Research status for knee joint secondary kinematics

Osteoarthritis are usual disease in middle aged and elderly people. High tibial osteotomy is a common method which performed to treat medial compartment osteoarthritis in varus knees. Unicondylar knee arthroplasty is an established treatment option for symptomatic osteoarthritis isolated to one compartment, and received remarkably effect. Total knee arthroplasty is the standard treatment of serious knee disease. The knee kinematics have changed after the knee was diseased, and the kinematics after surgery are different from the natural joint. The flexion-extension rotation, anterior-posterior translation and interior-exterior rotation are most important kinematics of tibia-femur joint. The anterior-posterior translation and interior-exterior rotation, which as the secondary kinematics, even are paradoxical after total knee arthroplasty. Secondary kinematics studies played an important role in prosthesis design and postoperative functional assessment. Measurement and description methods of knee joint secondary kinematics were reviewed in this article. The factors influencing secondary kinematics were investigated for natural knee joint, osteoarthritis knee joint and knee joint after total knee replacement separately, and the influence of total knee replacement design was emphasized. At last, the impact of knee secondary kinematics to biomechanics, friction and wear were also introduced. After comparison of multi-research results, the measurement precision was found to need further improvement due to the restrict of measuring technology and description methods. Many factors influence knee secondary kinematics, including activities, measurement environment and individual difference. The anterior-posterior translation was found complex after total knee replacement, and the prosthesis design played an important role. Posterior cruciate ligament-retaining knee replacement lead forward slide of the femoral component during flexion, which paradoxical from natural knee. The anatomical design prosthesis were hopeful to realize more natural kinematics. The component malalignment and soft tissue balance during surgey also have significant role in knee secondary kinematics. The knee secondary kinematics study is of great significance to biomechanics and wear.