Background: Metastatic bone disease is a major cause of morbidity in patients with advanced cancer, often resulting in pathologic fractures that significantly diminish quality of life. Intramedullary nail (IMN) fixation remains a crucial treatment for both impending and completed fractures. With advancements in targeted therapies extending patient survival, the risk of implant failure has increased.

Objective: We aim to identify patient-specific risk factors that contribute to intramedullary nail failure.

Methods: A retrospective review was performed of patients with impending or completed pathologic fractures of the femur. Patients were identified using procedure codes for IMN fixation. Clinical and surgical data, including patient demographics, primary cancer type, fracture classification, prior treatments (chemotherapy or radiotherapy), and implant details were extracted from medical records. Descriptives were reported as N(%) or median(IQR). Logistic regression analysis are reported as odds ratios (OR) with associated 95%-confidence intervals (CI).

Results: 150 patients with 162 nails were identified. Of the 150 patients, 62.7% (94/150) were female with a mean age of 59.6±18.3 and mean follow-up time of 15 months. The most common cancer types for patients included 30.0% (45/150) with breast cancer, 20% (30/150) hematologic cancer, 18% (27/150) genitourinary cancer, 12% (18/150) lung cancer, 5.3% (8/150) GI/hepatobiliary cancer, and 22.7% (34/150) belonging to other solid tumors/sarcoma subtypes. 11.7% (19/162) of IMN fixations required subsequent revisions with 73.7% (14/19) of patients with revisions having proximal femur lesions as the site of original metastasis. Additionally, 68.4% (13/19) of patients with revisions received either neoadjuvant or adjuvant radiotherapy and was associated with increased likelihood of revision (OR: 4.78, 95%CI: 1.30-17.5, p=0.018). Pre-operative systemic therapy, cancer type, and site of metastasis were not associated with increased risk of revision.

Conclusions: Failures were more common in patients that received radiotherapy. No difference in revision risk was noted by cancer type or site of metastasis.