title: Limb Lengthening in Patients with Achondroplasia.
abstract: OBJECTIVE
  Although bilateral lower-limb lengthening has been performed on patients with achondroplasia, the outcomes for the tibia and femur in terms of radiographic parameters, clinical results, and complications have not been compared with each other. We proposed 1) to compare the radiological outcomes of femoral and tibial lengthening and 2) to investigate the differences of complications related to lengthening.
  
  
  METHODS
  We retrospectively reviewed 28 patients (average age, 14 years 4 months) with achondroplasia who underwent bilateral limb lengthening between 2004 and 2012. All patients first underwent bilateral tibial lengthening, and at 9-48 months (average, 17.8 months) after this procedure, bilateral femoral lengthening was performed. We analyzed the pixel value ratio (PVR) and characteristics of the callus of the lengthened area on serial radiographs. The external fixation index (EFI) and healing index (HI) were computed to compare tibial and femoral lengthening. The complications related to lengthening were assessed.
  
  
  RESULTS
  The average gain in length was 8.4 cm for the femur and 9.8 cm for the tibia. The PVR, EFI, and HI of the tibia were significantly better than those of the femur. Fewer complications were found during the lengthening of the tibia than during the lengthening of the femur.
  
  
  CONCLUSIONS
  Tibial lengthening had a significantly lower complication rate and a higher callus formation rate than femoral lengthening. Our findings suggest that bilateral limb lengthening (tibia, followed by femur) remains a reasonable option; however, we should be more cautious when performing femoral lengthening in selected patients.
authors.affiliation: Institute for Rare Diseases and Department of Orthopedic Surgery, Korea University Medical Center, Guro Hospital, Seoul, Korea.
authors.forename: Kwang-Won
authors.initials: KW
authors.lastname: Park
authors.affiliation: Institute for Rare Diseases and Department of Orthopedic Surgery, Korea University Medical Center, Guro Hospital, Seoul, Korea.
authors.forename: Rey-an Niño
authors.initials: RA
authors.lastname: Garcia
authors.affiliation: Institute for Rare Diseases and Department of Orthopedic Surgery, Korea University Medical Center, Guro Hospital, Seoul, Korea.
authors.forename: Chastity Amor
authors.initials: CA
authors.lastname: Rejuso
authors.affiliation: Institute for Rare Diseases and Department of Orthopedic Surgery, Korea University Medical Center, Guro Hospital, Seoul, Korea.
authors.forename: Jung-Woo
authors.initials: JW
authors.lastname: Choi
authors.affiliation: Institute for Rare Diseases and Department of Orthopedic Surgery, Korea University Medical Center, Guro Hospital, Seoul, Korea. songhae@korea.ac.kr.
authors.forename: Hae-Ryong
authors.initials: HR
authors.lastname: Song
mesh_terms: D000130:Achondroplasia / Q000601:surgery*; D000293:Adolescent; D001852:Bone Lengthening / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D008297:Male; D011859:Radiography; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult
keywords: Achondroplasia; bone lengthening