Traumatic brain injury (TBI) is the neurological disorder with the highest incidence and prevalence, and poses a huge public health burden for the whole society. An in-depth study of the biomechanics of TBI can help to improve the effectiveness of head protection, develop rapid assessment techniques and take timely interventions, thus reducing the risk of injury deterioration. As a numerical analysis tool, the finite element head model (FEHM) is able to simulate the dynamic response of the head during impact, including the spatial and temporal distribution of stress-strain in brain tissues, and the change of intracranial pressure, which provides an important basis for understanding the mechanical mechanism of TBI. This paper summarizes in detail the current status and development of mainstream finite element models of the human head at home and abroad, traces the development of the models, summarises the characteristics of the models and introduces the research progress of TBI mechanisms based on finite element models. The summary and sorting out of related research will be helpful for the development of new FEHMs and provide theoretical guidance and technical support for the risk assessment of traumatic brain injury and the design of protective equipment.

Lubrication deficiency in articular cartilage (AC) triggers irreversible and progressive degradation of AC, termed osteoarthritis (OA). Bio-lubrication-based strategies have been proposed as effective ways to restore temporary cartilage lubrication for OA postponement or even OA healing. The design of lubricants has inspired an exploration of the reasons behind the low friction in cartilage and the components responsible for the lubrication function in cartilage. Recently, lipids, as emerging lubrication components in AC, have been extensively studied and confirmed to play essential roles in maintaining cartilage lubrication. This review brings forward the main challenges of establishing a satisfactory functional articular cartilage biomaterial with sufficient lubrication from the perspectives of the complexity of physiology and microenvironment of osteochondral tissue. Next, we comprehensively discuss lubrication models of AC, including the lubrication mechanism of AC, OA associated with lipids, lipid lubrication mechanism and application, and the synergistic effects of phospholipids in lubrication. In particular, we highlight the advantages and application of lipids and their derivatives in lubrication. Finally, we analyze the future prospects of lipid-based biomaterials to achieve the perfect treatment of OA. This comprehensive and instructive review can provide deep insights into our current understanding of lipids and lubrication-related diseases.