Posteroanterior motion test of a lumbar vertebra: accuracy of perception

The aim of this study was to investigate the accuracy of perception of forces applied to and displacement produced in an electromechanical one vertebral spinal model, among inexperienced and experienced physical, therapists performing posteroanterior pressure on a lumbar vertebra, before and after a training session.

Ten relatively inexperienced physical therapists and ten experienced manual therapists participated. An electromechanical single level spinal model was used for applying oscillatory posteroanterior pressure and measuring the forces on and displacement of the vertebra. A digital oscilloscope was used to give direct feedback to the therapists while performing mobilization to discern the magnitude of these two variables.

The inexperienced group estimated the displacement accurately but the experienced group was significantly inaccurate (p<0.02), and both groups were inaccurate in estimating the force (p<0.001), before training. Following training, the inexperienced group maintained their accuracy on displacement and the experienced group improved their accuracy significantly (p<0.001). Both groups approached significance in improving their accuracy of force estimation.

An electromechanical spinal model can be used as training tool along with an oscilloscope. Longer training may be needed for the force than the displacement for accurate perception.