Anteroposterior knee radiographs of six individuals with the R718W mutation at different ages (as indicated in the figure). (A) The epiphyses are small but regular, there is mild metaphyseal wedging. (B) Wedging is more pronounced and the contour of the epiphyses is irregular. (C) Progress of ossification has resulted in accessory medial and lateral nuclei at the proximal tibia, with what looks like a cleft between the regular and the accessory nuclei (“crevice”). At the distal femoral epiphysis, ossification is more advanced, leaving lateral and medial epiphyseal “spurs”. (D) The proximal tibial epiphysis shows here a distinct ossific “ring” surrounding the normal central nucleus. This image corresponds to the magnetic resonance images in fig 4. (E) Epiphyseal ossification is complete. Apart from small dimensions and edginess of the distal femoral epiphysis, the previous changes are no longer discernible. (F) In the adult, the epiphyses are small but otherwise undiagnostic. m, months; y, years.