Resident Department of Neurosurgery, Medical University of Innsbruck
Introduction: Spinal instrumentation is increasingly confronted with mechanical complications (MC) requiring revision surgery due to its growing use in the elderly patient population. Little attention has been paid to the underlying diseases of these patients, which may form the indirect cause of these complications. The aim of this work is to define and evaluate preoperative risk factors for the emergence of MC.
Methods: A retrospective cohort of 538 patients treated with lumbar instrumentation was recruited for this retrospective study. In addition to possible patient-related risk factors (BMI, age, previous disease, premedication), preoperative CT-measured bone density (BMDCT) was assessed. The primary endpoint was defined as any form of mechanical complication in the 2-year postoperative course.
Results: We were able to include 195 patients (84 men, 111 women) for this retrospective analysis. 343 patients have been excluded due to insufficient imaging or clinical data. The median age was 60 years (Inter-quartile range: 50, 71). There were significantly lower BMDCT values for patients with diabetes (p=0.003), COPD (p=0.036), previous stroke (p=0.049), smoking history (p < 0.001) and patients with multiple pre-existing conditions known to influence bone density (p=0.001). Patients on proton pump inhibitors (p=0.025), glucocorticoids (p=0.05), SSRIs (p=0.014), and diuretics (p=0.04) had lower BMDCT compared to patients without these medications. Patients with increased BMI suffered significantly more often from screw loosening (p=0.024) while patients with decreased BMDCT suffered significantly more often from postoperative insufficiency fractures (p=0.043).
Conclusion : The multiple pre-existing conditions and premedication of many patients scheduled for spine surgery can have a significant impact on the postoperative outcome. In addition to a detailed work-up of possible reversible factors, bone densitometry using lumbar CT scans is an efficient method for a rough evaluation of osseous quality.
