title: Callus patterns in femur lengthening using a monolateral external fixator.
abstract: OBJECTIVE
  We studied the callus pattern seen in femoral lengthening using monolateral external fixator to determine whether callus types and shapes can predict the final outcome of the procedure.
  
  
  METHODS
  The radiographs of 41 cases of femoral lengthening (33 unilateral and 8 bilateral) in 33 patients with a mean age 11.9 years (range 4-22 years) were retrospectively analysed by four observers and classified into different shapes and types in concordance with the Ru Li classification. The classification was tested for concurrence and reproducibility by inter-observer studies.
  
  
  RESULTS
  An average of 6.2 cm of lengthening (range 3-10.8) was achieved with an external fixator index of 36.5 (range 20.9-55.3). The fusiform type of callus (fixator index 32.04, maturation index 21.6) showed the best result followed by the cylinder type of callus (fixator index 35.7, maturation index 22.3) and the lateral type of callus (fixator index 33.2, maturation index 21.5). However, the concave type of callus showed poor results with a fixator index of 49.4 and a maturation index of 37.1. The homogeneous path showed the best results (fixator index 30.4, maturation index 18.6). The heterogeneous path also showed good results (fixator index 36.4, maturation index 23.9). The mixed path (fixator index 42.5, maturation index 30.8) and the lucent path (fixator index 45.1, maturation index 32.8) showed poor results.
  
  
  CONCLUSIONS
  Analysis of the callus pattern helps the surgeon to predict the outcome of the procedure and guide him in planning any additional interventions if necessary.
authors.affiliation: Department of Orthopaedic Surgery, Rare Diseases Institute, Korea University Medical Centre, Guro Hospital, Guro Gu, #80 Guro dong, 152703 Seoul, South Korea.
authors.forename: Dileep
authors.initials: D
authors.lastname: Isaac
authors.forename: Harry
authors.initials: H
authors.lastname: Fernandez
authors.forename: Hae-Ryong
authors.initials: HR
authors.lastname: Song
authors.forename: Tae-Young
authors.initials: TY
authors.lastname: Kim
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Shyam
authors.forename: Seok-Hyun
authors.initials: SH
authors.lastname: Lee
authors.forename: Jong-Chan
authors.initials: JC
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002146:Bony Callus / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D016267:External Fixators; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D019857:Osteogenesis, Distraction; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018709:Statistics, Nonparametric