[Biomechanics of arthrodesis of the major joints of the extremities].

Insufficient movement after an arthrodesis must be compensated for by other joints. Arm movements with an ankylotic shoulder joint can be executed by rotation and tilting of the scapula. The trapezius muscle plays an important role in these movements. Arthrodesis of the hip joint requires an extended range of movement in the intact contralateral joint and sufficient mobility of the lumbar spine. Moreover, every ankylotic joint is stressed by bending because compensation of the torque due to the weight of the corresponding part of the body by the balancing muscles is no longer necessary. The architecture of the spongy bone is adapted to that bending stress. Characteristic examples are anatomic specimens of ankylotic hip and knee joints.