ON THE INCIDENCE OF THE SUPRACONDYLOID PROCESS IRENE PIEPER Washington University, Department of Anatomy Testut’ found as the result of his investigation on the supracondyloid process in a series of 929 bodies in the dissecting room a t Lyon that the incidence was 1 per cent. The examination by Terry2 of 683 white patients in a free dispensary, a group of individuals whose intelligence and social status are comparable with Testut’s group, gave an incidence for the spur of 0.87 per cent. HrdliEka’s3figures from over 3000 bones of adult whites, males and females, give the average incidence 1 per cent (0.999) for the process form over 3 mm. in height. This material including the Huntington collection was in large part derived from the dissecting room. Following the paper of Testut, appeared a work by Nicolas4 (’90) on cadavers of the insane showing a high percentage (5.2) of the process; and in 1899 the study of Ugolotti5 resulted in an incidence of 11.29 in arm bones of criminals and insane. More recently Zagni6(’23) reported an investigation of the variation in criminals with an incidence of 3.5 per cent for the process form; the skeletons of 350 individuals were examined. The question has arisen in consequence of the high incidence in criminals and mental defectives shown in these papers, of a possible correlation between the mental status and the variation under consideration. Recently Cady7 (’21) investigated 1000 insane patients of the St. Louis Sanitarium. These subjects presented many kinds of mental disorders, a group constituted for testing further this question. Cady’s method of examination, previously employed by Terry (’20), was that of palpation of the humerus in the living. The in. cidence obtained by him was 1.2 per cent. The present investigation, undertaken a t Professor Terry’s suggestion, has for its object the determination of the incidence of the supracondy- . ’Testut, (L.)-L’Apophyse sus-epitrochl6ennechez l’homme. Internat. Monatachr Anat. b Physiol., 1889, VI. ZTerry, (R. J.)-A study of the supracondyloid process in the living. A m . J Phvs. Anthrob.. 1921. IV. jHrdliEka, id.)-Incidence of the supracondyloid process in whites and other races. Am. J . Phys. Anthrop., 1923, VI, 405. 4Nicolas,(A.)-Nouvelles observations d’apophysesus-epitrochl6ennechez l’homme Rev.Biol. du Nard.. 1890. 111. 5Ugolotti, (F.)-Sul apofisi sopraepitrocleare dell’ omero nei normali e nei delinquenti. Arch. psich. Sc. pen. b Antrop. crim., 1899, XX, m 2 4 8 . %agni, (L.)-La spina sopraepitrocleare nei criminali. Instituto di Anatomia Umana Normale dell R. Universita’ di Modena, 1923. Tady, (L. D.)-The Incidence of the Supracondyloid Process in the Insane. Am. J . Phys. Anthrop., 1922, IV. 169 AM. J. PHYS.ANTHROP.,1925, Vol. VIII, No. 2 170 IRENE PIEPER loid process in physically sound and intelligent people, able to maintain themselves by their own ability and exertions. Material was obtained in the several departments of Washington University, members of the departmentai staffs and the students participating in the investigation by undergoing the examination of the arm. This was conducted in accordance with the method of palpation used by Terry, the discovery of the spur being confirmed by the X-ray. Members of several clubs, clerks, and some private patients (suffering acute diseases) of several physicians were also examined. The following table summarizes the material studied. TABLE I. Males 21 years and over. .......................... Under 21 years.. ............................ 309 34 Females 411 36 Total 720 70 790 DESCRIPTION O F CASES Observation I. Male. French English extraction. Unmarried; 21 years old. Supracondyloid process right. Form hooked. Position antero-medial. Distance above trochlea 25 nim. Height 7 mm. Strength of pronation r) 1. Supratrochlear foramen. Family living: both parents, one brother, maternal grandmother and several uncles. No processes found among them. Occupation, medical student. Observation 11. Male. American. Scotch English extraction. Unmarried; 23 years old. Supracondyloid process left. Form curved. Position medial. Distance above trochlea 74 mm. Height 7.+ mm. Strength of pronation r( 1. Family living: both parents, three brothers and one sister. No processes found. Three sisters dead. Occupation, medical student. Observation 111. Male. American. German extraction. Unmarried; 25 years old. Supracondyloid process left. Form hooked. Position medial. Distance above trochlea 68 mm. Height 6.5 mm. Suprahrochlear foramen. Strength of pronation r ) 1. Family living : both parents, one sister and several uncles. No processes discovered. Occupation, medical student. Observation IV. Male. Italian. Unmarried; 21 years old. Supracondyloid process right. Form hooked. Position medial. Distance above trochles 65 mm. Height 11 mm. Occupation laborer. No other data have been available up to time of writing. Of the 790 people examined 4 presented processes: an incidence of 0.50 per cent. If adults alone are considered (720) the figure of those having the variation rises to 0.55 per cent. It has been pointed out by both Terry and Cady that since the variation has been found in children, the newborn and in the foetus, grotips including children may with THE SUPRACONDYLOID PROCESS 171 propriety be used for calculating incidence. Testut’s group included some subjects under 21 years since two cases (one of 11 and one of 13 years) were described as having the variation. If the results are compared after including children we find the incidence for the dissecting room and dispensary groups of Testut and Terry to be 1 per cent and 0.86 per cent respectively; for the physically sound and intelligent group 0.50 per cent, a considerably lower figure. Comparing only adults, the incidence stands: dispensary group 1.16 per cent; insane group 1.2 per cent; Hrdlizka’s group, chiefly from the dissecting room, 1.0 per cent; sound and intelligent group 0.55 per cent. Our investigation was confined to adults as much as possible in order that the evidence bearing on the subject’s ability to maintain himself and upon his degree of intelligence would not come into question. Very few laborers were included in the test and these only because they were persons of known exceptional ability. Search among the living relations of the subjects for evidences of hereditary tendency has so far revealed nothing in the present study.