We appreciate your careful reading of our study and are thankful for your questions. Here are our responses.

• 1.

  This part was added during the revision process, and unfortunately a typing error has been overlooked. The total of 28 is correct, but there should have been 6 male and 22 female subjects.

• 2.

  Yes, at the University of Zurich, hand-wrist radiographs are taken routinely for diagnostic and educational purposes in teenagers.

• 3.

  This x-ray device was set up more than 30 years ago, and the distance has been left unchanged for longitudinal purposes. The main reason for having a longer distance from the x-ray source to the midsagittal plane was to have less magnification.