(i) Basics of orthopaedic biomechanics

An outline of the basic principles of orthopaedic biomechanics is presented. Joint moments, muscle moment arms, in vivo forces, contact stresses and joint stability are all discussed with recent clinical examples to demonstrate their importance. These clinical examples focus on the hip and the knee and include: the effects of femoral offset and reducing the abductor moment arm on hip arthroplasty, how the knee adduction moment causes an asymmetric load distribution between the condyles, the magnitude of in vivo forces and their implications for wear, the consequences of meniscectomy on cartilage contact stresses, extreme contact stresses caused by edge loading in hip replacements, the effect of femoral head size and capsular repair in total hip replacement stability, knee medial rotation and the role of the anterior cruciate ligament in joint stability.