Effects of Perioperative Teriparatide Treatment on the Hounsfield Unit Values at the Upper Instrumented Vertebra in Adult Spinal Deformity Surgery.

Study Design:Retrospective single-center study. Objective:This study aimed to assess the effects of pre and postoperative teriparatide (TPTD) treatment on Hounsfield units (HU) after surgery for adult spinal deformity (ASD). Summary of Background Data:The most commonly used method for assessing bone mineral density is dual-energy x-ray absorptiometry. HU values at the upper instrumented vertebra (UIV) have been proposed as a surrogate method for assessing bone quality, particularly in patients with ASD. However, the effect of TPTD treatment on vertebral HU values remains unclear. Materials and Methods:We identified 57 consecutive patients with ASD who underwent long-instrumented fusion surgery (>5 vertebrae) between 2014 and 2020. Patients were retrospectively divided into a non-TPTD group (n = 31) and a TPTD group (n = 26). HU measurements were obtained at a level above the UIV (UIV + 1). Changes in the HU value at 1-year postoperatively were compared between the TPTD and non-TPTD groups. The duration of preoperative TPTD was compared between the proximal junctional proximal junctional failure (PJF) and non-PJF groups. Results:Preoperative HU values were significantly lower in the TPTD group than in the non-TPTD group, despite no significant difference in preoperative bone mineral density of the proximal femur between the two groups. Changes in HU values were significantly higher in the TPTD group than in the non-TPTD group (20.8 & PLUSMN; 15.7% vs -2 & PLUSMN; 10.2%, P < 0.001). In the subanalysis of the TPTD group, the duration of preoperative TPTD treatment was significantly shorter in the PJF group than in the non-PJF group (34.7 & PLUSMN; 16.8 days vs 86.9 & PLUSMN; 34.7 days, P = 0.004). Conclusions:Pre and post-operative TPTD treatment increased the average HU value at UIV + 1 by 20.8%. Therefore, more prolonged preoperative TPTD treatment improves bone quality and may help prevent osteoporosis-related complications.