Effect of zoledronic acid on lumbar spinal fusion in osteoporotic patients

To investigate the effect of zoledronic acid (ZA) on lumbar spinal fusion in patients with osteoporosis. This retrospective study includes 94 osteoporotic patients suffering from lumbar degenerative diseases or lumbar fracture who underwent lumbar spinal fusion in our institution from January 2013 to August 2014. They were divided into ZA group and control group according to whether the patient received ZA infusion or not. The patients in ZA group were given 5 mg intravenous ZA at the 3rd-5th days after operation. All patients took daily oral supplement of 600 mg calcium carbonate and 800 IU vitamin D during the follow-up after operation. The Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), and Short Form 36 (SF-36) scores were recorded preoperatively and post-operatively to evaluate the clinic outcomes; the spinal fusion was assessed by X-ray or CT Scan. 64 patients finished the final follow-up, including 30 patients in ZA group and 34 patients in control group. No significant difference was observed in gender, age, and preoperative BMI VAS, ODI, and SF-36 scores between the two groups (P > 0.05). The post-operative VAS and ODI scores decreased rapidly at 3 and 6 months, but rose back slightly at 12 and 24 months in both groups. On the contrary, post-operative SF-36 scores increased rapidly at 3 and 6 months, while fell back slightly at 12 and 24 months, with a statistically significant difference between the two groups at 12 months, but not at 3 and 6 month post-operation. The spinal fusion rate in ZA group was 90% at 6 months, 92% at 12 months, while it was 75% at 6 months, 92.86% at 12 months in control group, significantly different between the two groups at 12 months, but not at 6 months. In the whole follow-up period, adjacent vertebral compressing fracture occurred in five patients in control group, none in ZA group. No pedicle screw loosening was observed in ZA group, with six in control group. Zoledronic acid accelerates spinal fusion, shortens the time of fusion without changing fusion rate, and also decreases the risk of adjacent vertebral compressing fracture and the rate of pedicle screw loosening, resulting in the improvement of clinical outcomes and quality of life.