Increased Number of Medical Comorbidities Associated With Increased Risk of Presenting With Pathological Femur Fracture in Metastatic Bone Disease.

Background: Many cancers metastasize to bone and may lead to pathologic fracture or impending pathologic fracture. Prophylactically stabilizing bones before fracture has been shown to be more cost-effective with improved outcomes. Many studies have examined risk factors for pathological fracture, with radiographic and functional pain data serving as predominant indicators for surgery. Conditions associated with poor bone health and increased risk of fracture in the non-oncologic population, including diabetes mellitus, chronic obstructive pulmonary disease (COPD), cardiovascular disease, renal disease, smoking, corticosteroid use, and osteoporosis, have not been studied in the context of metastatic disease. Characterization of these factors could help providers identify candidates for prophylactic stabilization thereby reducing the number of completed pathological fractures. Methods: 298 patients over the age of 40 with metastatic bone disease of the femur treated between 2010-2021 were retrospectively identified. Patients without complete medical documentation or with non-metastatic diagnoses were excluded. 186 patients met inclusion and exclusion criteria, including 74 patients who presented with pathological femur fracture and 112 patients who presented for prophylactic stabilization. Patient demographics and comorbidities including diabetes mellitus, COPD, cardiovascular disease, renal disease, osteoporosis, active tobacco or corticosteroid use, and use of anti-resorptive therapy were collected. Descriptive statistics were compiled, with univariable analysis by Mann-Whitney or chisquared testing. Multiple logistic regression was then performed to identify the most significant patient variables for presenting with completed fracture. Results: On univariable analysis, patients with COPD were more likely to present with pathologic fracture (19/32 [59%] compared to 55/154 [36%], p = 0.02). A trend emerged for patients with an increasing number of comorbidities (28/55 [51%] for 2+ comorbidities compared to 18/61 [29%] with zero comorbidities, p = 0.06). On multivariable analysis, patients with two or more comorbidities (OR: 2.49; p=0.02) were more likely to present with a femur fracture. Conclusion: This analysis suggests that those with an increasing number of comorbidities may be at increased risk for pathologic fracture. This study raises the possibility that patient factors and/ or comorbidities alter bone strength and/or pain experiences and may guide orthopaedic oncologists weighing prophylactic stabilization of femur lesions.