Analysis of Bone Quality in Patients with 1-year Survival following Spinal Fusion for Oncologic Disease

Introduction: Spine oncology patients undergo significant antineoplastic treatments that impact fusion after spine surgery. Due to a high degree of mortality in spine oncology patients, there is a paucity of published data describing long-term fusion rate and quality. We present radiographic bone quality data for patients with a minimum of 1-year survival who underwent spinal fusion secondary to treatment of metastatic spine disease.

Methods: Patients with metastatic spine disease were collected from a single institution between 2012 and 2022. Included patients had instrumented spinal fusion as part of oncologic treatment, minimum of one year follow up, and post operative CT scan at minimum one year. Retrospective chart review was performed collecting demographic, treatment, and radiographic data. Statistical analysis was performed using the Student T-Test and Fishers Exact T-Test.

Results: There were 87 patients presenting with a variety of metastatic diseases who met inclusion criteria. Demographics for this cohort included a median age of 61.6 (32-89) years old, 44.2% male, and a median construct length of 6 (3-12) levels. There was a significant difference in average Hounsfield units in the posterolateral elements of the spine for patients demonstrating evidence of bony fusion at one year, (419.4) compared to those remaining unfused, (303.6) (p=0.0079). Patients who underwent post-operative radiation or chemotherapy did not have significant differences in rates of fusion, as measured on CT, at one year compared to those who didn’t receive comparative treatment, p=0.407 and p=0.356 respectively.

Conclusion : There is a significant positive association between Hounsfield units on 1 year post operative CT scan and fusion status at 1 year. Administration of radiation therapy and chemotherapy did not appear to impact fusion status and should not be restricted post operatively. Priority should be placed on managing the burden of disease in patients presenting with oncologic disease of the spine.