title: "Reverse" hip spacer for massive distal femur defects in peri-prosthetic knee infections.
abstract: BACKGROUND
  Bone loss in the distal femur is a common problem in knee revision surgeries. The problem is exacerbated in the context of an active infection. In extreme cases this bone loss could compromise the feasibility of a two-stage exchange protocol using dynamic spacers due to the inherent instability of this type of spacers. Use of a hip prefabricated spacer in a "reverse" way forming a ball-and- socket joint is a therapeutic option in cases of massive bone defect and infection.
  
  
  METHODS
  A retrospective review was performed of our institutional database to identify all cases of massive distal femoral defect in which this technique was used from January 2010 to December 2013. A record was made of the epidemiological data, characteristics of the infection (clinical and microbiological), and adverse event during the spacer stage. The main end-point was the infection eradication rate (minimum: 18 months of follow-up). The complications associated with the technique were also assessed. Finally, each patient completed a visual analogue pain scale, and a satisfaction questionnaire (SAPS).
  
  
  RESULTS
  This technique was successfully used in six cases so far, controlling the infection in all cases. Mean femoral defect was 117cm (range: 32-191cm). Mean time with spacer was 7.6 months, with no major complications. All but one patient reached second stage reconstruction with a mega-prosthesis, and mean time since second stage was 34.7 months. All patients stated high levels of satisfaction with the technique employed, as well as and low pain scores (mean visual analogue pain scale: 1; range: 0-4).
  
  
  CONCLUSIONS
  A reproducible and safe technique is described. Patients report a high level of satisfaction with the procedure, and there were no cases of recurrence of the infection after a minimum follow-up of 18 months.
authors.affiliation: Cirugía Ortopédica, Centro Médico Delfos, Hospital Teknon, Barcelona, España.
authors.forename: X
authors.initials: X
authors.lastname: Flores
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario Vall d'Hebron, Barcelona, España. Electronic address: matiasvgc@gmail.com.
authors.forename: M
authors.initials: M
authors.lastname: Vicente
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario Vall d'Hebron, Barcelona, España.
authors.forename: S
authors.initials: S
authors.lastname: Haddad
authors.affiliation: Unidad de Patología Séptica y Cirugía Reconstructiva del Aparato Locomotor, Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario Vall d'Hebron, Barcelona, España.
authors.forename: C
authors.initials: C
authors.lastname: Amat
authors.affiliation: Unidad de Patología Séptica y Cirugía Reconstructiva del Aparato Locomotor, Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario Vall d'Hebron, Barcelona, España.
authors.forename: L
authors.initials: L
authors.lastname: Carrera
authors.affiliation: Unidad de Patología Séptica y Cirugía Reconstructiva del Aparato Locomotor, Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario Vall d'Hebron, Barcelona, España.
authors.forename: P S
authors.initials: PS
authors.lastname: Corona
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods; D004927:Escherichia coli Infections / Q000473:pathology / Q000601:surgery*; D005260:Female; D005269:Femur / Q000473:pathology* / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000473:pathology / Q000601:surgery*; D012086:Reoperation / Q000295:instrumentation* / Q000379:methods; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome
keywords: Artroplastia de recambio en dos tiempos; Bone defect; Defectos óseos; Dynamic spacer; Espaciador dinámico; Infección periprotésica de rodilla; Knee periprosthetic joint infection; Two-stage exchange arthroplasty