Analysis of shoulder complex function after posterior spinal fusion in adolescents with idiopathic scoliosis

Background: Nonsurgically treated patients with AIS demonstrate altered scapular kinematics and decreased patient-reported shoulder function compared with typically developing adolescents. It is unknown whether surgical correction of the spine deformity has beneficial or detrimental effects on scapulothoracic joint function, as previous assessments of shoulder function following surgery have only focused on humerothoracic motion. The objective of this study was to perform a comprehensive analysis of scapular kinematics before and after PSF and compare postoperative scapular kinematics in AIS to those of a typically developing cohort. Methods: Typically developing adolescents (n=33) and patients with AIS (n=20) with a planned PSF surgery were recruited. Motion capture was used to analyze scapular kinematics at rest and in full abduction. AIS subjects were evaluated before surgery and at a 6-month follow-up. Individual changes following surgery were assessed, and postoperative scapular kinematics were compared with the typically developing subjects. Results: Patients with AIS patients in this study demonstrated significant losses of scapulothoracic range of motion for the convex side shoulder and gains of scapulothoracic range of motion for the concave side shoulder following PSF. When compared with typically developing adolescents, the resting scapular position of the postoperative AIS group seemed normalized, but the AIS group still exhibited altered scapular motion, particularly along the upward rotation and tilt axes. Conclusions: Patients with AIS demonstrated significant changes at the scapulothoracic joint following PSF. Compared with typically developing adolescents, scapular resting position normalized, but the AIS group still demonstrated altered scapular kinematics, including patterns associated with shoulder pathology. The results of this study will inform the course of short-term postoperative rehabilitation by addressing the upper extremity implications of PSF for individuals with AIS. Level of Evidence: Level III.