(P 108) FIXATION OF IMPENDING OR PATHOLOGIC FRACTURES DUE TO METASTATIC DISEASE WITH CARBON FIBER INTRAMEDULLARY NAILS-A PROPENSITY-SCORE MATCHED COST ANALYSIS

Objective: Carbon fiber (CF) implants are increasingly used in musculoskeletal oncology for treating metastatic bone disease. Several studies have shown their comparable clinical outcomes to metal implants and improved visualization. However, while these implants demonstrate favorable technical characteristics for orthopaedic stabilization, cost comparisons are lacking in the current literature. Given the increasing incidence of metastatic disease, there is a growing need for fixation or prophylactic stabilization of impending or pathologic fractures, especially in the femur. Our study aimed to compare the short-term post-operative costs of titanium and CF intramedullary nailing (IMN) for the treatment of femoral metastatic disease.

Methods: We conducted a retrospective study of patients between 2016 and 2020 with impending or completed pathological fractures of the femur due to metastatic bone disease that underwent fixation through IMN. All patients included were older than 18 years old and were treated with either titanium nails or CF nails. Propensity-score matching (PSM) analysis was performed. A one-to-many match using nearest-neighbor matching and a caliper fixed at 0.005. Basic demographic variables were included as well as preoperative Eastern Cooperative Oncology Group (ECOG) scores and preoperative lab values were taken up to 2 weeks prior to index procedure. The type of primary tumor, synchronous presence of visceral or bone metastases, and type of pathological fracture were included. All billable items (including services and implant cost) provided by our institution during the specified time period were collected. The costs extracted were divided by a common denominator to create a representative cost-unit (CU) value for statistical analysis. Due to high mortality rates after a pathological fracture, we restricted analysis to 30 days post-surgery. Final metrics included were daily costs from index surgery to discharge and from index surgery to 30 days post-op, and total costs from index surgery to 30 days post-surgery.

Results: A total of 153 patients with bone metastases underwent intramedullary nailing; 132 patients in the titanium nail group, and 21 in the CF group. After PSM, 87 patients in the titanium nail group and 21 in the CF nail group were analyzed (Table 1). In the PSM cohort, median age was 63 and 68 for the titanium and CF nail groups, respectively (p=0.24). No differences were found in their comorbidity profiles or preoperative lab values. Breast and lung were the most common histologies in the titanium and CF nail groups, respectively. A higher rate of completed fractures was found in the titanium nail group (32%) compared to the CF nail group (5%) (p=0.01). Median daily costs from index surgery to discharge and from index surgery to 30 days post-op were not different between the CF and titanium nail groups (p=0.78 and p=0.99) (Table 2). No difference in median total costs from index surgery to 30 days post-op was found (p=0.79). No significant differences were found in these three metrics when analyzing mean values instead of median values. Cost was also compared using mean and median values in the matched cohort. No differences were found between groups on median daily costs from index surgery to discharge (p=0.86), from index surgery to 30 days post-op (p=0.92) and total costs from index surgery to 30 days post-op (p=0.86) (Table 3). No significant differences were found in these three metrics when analyzing mean values instead of median values. In our matched cohort, in-hospital complications occurred 16% of patients in the titanium nail group and 10% of the CF nail group (p=0.45) (Table 4). Complications within 30 days of discharge occurred at similar rates between the titanium nail group (15%) and CF nail group (14%) (p=0.94). No differences in median length of stay, total length of stay and discharge location were found between groups (p>0.05).

Conclusion: Evaluation of the cost effectiveness of carbon fiber implants for impending or completed pathologic fractures of the femur demonstrates no difference between cost of CF nails compared with metal nails.