Mechanics of spinal joint manipulation in the thoracic and lumbar spine: a theoretical study of posteroanterior force techniques

Posteroanterior (PA) forces applied to the vertebrae are commonly used for the clinical assessment and treatment of vertebral column disorders. Three strategies for applying PA force in the thoracic and lumbar spine regions were studied. The components of the manipulative force which were directed along, and transverse to, the axis of the vertebra were calculated, and also the sagittal plane moment generated about the centre of the vertebra was determined. The three different strategies produced quite different loads on the vertebrae and all three strategies showed substantial variations across vertebral levels in at least one of the load components.