(P 350) MONITORING CHANGES IN FEMORAL BONE STRENGTH IN PATIENTS WITH METASTATIC BONE DISEASE TREATED WITH RADIATION THERAPY

Objective: Bone metastasis in the femur often lead to pathologic fractures, significantly impacting patients' quality of life. Prophylactic surgical fixation can prevent these fractures in cases of impending pathologic fractures. A patient-specific CT-based autonomous finite element analysis (AFE) serves as a decision-support tool for quantitative fracture risk assessment. The AFE has been validated in a previous randomized prospective study. This study presents preliminary results of a clinical study using AFE for monitoring patients with lower fracture risk who received radiation therapy for femoral metastasis without surgical intervention.

Methods: Thirty-six patients scheduled for radiotherapy were recruited without altering their therapeutic regimen. AFE of their femurs were performed at 0, 3, 6, and 9 months post-radiation. Eleven patients were excluded from the study (six deceased during follow-up, four refused follow-up, one had a knee implant). Six patients completed the full follow-up, thirteen are still in the follow-up period.

Results: Two out of twenty-five patients progressed to surgery with sequential AFE's measuring decreasing bone strength. Two patients required surgery due to increased pain without changes in AFE bone strength. None of the thirteen in the follow-up stage fractured. One patient had a pathological fracture that was not identified by the AFE, and one patient underwent a prophylactic surgery of the distal femur although the AFE predicted low risk but surgeon reported a weak bone. One patient, who had decreasing AFE measurements, refused surgery and subsequently suffered a fracture.

Conclusion: Monitoring changes in femoral strength following radiation therapy using AFE enhances safety by reducing fracture risk in patients in metastatic disease. Fracture risk can be quantified and prevented with prophylactic surgery when necessary.