Pressurization of the metastatic femur during prophylactic intramedullary nail fixation

Background. Venting during prophylactic nailing of metastatic femoral lesions may decrease intramedullary pressures and the risk of fat and tumor embolization. This study aimed to quantify maximum intramedullary pressure levels and durations, and to examine tumor displacement during prophylactic reamed intramedullary nailing of vented and nonvented metastatically involved femora. Methods: Proximal metastatic defects were simulated in six pairs of cadaveric femora and prophylactically treated using reamed intramedullary nailing with or without proximal and distal vents. Maximum pressures, durations of pressure exceeding embolic threshold levels (25 and 200 mm Hg), and tumor displacement were recorded. Results: Maximum pressures and durations of pressure exceeding embolic thresholds decreased more than 50% with venting (p < 0.05). Distal pressures surpassed the 25-mm Hg threshold even with venting. Post-test sectioning showed increased tumor disbursement in vented specimens. Conclusions: Venting reduces pressurization during prophylactic reamed intramedullary nailing of femoral metastases, but may increase the spread of tumor to extraskeletal tissue if vented tissue is not contained.