Osteopathic decapitation: Why do we consider the head differently from the rest of the body? New perspectives for an evidence-informed osteopathic approach to the head

The osteopathic management of the head was initially founded on a biomechanical model which has since proved to be highly controversial. The current call for the evidence-informed practice of osteopathy, and the level of critical reasoning we expect from our students, are no longer compatible with Sutherland's ideas on cranial osteopathy.Meanwhile, an interesting field has developed called tissue mechanics. This may provide osteopaths with useful evidence to develop a treatment model of the head that fits better with current knowledge. Biomechanics is not limited to kinematics to the human body. It includes tissue mechanics that aims to describe the way living tissues distort under different types of loading. It has been extensively applied to understand the role and development of cranial sutures and the distribution of stresses and strains over the skull.Even though it is among the hardest materials in the body, bone distorts during normal function and more obviously during trauma. Bone tissues undergo stresses and strains when loaded, like any other material, and cranial bones are no exception to this rule.In this article we review the mechanical properties of the cranial bones and sutures and highlight the fact that the muscles are the main cause of cranial bone deflections. Muscle contraction is now recognized to be one of the principal causes of bone loading and this is true for the head: apart from in the case of traumatic events, a large amount of research into the mechanical properties of cranial bones and sutures confirms that muscle contraction is the main cause of skull deflection.