1 Centre for Deformity Correction and Joint Preserving Surgery, Kliniek ViaSana, Hoogveldseweg 1, 5451 AA, Mill, The Netherlands. vanheerwaarden@yahoo.com.
2 Department of Orthopaedic Surgery and Traumatology, Kantonsspital Baselland (Bruderholz Liestal, Laufen), 4101, Bruderholz, Switzerland.