Effect of Zoledronic Acid on the Vertebral Body Bone Mineral Density After Instrumented Intervertebral Fusion in Postmenopausal Women With Osteoporosis

Study Design: Retrospective cohort study. Objectives: To evaluate the effect of zoledronic acid, an anti-osteoporosis treatment, during the perioperative period on vertebral body bone mineral density (BMD) after spinal fusion surgery in postmenopausal women with osteoporosis. Methods: The medical records of postmenopausal patients with osteoporosis who underwent instrumented intervertebral fusion for lumbar degenerative disease between July 2016 and May 2018 were reviewed. Patients with comorbidities or condition which might affect bone metabolism were excluded. Forty-six patients did not receive anti-osteoporosis treatment before surgery and during the postoperative follow-up (untreated group). Another 46 patients who was treated with zoledronic acid perioperatively were matched for age and body mass index to patients in the untreated group. Preoperative and postoperative dual-energy X-ray absorptiometry (DEXA) records and lumbar BMD values of the involved spinal segments and of the cephalad levels, as well as of the femoral neck were recorded. Results: A significant decrease of cephalad vertebral BMD values was observed in the untreated group (-11.47%, P < 0.001), with a slight decrease of the femoral neck (-1.28%, P > 0.05). Zoledronic acid prevented rapid bone loss after instrumented intervertebral fusion surgery, with a bone loss in the cephalad levels of -0.76 +/- 4.71% compared to -11.47 +/- 16.45% in the untreated group (P < 0.001). while the change in BMD of the femoral neck in the treated group was 1.52 +/- 5.88% compared to -1.28 +/- 6.58% in the untreated group (P = 0.036). Conclusions: Perioperative zoledronic acid treatment may offer protection against a significant decrease in BMD of cephalad vertebrae after spinal fusion surgery among postmenopausal women with osteoporosis.