During the human postnatal developmental process, extensive tissue and morphological changes occur. Many take place in the first few years of life but substantial development for several body regions continues well into young adulthood. Along with overall change in size, these material and structural changes influence the biomechanical response of child such that they respond differently to traumatic load than an adult. Understanding the unique biomechanical response of the child is challenging, as compared to the wealth of biomechanical data on the adult response to trauma, pediatric biomechanical data are relatively sparse. As a result, quantitative scaling relationships based on anatomical and material differences have been historically used to understand the biomechanics of the child. The last decade, however, has seen a tremendous increase in contributions to the biomechanics literature based upon pediatric subjects – volunteers, post-mortem human subjects, and animal models – thus increasing our knowledge of how to design injury mitigation systems to protect the young.

In this chapter, aspects of developmental anatomy and biomechanical knowledge are reviewed to provide context for pediatric human injury prediction. Emphasis is initially placed on the head and brain as this body region represents the most common seriously injured body region for children in virtually all unintentional injury modes. Specifically, head injuries are particularly relevant clinically as the developing brain is difficult to evaluate and treat, and even mild brain injuries in childhood can lead to deficits that remain long after the injury. Discussion follows on the cervical spine and thorax as these body regions are not only important from an injury mitigation standpoint but they govern the kinematics of the head during traumatic loading and therefore play a role in head injury protection. A brief description follows for the other body regions:​ the abdomen and extremities as well as an outline of the scaling theory used by many researchers to scale adult biomechanical data to the child. The biomechanics data contained in this chapter may assist in improving the accuracy of pediatric injury criteria and the biofidelity of child anthropometric test devices (ATD) and human body computer models. Because of space limitations, this chapter does not serve as an inclusive data repository for all pediatric material property and biomechanical response data but rather summarizes the seminal publications in the field and directs the reader to other resources for more detailed data.