Autotraction stress roentgenography for demonstration anterior and inferior instability of the shoulder joint.

A form of stress roentgenography is presented for the diagnosis of anterior and inferior shoulder instabilities. Stress is induced by anterioinferior traction concentrated on the shoulder during extension of the flexed hip, when patients hold their legs on the side being examined, with both hands. The anterior and inferior shifts of the humeral head in relation to the glenoid fossa then are measured from anteroposterior and modified axillary roentgenograms. This method was employed in 16 shoulders with recurrent anterior dislocation, 11 recurrent anterior subluxations, nine multidirectional instabilities, and 19 control shoulders. Mean anterior translations were 3 mm and 5 mm, and inferior translations were 7 mm and 10 mm for the control and recurrent dislocation groups, respectively. There were statistically no significant differences between those groups. In the recurrent anterior subluxations, the corresponding translations were of a completely different order, 21 mm and 19 mm, respectively, allowing the distinction from the controls and recurrent anterior dislocations in most cases. The shifts found in multidirectional instabilities, averaging 27 mm and 26 mm, respectively, were significantly greater than for the recurrent subluxations, but the differences were not great enough for accurate differential diagnosis in individual cases. Autotraction stress roentgenography of the shoulder may be of use in the diagnosis of recurrent anterior subluxations and anteroinferior multidirectional instabilities. It also gives good general views of the looseness of the glenohumeral joint.