[Special surgical anatomy and pathology of the 6th extensor compartment of the wrist and reconstruction of extensor carpi ulnas dislocations].

The article describes the special surgical anatomy of the extensor carpi ulnaris tendon (ECU) and the sixth extensor compartment, including the most common pathological conditions. The sixth extensor compartment is only loosely covered and not connected by the extensor retinaculum. The ECU has its own retinaculum at the ulnar head, for which the Latin name "retinaculum privatum" (English: subsheath) is proposed. Dislocation of the extensor tendon (ECU), first described by Schlesinger in 1907, can be treated using various techniques for reconstructing the retinaculum privatum (from the extensor retinaculum, transosseous with a free tendon graft, or using fibers from the Linea jugata).1​ Tendovaginosis of the extensor compartment was first surgically treated by Stein in 1927; the first detailed description was provided by Pfeiffer in 1969 in Volume 1 of this journal.2​, 3​ The sixth extensor compartment is frequently affected in rheumatic diseases. In these cases, significant structural damage is found in the ECU tendon and tendon sheath due to aggressive inflammatory synovitis and instability of the ulnar head (caput ulnae syndrome).