Orthopaedic biomechanics means to apply biomechanics methods to resolve clinical problems in orthopaedics, especially when mechanical principles are used, lots of problems unsolved could be ravel out. For instance, the design and clinical application of artificial joint replacement with the help of biomechanics can ease the patients' pain suffering from degenerative arthritis. 11 papers related with orthopaedics biomechanics published in this special issue involve in the study on tissue engineering, sports medicine, spine and artificial joints from both the clinical application and basic research with the methods of material testing machines and finite element analysis by computer. These articles could help readers understand how mechanics is used in orthopaedic research and hope to encourage them to find more issues suitable to use orthopaedics biomechanics to research in the clinic practice.