Dynamic lower extremity alignment in children with achondroplasia
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Published on: February 27, 2018
Muharrem Inan1, Mihir Thacker, Chris Church
1Orthopeadic Department, Inonu University Medical Faculty, Malatya, Turkey.
Abstract:
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.
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