In the second of this series on soft tissue injury, the principles of biomechanics, physiotherapy and imaging are covered. Although injuries vary immensely in severity and according to location, an understanding of key areas helps practitioners to assess and manage injuries from first principles. The “key areas” involved include anatomy, physiology and pathology, subjects which tend to be learned now in less detail than previously.

The ability to assess injuries from first principles is a learning goal, and structured learning combined with supervised clinical teaching should allow all practitioners to develop this expertise. Sufficient volume of clinical caseload is perhaps the rate-limiting factor for many, partly through more sensible rotas, partly because safety in the home, workplace and roads has minimised serious injury, and partly as the gross pathologies of the past tend to be resolved at a much earlier stage.

HUMAN BIOMECHANICAL PRINCIPLES

Human biomechanics is the science that studies how our bodies function as machines, that is, how they cope with all the stresses and strains of life. It explores the reasons for “component failure” or injury. Biomechanics is a huge subject area; this section can only skim the surface. Readers are referred to “The Human Machine”1 for a very thorough review of the subject. Many of the concepts in this section are taken from that book.

The relationship between joints and muscles is precise. Whatever range of movement a joint possesses, it is surrounded by muscles which can achieve this range. All muscles are arranged in opposing pairs, with perfect balance between them. When one muscle contracts, its opposing partner relaxes, yet maintains enough tone to stabilise the joint.

The complexity of dynamic muscle control can easily be demonstrated. If a healthy human being stands on one leg with closed eyes, he/she will stay upright. Clearly it …