Introduction: Pedicle screw fixation of the main thoracic curve in individuals with AIS provides improved curve correction in comparison to hooks and hybrid systems. However, the use of pedicle screws can be costly, carry a risk of neural injury, and potentially increase health-care costs.
Objectives: To present the prospective radiographic comparison of 3 pedicle screw strategies and their costs analyses in the treatment of thoracic AIS.
Materials & Methods: Ninety-four AIS patients underwent surgery (range: 6–13 levels). Seventeen patients underwent the key-vertebral screw strategy (KVSS), noted as bilateral screw fixation at the levels above and below the fusion construct as well as 1 screw at the apex with 1 screw each at its adjacent levels. Forty-two patients underwent alternate level screw strategy (ALSS), which entailed bilateral screw fixation at alternate levels. Thirty-five patients received contiguous multilevel screw strategy (CMSS), characterized as bilateral screw fixation at every level. Titanium rods were utilized in the KVSS and ALSS cases, whereas stainless steel rods were applied in patients with CMSS. Pre- and immediate postoperative postero-anterior and fulcrum bending radiographic Cobb angles were obtained of all patients. The fulcrum flexibility and the fulcrum bending correction index (FBCI) were assessed.
Results: The FBCIs of the KVSS, ALSS, and the CMSS were 119%, 122%, and 152%, respectively. In comparison to the CMSS, the KVSS and ALSS were associated with pedicle screw cost reductions of 41.7–73.1% and 33.3–46.2%, respectively.
Conclusion: Although the CMSS may provide an increased amount of FBCI, the KVSS and ALSS are safe, cost-effective, and achieve an FBCI greater than 100 % in the majority of cases. In AIS patients with flexible thoracic curves, the KVSS and ALSS are viable alternatives to CMSS. In addition, one should remain cognizant that variation in instrumentation (e.g. stainless steel rods vs. titanium rods) and potentially improper radiographic methods to assess the flexibility of the curve may affect the degree of FBCI.