title: Long term outcomes of cemented endoprosthetic reconstruction for periarticular tumors of the distal femur.
abstract: BACKGROUND
  In order to achieve an oncological margin during limb salvage surgery for tumors of the distal femur, part or the entire knee joint is frequently sacrificed. Endoprosthetics make limb salvage possible through restoration of a functional extremity. Currently there remains a paucity of data concerning their long-term outcomes and associated risk factors for failure.
  
  
  METHODS
  We identified 152 patients who underwent an endoprosthetic reconstruction for an oncological process of the distal femur between 1972 and 2013. The mean follow-up was 10years. Mean age and body mass index (BMI) were 39years and 25.8 respectively. The most common pathology was osteosarcoma (n=78, 48%). Outcomes were compared to a control group of 20,643 patients undergoing total knee arthroplasty (TKA) for degenerative joint disease (DJD) during the same time period.
  
  
  RESULTS
  The mean five-, 10-, 15-, 20-, and 25-year revision-free survival for an endoprosthesis was 76%, 63%, 51%, 36%, and 28%. Compared to the five-, 10-, 15-, 20-, and 25-year survival of 95%, 90%, 82%, 74%, and 67% for control TKAs (p<0.0001 at all-time points). Overall limb survival was 93%, with 11 patients undergoing amputation. There was no difference in implant survival comparing modular and custom endoprostheses.
  
  
  CONCLUSIONS
  The results of this study show that given the complexity of these operations, the rate of revision surgery following endoprosthetic replacement is high. Nevertheless, the use of these modular reconstructions leads to a high rate of limb salvage (93%) over a 25-year period at our institution.
  
  
  METHODS
  Level III.
authors.affiliation: Mayo Clinic, Department of Orthopedic Surgery, 200 First St. SW, Rochester, MN 55905, United States. Electronic address: houdek.matthew@mayo.edu.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Houdek
authors.affiliation: Mayo Clinic, Department of Orthopedic Surgery, 200 First St. SW, Rochester, MN 55905, United States. Electronic address: wagner.eric@mayo.edu.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Wagner
authors.affiliation: Mayo Clinic, Department of Orthopedic Surgery, 200 First St. SW, Rochester, MN 55905, United States. Electronic address: wilke.benjamin@mayo.edu.
authors.forename: Benjamin K
authors.initials: BK
authors.lastname: Wilke
authors.affiliation: Mayo Graduate School of Medical Education, 200 First St. SW, Rochester, MN 55905, United States. Electronic address: wyles.cody@mayo.edu.
authors.forename: Cody C
authors.initials: CC
authors.lastname: Wyles
authors.affiliation: Mayo Clinic, Department of Orthopedic Surgery, 200 First St. SW, Rochester, MN 55905, United States. Electronic address: taunton.michael@mayo.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Taunton
authors.affiliation: Mayo Clinic, Department of Orthopedic Surgery, 200 First St. SW, Rochester, MN 55905, United States. Electronic address: sim.franklin@mayo.edu.
authors.forename: Franklin H
authors.initials: FH
authors.lastname: Sim
mesh_terms: D000328:Adult; D001859:Bone Neoplasms / Q000401:mortality / Q000601:surgery*; D005260:Female; D005269:Femur; D005544:Forecasting; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D023821:Limb Salvage / Q000379:methods*; D008297:Male; D012516:Osteosarcoma / Q000401:mortality / Q000601:surgery*; D011475:Prosthesis Failure; D019651:Plastic Surgery Procedures / Q000379:methods*; D012086:Reoperation; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D014481:United States / Q000453:epidemiology
keywords: Distal femur; Endoprosthesis; Long-term outcomes; Oncological reconstruction