Assessment of Proximal Junctional Kyphosis and Shoulder Balance With Proximal Screws versus Hooks in Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

A retrospective review of a prospectively collected multicenter database. To assess the effect of proximal hooks versus screws on proximal junctional kyphosis (PJK) as well as shoulder balance in otherwise all pedicle screw (>80%) posterior spinal fusion (PSF) constructs in adolescent idiopathic scoliosis (AIS). Less rigid forms of fixation at the top of constructs in degenerative lumbar PSF have been postulated to decrease the risk of PJK. A multicenter AIS surgical database was reviewed to identify all patients who underwent PSF with all pedicle screw (>80%) constructs and minimum 2-year follow-up. Patients in the "hook" group had two hooks used at the top of the construct, whereas the "screw" group used only pedicle screws at all levels. A total of 354 patients were identified, 274 (77%) in the screw group, and 80 (23%) in the hook group. There were no significant preoperative differences with regards to curve type, coronal/sagittal Cobb angle, or curve flexibility for either group. At 2 years post-op, the coronal Cobb correction was similar for both groups (60%). There was no difference in correction of shoulder asymmetry and T1 rib angle, including when the groups were matched for preoperative shoulder balance. PJK, defined as the sagittal Cobb angle between the uppermost instrumented and uninstrumented vertebrae, was similar for the screw versus hook group as well (7.1° vs. 6.2°, P = 0.2). The use of different anchors (pedicle screws vs. hooks) at the top of an otherwise all pedicle screw PSF construct for AIS did not have any significant bearing on the correction of shoulder asymmetry and coronal Cobb angle at 2 years postoperative. There was also no significant difference in the magnitude of PJK or incidence of marked PJK (>15°) between either group at 2 years. 3.