title: Outcome of expandable prostheses in children.
abstract: BACKGROUND
  Expandable prostheses offer the advantages of limb-salvage and limb-length equality at skeletal maturity. However, what is the cost for achieving that goal, and in how many children this is achieved?
  
  
  METHODS
  We present 32 children (16 boys and 16 girls; mean age, 9 y) with bone sarcomas of the femur treated with limb salvage using expandable prostheses. The Kotz Growing prosthesis and the noninvasive Repiphysis and Stanmore expandable prostheses were used. The mean follow-up was 49 months. Survival analysis of the children and primary implants and functional evaluation were performed.
  
  
  RESULTS
  Survival of the children was 94% and 84% at 48 and 72 months. Survival of the primary prostheses was 78% and 66% at 48 and 72 months; survival was significantly higher only for the Kotz when compared with the Repiphysis prostheses (P=0.026). The rate of implant-related complications was 51.3%; 9 prostheses (23%) were revised because of aseptic loosening, infection, and breakage. A mean total lengthening of 28 mm (4 to 165 mm) was achieved by 84 procedures (2.6 procedures/patient). Three of the 9 children who reached skeletal maturity had limb-length equality and 6 discrepancy of 15 to 30 mm. The mean Musculoskeletal Tumor Society score was excellent (79%) without a significant difference between the type of prostheses (P=0.934).
  
  
  CONCLUSIONS
  The Kotz Growing prosthesis, although it requires an open lengthening procedure, has shown higher survival when compared with the noninvasive Repiphysis prosthesis. However, the total lengthening remains small, and the complications rates are high even with the noninvasive prostheses.
authors.affiliation: Department of Orthopedics, Istituto Ortopedico Rizzoli, University of Bologna, Bologna, Italy. pietro.ruggieri@ior.it
authors.forename: Pietro
authors.initials: P
authors.lastname: Ruggieri
authors.forename: Andreas F
authors.initials: AF
authors.lastname: Mavrogenis
authors.forename: Elisa
authors.initials: E
authors.lastname: Pala
authors.forename: Matteo
authors.initials: M
authors.lastname: Romantini
authors.forename: Marco
authors.initials: M
authors.lastname: Manfrini
authors.forename: Mario
authors.initials: M
authors.lastname: Mercuri
mesh_terms: D000293:Adolescent; D001852:Bone Lengthening / Q000295:instrumentation*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005266:Femoral Neoplasms / Q000601:surgery*; D006801:Humans; D007870:Leg Length Inequality / Q000601:surgery*; D023821:Limb Salvage / Q000295:instrumentation*; D008297:Male; D012516:Osteosarcoma / Q000601:surgery*; D019736:Prostheses and Implants; D011474:Prosthesis Design; D012189:Retrospective Studies; D016896:Treatment Outcome