ASSESSMENT OF ROTATION IN PROXIMAL HUMERAL OSTEOTOMY

The correlation between the shift measured on bone surface in rotatory osteotomy and the radiologic change of the retroversion angle was ana lyzed. The humeral head retroversion was measured radiographically in 7 isolated humeri by means of a semiaxial projection. All bones were t hen osteotomized and the humeral head rotated in order to increase and decrease the retroversion. The retroversion was measured radiographic ally for each new relational position of the head. The relationship be tween the measured shift in rotatory osteotomy and the change of retro version was found to be linear. Twelve patients with recurrent anterio r shoulder joint dislocations and a small humeral head retroversion we re operated on in order to increase the retroversion. In all patients the increase of retroversion angle was smaller (57%) than expected on the basis of the shift in osteotomy and humeral diameter. The mean inc rease of retroversion was 2 degrees/mm shift (range 1.3-3.0 degrees/mm ).