Maintenance of construct integrity with subaxial cervical pedicle screws when crossing the cervicothoracic junction in complex pediatric deformity: an international multicenter study.

Abstract

Objective: In cases of complex pediatric spinal deformity, posterior spinal instrumentation crossing the cervicothoracic junction (CTJ) may be required. This is most frequently encountered for revision surgery to address proximal junctional kyphosis (PJK). In the cervical spine, lateral mass screws are most commonly used, although they may result in biomechanically weak proximal constructs and predispose to instrumentation failure. The use of supplemental anterior constructs has recently been reported with promising results, but this necessitates an additional surgical procedure. Subaxial cervical pedicle screws can provide good biomechanical fixation without the need for an anterior approach, but outcome data have been very limited. The purpose of this study was to assess radiographic and clinical outcomes at two years in pediatric patients who have undergone posterior spinal instrumentation and fusion (PSIF) crossing the CTJ using subaxial cervical spine pedicle screws.

Methods: The Pediatric Spine Study Group (PSSG) registry was queried to identify patients ≤ 21 years old who underwent PSIF crossing the CTJ with two-year minimum clinical and radiographic follow-up. Patients were excluded if they had a history of anterior stabilization or if their fusion construct with subaxial pedicle screws started below C6. Clinical, surgical, and radiographic parameters were assessed, and measurements were compared statistically.

Results: Then, 8 patients (6 female and 2 male) met inclusion criteria, with a mean age at surgery of 11.2 ± 3.3 years. All patients underwent PSIF crossing the CTJ (mean levels fused 15.6 ± 6.6). The mean density of subaxial cervical pedicle screws was 61.9% ± 27.8 (range 28.5 to 100%). The major coronal curve averaged 54.7° ± 19.6 preoperatively and 34.5° ± 13.6 postoperatively (41.5% ± 26.5 correction; p = 0.03). The average major sagittal curve was 55.9° ± 20.6 preoperatively and 29.6° ± 9.6 (44.2% ± 18.0 correction; p = 0.01) postoperatively. There were no major intraoperative or postoperative complications. Deformity parameters remained stable without radiographic evidence of PJK in 8/8 patients at minimum 2-year follow-up.

Conclusions: In this small preliminary international series of pediatric patients with spinal deformity, the inclusion of subaxial cervical pedicle screws in constructs that span the cervicothoracic junction resulted in good clinical and radiographic outcomes without major complications. Subaxial cervical spine pedicle screws provide enhanced biomechanical stability and may eliminate the need for additional anterior support in pediatric patients.