This Classic Article is a reprint of the original work by M. N. Smith-Petersen, Treatment of Malum Coxae Senilis, Old Slipped Upper Femoral Epiphysis, Intrapelvic Protrusion of the Acetabulum, and Coxa Plana by Means of Acetabuloplasty. An accompanying biographical sketch of M. N. Smith-Petersen, MD, is available at DOI 10.1007/ s11999-008-0671-z. This article is 1936 by the Journal of Bone and...