title: Correction of ankle valgus by hemiepiphysiodesis using the tension band principle in patients with multiple hereditary exostosis.
abstract: BACKGROUND
  Ankle valgus is a common deformity in patients with multiple hereditary exostoses (MHE) and a potential risk factor for early degenerative arthritis. In children, medial hemiepiphysiodesis of the distal tibia is a relatively simple surgical technique used to correct this deformity. We present here the first results of applying this procedure using the eight-Plate guided growth system (eight-Plate) for growth guidance.
  
  
  METHODS
  Between 2006 and 2011 we performed hemiepiphysiodesis of the distal medial tibia in 30 ankles of 18 children with MHE using the eight-Plate. Weight-bearing total leg radiographs were obtained preoperatively, during follow-up and at the time of implant removal or when the distal tibial physis had closed. The lateral distal tibia angle (LDTA) was measured and fibular shortening assessed using the Malhotra classification. To evaluate the effect of hemiepiphysiodesis, we correlated the LDTA with age.
  
  
  RESULTS
  The mean age at time of surgery was 12.6 (range 9.5-15.0) years, and the mean preoperative LDTA was 76.9° (range 68.5°-83.5°). During follow-up, the implant was removed in 12 extremities and the physis had closed in 18 extremities. The mean LDTA at the time of implant removal or at closure of the physis was 83.6° (range 76.5°-90.0°). Mean correction of LDTA was 6.9° after a mean follow-up period of 22 (range 3-43) months. During follow-up, no changes in the Malhotra classification were found in any of the patients. Correction of the valgus deformity of the ankle was significantly correlated (r = -0.506) (p = 0.004) with age in all patients.
  
  
  CONCLUSIONS
  Temporary medial hemiepiphyseodesis of the distal tibia seems to be an effective strategy for correcting ankle valgus in children with MHE. Timing of the intervention is, however, of importance. Hemiepiphyseodesis alone has no effect on the Malhotra classification.
  
  
  METHODS
  IV, retrospective review.
authors.affiliation: Department of Orthopaedic Surgery, Onze Lieve Vrouwe Gasthuis, P.O. Box 95500, 1090 HM, Amsterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: van Oosterbos
authors.affiliation: Department of Orthopaedic Surgery, Onze Lieve Vrouwe Gasthuis, P.O. Box 95500, 1090 HM, Amsterdam, The Netherlands.
authors.forename: A L
authors.initials: AL
authors.lastname: van der Zwan
authors.affiliation: Department of Radiology, Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands.
authors.forename: H J
authors.initials: HJ
authors.lastname: van der Woude
authors.affiliation: Department of Orthopaedic Surgery, Onze Lieve Vrouwe Gasthuis, P.O. Box 95500, 1090 HM, Amsterdam, The Netherlands. s.j.ham@olvg.nl.
authors.forename: S J
authors.initials: SJ
authors.lastname: Ham
keywords: Ankle vargus; Eight-plate system; Multiple hereditary exostoses; Pediatric patient; Temporary hemiepiphyseodesis