Vertebral coplanar alignment: a standardized technique for three dimensional correction in scoliosis surgery: technical description and preliminary results in Lenke type 1 curves.

STUDY DESIGN

Prospective multicentric study.

OBJECTIVE

To present the preliminary results of an innovative method for standardized correction of scoliosis, vertebral coplanar alignment (VCA), based on a novel concept: the relocation of vertebral axis in a single plane.

SUMMARY OF BACKGROUND DATA

Normal standing spine has no rotation in coronal or transverse planes, therefore X and Z axis of vertebrae are in the same plane: they are coplanar. VCA intends to relocate these axis in one plane, correcting rotation and translation, while X axis are returned to its normal posterior divergence in sagittal plane in thoracic spine.

METHODS

Twenty-five consecutive adolescent idiopathic scoliosis patients (Lenke type 1) underwent posterior surgery with segmental pedicle screw fixation. Slotted tubes were attached to convex side screws. Two longitudinal rods were inserted through the end of tubes. Then, they were separated along the slots, driving the tubes into one plane, making the axis of the vertebrae coplanar and thus correcting transverse rotation and coronal translation. To obtain kyphosis, distal ends of the tubes were spread in thoracic spine. Correction was maintained by locking a definitive rod in the concave side, then tubes were retrieved and the convex side rod, inserted and tightened. Correction was assessed on preoperative and postoperative full-spine standing radiograph. Vertebral rotation was measured on computed tomography-scan and magnetic resonance imaging.

RESULTS

Preoperative average thoracic curves of 61 degrees were corrected to 16 degrees (73%). Preoperative average thoracolumbar curves of 39 degrees were corrected to 12 degrees (70%). Preoperative average thoracic apical rotation of 24 degrees was corrected to 11 degrees (56%). Preoperative average thoracic kyphosis of 18 degrees remained unchanged after surgery; however, no patients had kyphosis <10 degrees after surgery. Rib hump improved from 30 to 11 mm (65%). There were no perioperative complications.

CONCLUSION

VCA provided excellent correction of coronal and transverse planes with normalization of thoracic kyphosis in Lenke type 1 adolescent idiopathic scoliosis surgery.