Novel Technology to Improve Prediction of Impending Pathological Fractures in Patients with Femoral Metastases

Deciding which patients with skeletal metastasis in the femur will fracture and may benefit from prophylactic fixation is based on Mirels’ criterion and clinical experience. Both suffer from poor specificity. A novel technology, patient-specific CT-based high-order finite element (FE) models of femur, provides an accurate estimate of the risk of pathological fracture. These analyses account for the exact geometry and inhomogeneous material properties, are created in a semi-automated manner and have been validated by biomechanical studies on cadaveric femurs with metastasis.

The purpose of this study was to retrospectively analyze CT scans of 33 patients with impending femur fractures from metastatic disease scheduled for prophylactic surgery.

We estimate that 34.2% (CI 95%) of the patients that were operated for an impending fracture may not have needed stabilization at that time. Five of the patients who were scheduled for prophylactic surgery based on the Mirels’ score due to an impending fracture, were eventually not operated on for various other reasons, did not yet fracture. In four of them, the p-FEA predicted a low risk of fracture.

This retrospective FEA outcome is the first clinical application of this tool and sets the basis for a prospective study which will utilize this novel technology in the decision protocol for prophylactic fixation surgery in patients with femoral metastases.