title: Revision Distal Femoral Arthroplasty With the Compress(®) Prosthesis Has a Low Rate of Mechanical Failure at 10 Years.
abstract: BACKGROUND
  Patients with failed distal femoral megaprostheses often have bone loss that limits reconstructive options and contributes to the high failure rate of revision surgery. The Compress(®) Compliant Pre-stress (CPS) implant can reconstruct the femur even when there is little remaining bone. It differs from traditional stemmed prostheses because it requires only 4 to 8 cm of residual bone for fixation. Given the poor long-term results of stemmed revision constructs, we sought to determine the failure rate and functional outcomes of the CPS implant in revision surgery.
  
  
  OBJECTIVE
  (1) What is the cumulative incidence of mechanical and other types of implant failure when used to revise failed distal femoral arthroplasties placed after oncologic resection? (2) What complications are characteristic of this prosthesis? (3) What function do patients achieve after receiving this prosthesis?
  
  
  METHODS
  We retrospectively reviewed 27 patients who experienced failure of a distal femoral prosthesis and were revised to a CPS implant from April 2000 to February 2013. Indications for use included a minimum 2.5 mm cortical thickness of the remaining proximal femur, no prior radiation, life expectancy > 10 years, and compliance with protected weightbearing for 3 months. The cumulative incidence of failure was calculated for both mechanical (loss of compression between the implant anchor plug and spindle) and other failure modes using a competing risk analysis. Failure was defined as removal of the CPS implant. Followup was a minimum of 2 years or until implant removal. Median followup for patients with successful revision arthroplasty was 90 months (range, 24-181 months). Functional outcomes were measured with the Musculoskeletal Tumor Society (MSTS) functional assessment score.
  
  
  RESULTS
  The cumulative incidence of mechanical failure was 11% (95% confidence interval [CI], 4%-33%) at both 5 and 10 years. These failures occurred early at a median of 5 months. The cumulative incidence of other failures was 18% (95% CI, 7%-45%) at 5 and 10 years, all of which were deep infection. Three patients required secondary operations for cortical insufficiency proximal to the anchor plug in bone not spanned by the CPS implant and unrelated to the prosthesis. Median MSTS score was 27 (range, 24-30).
  
  
  CONCLUSIONS
  Revision distal femoral replacement arthroplasty after a failed megaprosthesis is often difficult as a result of a lack of adequate bone. Reconstruction with the CPS implant has an 11% failure rate at 10 years. Our results are promising and demonstrate the durable fixation provided by the CPS implant. Further studies to compare the CPS prosthesis and other reconstruction options with respect to survival and functional outcomes are warranted.
  
  
  METHODS
  Level IV, therapeutic study.
authors.affiliation: Orthopaedic Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.
authors.forename: Melissa N
authors.initials: MN
authors.lastname: Zimel
authors.affiliation: Institute of Orthopedics Carlos E. Ottolenghi, Italian Hospital of Buenos Aires, Buenos Aires, Argentina.
authors.forename: German L
authors.initials: GL
authors.lastname: Farfalli
authors.affiliation: Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Zindman
authors.affiliation: Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Elyn R
authors.initials: ER
authors.lastname: Riedel
authors.affiliation: Division of Orthopaedic Oncology, Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Carol D
authors.initials: CD
authors.lastname: Morris
authors.affiliation: Orthopaedic Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Boland
authors.affiliation: Orthopaedic Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA. healeyj@mskcc.org.|Department of Orthopaedic Surgery, Weill Cornell Medical College, New York, NY, USA. healeyj@mskcc.org.
authors.forename: John H
authors.initials: JH
authors.lastname: Healey
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D000069343:Bone-Implant Interface; D020878:Device Removal; D004185:Disability Evaluation; D005260:Female; D005266:Femoral Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005269:Femur / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D010027:Osteotomy; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D020127:Recovery of Function; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D013314:Stress, Mechanical; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult