Impact of Preoperative Teriparatide Use on Proximal Junctional Kyphosis Prevention in Osteopenic/Osteoporotic...

Background/Objectives: Poor bone quality significantly increases the risk of mechanical complications after adult spinal deformity (ASD) surgery, including proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). Although teriparatide enhances bone quality, its effectiveness in preventing junctional complications after extensive correction remains unclear. This study investigated whether preoperative teriparatide administration reduces the incidence of PJK and PJF in patients with compromised bone quality undergoing ASD surgery. Methods: This retrospective cohort study reviewed 292 patients (T-score < -1.0) who underwent ASD surgery between 2015 and 2023. Patients were divided into teriparatide (n = 59) and non-teriparatide (n = 233) groups. Propensity score matching (1:2 ratio) was performed using six covariates: age, preoperative pelvic incidence minus lumbar lordosis, preoperative T1 pelvic angle, upper instrumented vertebra (UIV) cementing, UIV screw angle, and fusion length, yielding 153 matched patients (52 teriparatide, 101 non-teriparatide). Results: After matching, all baseline characteristics were statistically similar, with no significant differences. The incidence of PJK and PJF did not differ significantly between the teriparatide and non-teriparatide groups (44.2% vs. 52.5%, p = 0.426; 9.6% vs. 9.9%, p = 1.000), nor did PJK subtype distribution (bony vs. soft-tissue). Multivariate analysis identified older age (odds ratio [OR] = 1.058), higher American Society of Anesthesiologists score (OR = 2.603, p = 0.002), UIV at the thoracolumbar junction (OR = 2.786), and greater postoperative thoracic kyphosis (OR = 1.044) as independent risk factors for PJK. Teriparatide use was not an independent predictor (OR = 0.872). Conclusions: Preoperative teriparatide did not significantly reduce the incidence of PJK or PJF after long-segment fusion for ASD. These findings suggest that improving bone quality alone is insufficient to prevent junctional complications, which are driven by complex biomechanical and patient-related factors inherent to extensive deformity correction.