Kinematic Effects of Derotational Osteotomy of the Humerus in Patients with Internal Shoulder Contracture Secondary to Erb's Palsy-A Retrospective Cohort Study.

Background: Internal rotation contractures of the shoulder are common sequelae of conservatively treated obstetric brachial plexus palsy (OBPP) with incomplete spontaneous neurological recovery. Humerus derotation osteotomy has been suggested as a possible treatment option to improve arm positioning. However, consensus as to whether humerus derotation osteotomy can successfully restore limb function is missing. Methods: In the present controlled cohort study, we aimed at analyzing global upper extremity kinematics with a 3D-video analysis system in children with shoulder internal rotation contractures secondary to OBPP before, and one year after, humerus derotation osteotomy. Patients under 18 years of age that presented to our center with conservatively treated internal rotation contractures of the shoulder and subsequently underwent humerus derotation osteotomy were included. The unimpaired arm served as a respective control. Results: Pre-operatively, all patients showed severe internal rotation contractures of the shoulder of almost 60° at rest. At the follow-up, the position of the shoulder at rest was greatly shifted to 9° of internal rotation. The patients showed statistically significant improvement in maximum external rotation and abduction of the shoulder, as well as in maximum flexion of the elbow, and the range of motion of pro/supination. The maximum internal rotation of the shoulder, however, was diminished after the osteotomy. Conclusions: Our data indicated that derotational osteotomy is a promising procedure which can be used to correct for internal rotation contractures secondary to OBPP. Moreover, 3D-video analysis proved to be a useful tool that supplies the surgeon with both precise information about the degree of distortion pre-operatively, thus helping to decide on the amount of correction, and secondly, a measurement of the post-operative gain in upper extremity function.