Winging of the scapula: the underlying biomechanics and an orthotic solution

Abstract

Winging of the scapula occurring in muscular disorders (muscular dystrophy and spinal muscular atrophy) or nerve injury has been investigated, resulting in a thorough understanding and presentation of the underlying biomechanics causing this occurrence. This includes a biomechanical explanation of the characteristic prominence of the medial border of the scapula upon attempted elevation, together with the biomechanical reasons for the rotation of the scapula in a direction contrary to the normal scapulohumeral rhythm. Based on these findings, a non-invasive alternative to the surgical technique for scapular stabilization has been devised, using an inflatable orthosis, placed between the scapula and an external restraint (such as a spinal jacket). The device has been tested on one subject using a 3SPACE Isotrak electromagnetic source and sensor system, and gave encouraging results. Elevation increased by up to 35 degrees (37 per cent), and functional improvement in the use of the hand around the head and face has been achieved. The technique needs no aftercare or physiotherapy and is therefore both economical and functionally effective.