Dislocation and/or congenital malformation of the shoulder joint. Observations on a Mediaeval skeleton from Denmark

The purpose of this paper is to present a Mediaeval skeleton of an approximately 16 year old boy, which was excavated at a Danish cemetery containing ca. 150 graves. The skeleton reveals several pathologic changes, probably due to congenital malformation. The most intriguing find is seen at both scapulae, and the changes are bilateral symmetric. Both the glenoid cavities are placed posterior but at the normal height of the bone. The joints are almost perpendicular to their normal direction. The size of the glenoid cavities is normal and the shape is rather flat in accordance to the development stage of the skeleton, where the epiphysis of the rim has not yet appeared to form the gently concave fossa as normally seen in adults. Both the surface and the borderlines of the glenoid cavities are, however, more irregular than normally at that age. The position of the joints may be caused by dislocation and/or congenital malformation which is discussed. Due to the shape of the cavities, to the symmetric bilaterality, and to the minor congenital malformations, it is primarily believed to be caused by congenital malformation. Probably the young man was not much affected by the malformation of the shoulder joints, which is indicated by the normal form and size of the humeri and the well-developed muscle attachments of the bones. The claviculae seem shorter and more twisted than normal, which may be caused by a twisting of the scapulae. So the glenoid cavities may have pointed almost in the normal direction in spite of the malformation. Other minor malformations are spina bifida of the atlas and the 5. lumbar vertebra, multiple minor changes of the joints of both feet and malformations of one metatarsal bone in both feet. Agenesi of the praemolars is also seen. Although our study of the literature, we have not succeeded in correlation our finds with any known congenital syndrome, and as far as we know no similar case has been described in clinical observation or in skeletal finds.