Dynamic lower extremity alignment in children with achondroplasia

J Pediatr Orthop. 2006 Jul-Aug;26(4):526-9. doi: 10.1097/01.bpo.0000217712.42115.e6.


The purpose of this study is to analyze lower extremity dynamic malalignment during gait using a 3-dimensional kinematics and kinetics in 13 children (3-17 years old) with achondroplasia and to compare measurements of alignment and malrotation between gait, radiographic, and clinical measures. Gait analysis in the coronal plane showed a varus malalignment of the knee (19 +/- 13 degrees) and variable tibial torsion abnormalities (13 [internal] +/- 15.7 degrees). Radiographs also showed knee varus malalignment (16 +/- 9 degrees); however, there was poor correlation with gait analysis measures (P > 0.05). In the sagittal plane, radiographs showed genu recurvatum deformity (23.5 +/- 13.2 degrees), although the sagittal plane knee kinematics were normal. Kinetic analyses of the knee showed high internal knee valgus moments (external varus moments, 0.48 +/- 0.25 N m/kg), which were significantly different from the normal population (P < 0.05). In conclusion, there is a 3-dimensional, complex, dynamic deformity of the lower extremity present in children with achondroplasia. We recommend a very careful assessment of the limb focusing on both the static and dynamic varus deformity and tibial torsion using a combination of radiographic, clinical, and gait analysis.

Publication types

  • Comparative Study

MeSH terms

  • Achondroplasia / diagnostic imaging
  • Achondroplasia / physiopathology*
  • Adolescent
  • Child
  • Child, Preschool
  • Female
  • Follow-Up Studies
  • Gait / physiology*
  • Humans
  • Knee Joint / diagnostic imaging
  • Knee Joint / physiopathology
  • Male
  • Prognosis
  • Radiography
  • Range of Motion, Articular / physiology*
  • Retrospective Studies
  • Severity of Illness Index
  • Tibia / diagnostic imaging