Inhibition of Autograft Bone Resorption by Antibone Resorptive Agents After Spinal Reconstruction Surgery for Extensive Cervical Chondrosarcoma: A Case Report with a 10-Year Follow-Up.

Background: For the surgical treatment of spinal malignant tumor, spinal reconstruction with bone graft and instrumentation is necessary after tumor resection, but postoperative complications, including grafted bone resorption, may arise.

Case Description: A 42-year-old Asian woman presented with neck pain, tumorous masses on the neck, and left arm pain. Magnetic resonance imaging and computed tomography of the cervical spine showed extensive malignant spinal tumor. Histological examination of tumor biopsy revealed grade I chondrosarcoma. Complete resection of the tumor was performed using an anterior-posterior approach, followed by anterior iliac bone grafting and posterior spinal instrumentation. No tumor recurrence was observed on magnetic resonance imaging at final follow-up after 10 years. However, grafted bone resorption was identified immediately after surgery due to stress shielding by robust spinal instrumentation. To inhibit resorption of grafted bone, the bisphosphonate minodronate was administered for 5 years from 3 years postoperatively, before being replaced by denosumab from 8 years postoperatively. After use of these antibone resorptive agents, grafted bone resorption stopped.

Conclusions: Anteriorly grafted bone resorption due to stress shielding may occur after reconstructive cervical spine surgery with robust posterior spinal instrumentation. Bisphosphonates and denosumab may be considered to inhibit grafted bone resorption.