Mechanism of shoulder movements and a plea for the recognition of "zero position" of glenohumeral joint.

Amulya Kumar Saha, whose early work on the “zero position” of the shoulder joint is reprinted in this symposium, was born in 1913 in Pabna in undivided India (now in Bangladesh). After graduating with degrees in both science and medicine from Calcutta University, where he received his surgical training under Professor L. M. Banerjee, one of the outstanding surgeons of India in his time, he volunteered in the British Indian Army during World War 11. He saw service in Burma and in the Middle East, where he became a surgical specialist and quickly rose to the rank of Major. After demobilization, he travelled to the United Kingdom for additional training and study in surgery. He received the titles of F.R. C.S (Eng.), F.R. C.S. (Edin.), and M.Ch.Orth. (L‘Pool) in 1948. He became interested in the shoulder mechanism while assisting Professor S. K. Basu at the Indian Museum in 1940. He delivered his first dissertation to the Liverpool orthopedic group in 1948. Thereafter, the shoulder was one of his abiding interests. On his return to India, Saha was first appointed to the post of Reader in Surgery in Gwalior Medical College. Subsequently, he joined the Nilratan Sircar Medical College and the University of Calcutta as Associate Professor of Surgery, where he served from 1949 to 1955. From 1955 to 1963, he served as Professor Director in the Department of Surgery at the same institution and eventually became an Honorary Consultant orthopedic surgeon, a position he held from 1964 to 1972. In 1972 he was made Emeritus Professor of Orthopaedic Surgery. During Professor Saha’s time, orthopedic surgery was just becoming recognized as a specialty in India. Through the force of circumstances, he was appointed to a post in general surgery, although he was primarily interested in orthopedics. In fact, he was largely instrumental in popularizing orthopedics in Calcutta and training a number of younger surgeons in this field. They have maintained his high standards at Nilratan Sircar Medical College Hospital in Calcutta. Professor Saha’s major contribution to orthopedic research and clinical orthopedic practice is in relation to the shoulder joint. While at Nilratan Sircar Medical College, he conducted extensive studies on the functional anatomy of the shoulder joint from anatomic, anthropologic, morphologic, radiologic, and electromyographic, as well as mathematic, points of views. As a result of these studies, he published his work on the zero position of the glenohumeral joint in 1950. In 1957 he was invited by the Royal College of Surgeons of England to deliver a Hunterian Lecture, “Zero-position of the Glenohumeral Joint: Its Recognition and Clinical Importance. ” At about this time (1954), he became interested in the study of recurrent dislocation of the shoulder joint and in rehabilitating patients with paralysis of the shoulder following poliomyelitis. He was convinced that dynamic stability was essential during various stages of elevation of the shoulder joint with versatile ranges of movements. He postulated that there are three main factors that maintain the dynamic stability of the fully developed shoulder joint: ( 1 ) normal retrotilt of glenoid articular surface in relation to the axis of the scapula; (2) the optimum retrotorsion of the humeral head in relation to the shaft; (3) balanced power of the horizontal steerers. Based on these principles, he evolved his operations for treatment of recurrent dislocation of the shoulder joint, which he considered to be primarily due to lack of dynamic stability during abduction. In some cases of recurrent anterior dislocation of the shoulder joint, there was no history of injury, and in many cases no Bankart lesion was demonstrable. He was of the opinion that the Bankart lesion possibly was not the cause of recurrent anterior