually equal to the opposite side and the ultrasound scan is within normal limits. Associated skewing affects the skull (plagiocephaly) the neck (torticollis), thorax, pelvis and feet in a proportion of these squint babies. When the pelvic radiograph is assessed confusion is avoided if the ischial lower border is set horizontally; this corrects the apparent, increased acetabular inclination (angle) on the adducted side. The concomitant rotational artefact can be appreciated by reviewing differences in the widths of the iliac wings and obturator foramina, sacral-symphysial alignment and femoropelvic overlap.
Of the 45 cases with pronounced skeletal skew manifesting at 3–4 months of age, the oblique positioning corrected during early walking age, as shown by calculating the difference between the abduction arcs of the two hips. The plagiocephaly, with flattening of the brow on the upper side, may persist until skeletal maturity.
Follow up at 18 years was achieved in 41 of the 45 cases. There was one case of mild bilateral hip dysplasia and one case of a leg length discrepancy of 1.5 cm. In 40 cases the hips were normal clinically and radiographically although 5 had persistence of increased femoral anteversion. No splintage or stretching of the adducted hip had been undertaken during infancy and hence the great majority of cases with skeletal skew correct. Ultrasound assessment is advised in borderline cases for this relatively common condition which results in a referral rate of 5.3 per 1000 live births, compared to the Edinburgh neonatal splintage rate for hip instability of 3.8 per 1000 live births.
The abstracts were prepared by Mr N. M. P. Clarke. Correspondence should be addressed to him at the British Orthopaedic Association, Royal College of Surgeons, 35-43 Lincoln’s Inn Fields, London WC2A 3PN.
