He has unsparingly given his advice and positive criticism at all stages of this work and I am very happy to have this opportunity to express my deep gratitude for his encouragement. My sincere thanks are also due to Associate Professor E. V. S. Koskinen, M.D., for much valuable advice and for the interest he has shown in my work. Furthermore, 1. am indebted to Docents K. Solonen, M.D., and H. Julkunen, M.D., who kindly gave me valuable advice. The mathematical treatment of the results and their graphical representation, including part of the tabular arrangement, is the work of Mr. U. Attila, M.Sc., who also translated the manuscript into English. Many thanks are due to him for this help, as well as to Mr. K. Hart, M.A., who revised the English manuscript. My thanks are also due to the Librarian of the Clinic for Orthopaedics and Traumatology, Mr. Y. Siimes, who aided me in finding relevant references.