title: Inferior subluxation of the fibular head following tibial lengthening with a unilateral external fixator.
abstract: BACKGROUND
  Inferior subluxation of the proximal part of the fibula has been reported to occur with distraction osteogenesis of the tibia; however, the clinical sequelae of this subluxation are unknown. The purpose of this study was to evaluate inferior subluxation of the proximal part of the fibula and its possible clinical implications in patients who had undergone tibial lengthening by distraction osteogenesis with use of a unilateral external fixator.
  
  
  METHODS
  Thirty tibiae in seventeen patients with a variety of conditions underwent tibial lengthening by distraction osteogenesis with use of a unilateral external fixator and were followed clinically and radiographically for a mean of two years and ten months (range, two to four years). Ten patients were female and seven were male. Their mean age at the time of the surgery was seventeen years (range, eight to twenty-five years). The mean tibial lengthening was 8.1 cm (range, 3.5 to 13 cm).
  
  
  RESULTS
  An inferior shift of the fibular head in relation to the tibia was evident in all cases. The shift, which ranged from 0.4 to 3.3 cm, was proportionally related to the amount of tibial lengthening. This type of subluxation is probably attributable to the tension that is exerted by the intact interosseous membrane during the distraction as well as to the tension of the regenerated bone of the fibula and the fact that the fibula itself is not fixed or directly lengthened by the external fixator.
  
  
  CONCLUSIONS
  It appears that inferior subluxation of the fibula is a common phenomenon in patients undergoing tibial lengthening by distraction osteogenesis with use of a unilateral external fixator. However, no clinical symptoms or findings related to the inferior subluxation of the fibula were found in our series.
authors.affiliation: 1st Orthopaedic Department, Aristotelian University of Thessaloniki, Thessaloniki, Greece. ipphatz@yahoo.gr
authors.forename: Ippokratis
authors.initials: I
authors.lastname: Hatzokos
authors.forename: Androniki
authors.initials: A
authors.lastname: Drakou
authors.forename: Anastasios
authors.initials: A
authors.lastname: Christodoulou
authors.forename: Ioannis
authors.initials: I
authors.lastname: Terzidis
authors.forename: John
authors.initials: J
authors.lastname: Pournaras
mesh_terms: D000293:Adolescent; D000328:Adult; D001852:Bone Lengthening / Q000009:adverse effects*; D002648:Child; D004867:Equipment Design; D016267:External Fixators; D005260:Female; D005360:Fibula; D006801:Humans; D031221:Knee Dislocation / Q000000981:diagnostic imaging / Q000209:etiology*; D008297:Male; D011859:Radiography; D013977:Tibia / Q000601:surgery*