title: Pressurization of the metastatic femur during prophylactic intramedullary nail fixation.
abstract: 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.
authors.affiliation: Orthopaedic Biomechanics Laboratory, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Roth
authors.forename: Mary M
authors.initials: MM
authors.lastname: Rebello
authors.forename: Hans
authors.initials: H
authors.lastname: Kreder
authors.forename: Cari M
authors.initials: CM
authors.lastname: Whyne
mesh_terms: D000399:Air Pressure; D000704:Analysis of Variance; D002102:Cadaver; D004620:Embolism, Fat / Q000209:etiology / Q000517:prevention & control; D005264:Femoral Fractures / Q000209:etiology / Q000517:prevention & control*; D005266:Femoral Neoplasms / Q000150:complications / Q000556:secondary / Q000601:surgery*; D005594:Fracture Fixation, Intramedullary / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D005598:Fractures, Spontaneous / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D007430:Intraoperative Care / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D016014:Linear Models; D008365:Manometry / Q000295:instrumentation / Q000379:methods; D016343:Monitoring, Intraoperative; D009360:Neoplastic Cells, Circulating; D012307:Risk Factors; D015607:Stents / Q000592:standards*; D013997:Time Factors; D014160:Transducers, Pressure; D016896:Treatment Outcome