[The Armstrong procedure in scoliosis surgery. Clinical, biomechanical and tridimensional study].

The Armstrong procedure combines the use of a conventional Harrington rod in the concavity of a curve, together with a distracting force on the convex side, this force being applied one vertebra lower. Workers have used this procedure in 35 cases. It is concluded that there are three advantages: A better horizontal disposition of the lower vertebra. Greatly diminished stress on the two rods shown by a biomechanical study. Derotation is more easily obtained and the spine is better balanced as a whole, as shown by a three-dimensional study comparing this method and conventional Harrington rodding.