[Treatment of fresh and old ruptures of the extensor tendons (author's transl)].

Knowledge of topographical anatomy and physiological interplay of several structures is considered essential for regaining the normal function of the extensor apparatus of the finger after an acute or an old injury. For better comprehension of the extensor apparatus and because of its anatomical and functional complexity, two types of structural systems are described, namely, the tendinous and the retinacular system. Aetiological aspects and the pathophysiological mechanisms of deformities such as the "swan-neck deformity, boutonnière deformity and mallet finger" are also described and possibilities of surgical treatment are discussed. Rare injuries such as laceration of the extensor pollicis longus tendon or laceration of the metacarpophalangeal extensor hood with a consecutive radial or ulnar shift of the long extensor tendon are also described and mentioned with possible surgical treatment methods.