Minor change in the sulcus angle during the first six years of life: a prospective study of the femoral trochlea development in dysplastic and normal knees.

PURPOSE

The aetiology of femoral trochlear dysplasia is unknown. The aim of this prospective cohort study was to describe trochlear development in a newborn population during the first six years of life.

METHODS

In an earlier study, the femoral trochlea was examined by ultrasound in 174 newborns. A dysplastic trochlea was defined with a sulcus angle (SA) above 159°. Two groups were defined, one group of 15 knees with SA > 159° (dysplastic group), and one group of 101 knees with SA < 159° (non-dysplastic group). In the present follow-up study, the children were further examined at six, 18 and 72 months.

RESULTS

There was a statistically significant difference in the SA between the dysplastic and the non-dysplastic group at all follow-ups (p < 0.001). A small but statistically significant change in the SA between 0 to 72 months was detected for the dysplastic knees (p = 0.032) and for the controls (p < 0.001).

CONCLUSION

Only minor changes in the anatomy of the femoral trochlea from newborn to age six years were found. A dysplastic trochlea at birth remains shallow and the anatomy does not change from normal to dysplastic during the same time span.

LEVEL OF EVIDENCE

II.