Hybrid Constructs for Tridimensional Correction of the Thoracic Spine in Adolescent Idiopathic Scoliosis A Comparative Analysis of Universal Clamps Versus Hooks

Study Design. Retrospective study of prospectively collected data. Objective. Compare Universal Clamps (UCs) and hooks for the thoracic correction of adolescent idiopathic scoliosis (AIS). Summary of Background Data. In scoliosis surgery, sagittal correction is as important as frontal correction due to the risk of junctional kyphosis. Compared to all-screw constructs, hybrid constructs with lumbar pedicle screws and thoracic hooks or sublaminar wires have been shown to achieve similar coronal correction while providing superior postoperative thoracic kyphosis. The authors used a novel sublaminar thoracic implant, the UC with improvements over sublaminar wires. Hybrid constructs using thoracic UCs were compared to those with thoracic hooks. Methods. This series involved 150 patients treated for AIS with hybrid constructs. A total of 75 consecutive patients operated from 2001 to 2003, who had thoracic hooks with in situ contouring, distraction, and compression ( Group 1), were compared to 75 consecutive patients operated from 2004 to 2006, who had thoracic UCs with posteromedial translation ( Group 2). All had intraoperative somatosensory/motor-evoked potential monitoring and at least 2-years follow-up. Results. Except for follow-up ( longer in Group 1), the 2 groups were similar before surgery. The UCs achieved better thoracic coronal correction (P < 0.001), Cincinnati index (P < 0.001), kyphosis (P < 0.02), and apical rotation (P < 0.001). In normokyphotic or hypokyphotic patients, the UC corrected thoracic kyphosis by 11.2 (55%) versus 0.4 (2%) achieved by hooks (P < 0.0001). These differences were stable at last follow-up. There were no intraoperative complications or changes in somatosensory/motor-evoked potentials. UC reduced operative time by 20% ( 60 minutes; P < 0.001) and blood loss by 23% (250 mL; P < 0.001). Conclusion. Although both of these hybrid constructs efficaciously corrected the coronal and axial deformities in AIS, the results of the UC technique were superior to those achieved with hooks in all 3 planes, especially the sagittal plane. Moreover, the UC technique is straightforward and safe, reducing both operative duration and blood loss.