Anatomy and biomechanics of the distal radioulnar joint

The functionality of the upper extremity is decisively based on rotation of the forearm. The rotation depends on the extent of motion of the distal radioulnar joint. Rotation enables complete and focused usability of the hand in order to cope with daily activities. The configuration of the distal radioulnar joint has developed over millions of years of evolution. The triangular fibrocartilage complex is the crucial stabiliser of the latter joint since osseous structures are limited. The palmar and dorsal radioulnar ligaments belong to this complex. The superficial and deep parts of the latter ligaments insert both centrically in accordance to the axis of rotation and eccentrically. This arrangement guarantees stability of the joint throughout pronosupination. The interosseous membrane is a further relevant stabiliser that guarantees sufficient load transmission from radius to ulna. The distal oblique bundle of the interosseous membrane is outstanding in this context. The pronator quadratus muscle is the relevant dynamic stabiliser of the distal radioulnar joint. Contraction of the muscle prevents diastasis of the joint. The deep head of the muscle is always activated during pronosupination.