Lytic Lesions in the Femoral Neck: Importance of Location and Evaluation of a Novel Minimally Invasive Repair Technique

Proximal femoral metastases can lead to pathologic fracture. The goals of this study were to improve guidelines for assessing pathologic hip fracture risk by quantifying the effect of location of femoral neck metastases on hip strength under single-limb stance loading and to evaluate the effectiveness of a proposed minimally invasive surgical repair technique for restoring hip strength. Twelve matched pairs of human cadaveric proximal femora were used to create a total of 564 finite element models before and after introduction and repair of simulated lytic defects, modeled as spherical voids, at various locations within the femoral neck. Defect site greatly affected hip strength (p < 0.001). Defects in the inferomedial aspect of the neck and in the dense trabecular bone near the base of the femoral head had the greatest effect, with hip strengths 23% to 72% and 43% to 64% that of the intact strength, respectively, for 20-mm diameter defects. Even so, the proposed percutaneous repair technique restored static strength of femora with defects at all of the studied locations. These findings may lead to a reduction in the number of patients who suffer a preventable pathologic fracture, a decreased likelihood of unnecessary surgery, and a less invasive prophylactic surgical procedure.