Axial Plane Deformity of the Shoulder in Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Prospective observational study.

OBJECTIVE: To study axial plane deformation of the shoulder in adolescent idiopathic scoliosis (AIS) and try to correlate it with curve type and surgical correction.

SUMMARY OF BACKGROUND DATA: It is established that AIS is a 3-dimensional deformity. The rib hump is the most common manifestation of axial plane deformations; the least common manifestation seems to be upper trunk and shoulder rotation, which has been hitherto undescribed.

METHODS: Fourteen consecutive, operated cases of AIS were analyzed prospectively. Preoperative and postoperative x-rays of the spine and clinical photographs were studied. Clinical photographs (top view) were taken with patients in the sitting position, to show shoulder level in relation to the axis of the head and pelvis. Chest computed tomography scans were also studied to determine the direction of apical vertebra and trunk torsion.

RESULTS: All 14 patients in this series had their right shoulders anteriorly rotated preoperatively (anticlockwise). The direction of rotation seemed unrelated to the curve type and shoulder elevation, although most had rib humps on the right. This shoulder rotation was corrected postoperatively by routine maneuvers done for scoliosis correction. Minor residual rotation was seen in 6 patients who also had minimal persisting rib hump. In 1 case the axial plane rotation worsened, although the shoulder level and trunk symmetry improved significantly. The apical vertebral rotation on computed tomography had little bearing on the direction of shoulder rotation.

CONCLUSIONS: Axial plane rotation of the shoulder is a hitherto un-described dimension of AIS deformity complex. Much of it corrects spontaneously with correction of the thoracic spinal deformity.