All-pedicle screw versus hybrid instrumentation in adolescent idiopathic scoliosis surgery: a comparative radiographical study with a minimum 2-Year follow-up.

Study Design: Comparative analysis of 2 groups of patients who underwent surgical treatment of adolescent idiopathic scoliosis (AIS).
Objective: To compare a segmental pedicle screw only system with a hybrid system for the treatment of Lenke type 1 AIS curves.
Summary of Background Data: Although previous AIS studies have tried to compare various constructs with the all-pedicle screw fixation, all have failed to address important confounding variables, such as skeletal maturity, preoperative flexibility of the curve, and factors associated with a multicenter or multisurgeon analysis.
Methods: The medical records and spinal radiographs of patients with AIS treated surgically by a single surgeon between 2000 and 2009 were retrospectively reviewed. Patients with Lenke type 1 curves and minimum follow-up of 2 years were divided into 2 groups that were meticulously matched: group 1 consisted of patients in whom the all-pedicle screw construct was used, whereas group 2 included patients who were treated with the hybrid hook-screw system.
Results: Group 1 included 34 patients and group 2 included 29 patients. At the last follow-up, thoracic curve correction averaged 70.4% for the all-pedicle screw group and 60% for the hybrid group (P = 0.19). The all-pedicle screw group showed a significantly greater increase in thoracic kyphosis than the hybrid group system (P = 0.04). Global sagittal balance showed greater improvement in the all-pedicle screw group during the immediate postoperative that was lost by the last follow-up. The all-pedicle screw system revealed less intraoperative blood loss but greater operating time than the hybrid construct. After controlling for length of follow-up, no statistical difference in any of the radiographical parameters measured was recorded.
Conclusion: With the exception of global sagittal balance, the pedicle screw system provided better maintenance of its corrective parameters when followed for greater than two years.
Level of Evidence: 3.