Karl Nissen, born in Otago in 1906, had a Danish father and an English mother. He was educated in New Zealand and entered the medical school in Otago, where he qualified in 1932. He first went into general practice before deciding to specialise. He undertook research into several generations of a family affected by brachydactyly, and a thesis on this gained him the MD (New Zealand) in 1934. In the next year he came to England to train in surgery. He was appointed as the first resident surgical officer at the newly established Princess Elizabeth Orthopaedic Hospital in Exeter, where he worked under Norman Capener. From 1943 to 1945 he served as an orthopaedic specialist in the RNVR in South Africa. He was therefore on hand when the epidemic of poliomyelitis broke out on the island of St Helena and the island's inhabitants were fortunate in having his presence and advice in dealing with this disaster. In 1946 he was appointed consultant orthopaedic surgeon to the Royal National Orthopaedic Hospital, Stanmore, where he stayed until his retirement in 1971. He was one of the first to operate for carpal tunnel syndrome and Morton's neuroma and will be particularly remembered for his management of primary osteoarthrosis of the hip by osteotomy before the later hip replacement surgery was introduced and perfected. He wrote a paper which drew him to the attention of Sir Reginald Watson-Jones in 1948 and he went on to give distinguished service as an assistant editor of the *Journal of bone and joint surgery*. When he first came to England he had enjoyed some of the courses run by the Fellowship of Postgraduate Medicine and later for some twenty years ran a popular course for the Fellowship, many of his trainees, especially from overseas, becoming his close friends. He continued to take an interest in the Fellowship, serving on its Council and finally as its President from 1968 to 1976. After retirement he maintained an active interest in orthopaedic surgery, and his enquiring mind led him deeply into study of the genetic basis of osteoarthritis. A few months before his death he attended a meeting of the British Orthopaedic Association, where he was given a standing ovation after receiving its honorary Fellowship. He had enjoyed a happy marriage with his wife Honor, who in later years sadly suffered from multiple sclerosis. Karl was devoted to her, and often took her for holidays abroad in her wheelchair. Their happy life together was ended by her death in 1981. Karl died in his sleep on 30 December 1995, survived by a daughter, a son and three grandchildren.