Isolated ulna dislocation in distal radioulnar joint without fracture

Isolated volar ulna dislocation in distal radioulnar joint (DRUJ without fracture is rare pathology. There is no research regarding this dislocation, only other case reports. In about 50% cases is misdiagnosed or diagnosed in late phase. 47 years young woman got trauma at home. Mechanisms of trauma was hand hipersupination with fixed ulna. She was misdiagnosed twice in 2-day interval in two different trauma specialized hospital emergency departments. Correct diagnosis was made in ambulatory department. Patient was complaining about pain in wrist. Her hand flexion and extension were almost full range but was fully blocked pronation and supination, ulnar and radial deviation. By physical examination there were no palpable styloid of ulna. CT scan showed full ulna dislocation to volar side without any fracture. Surgery was 3 weeks after trauma. In OR under plexus anesthesia closed reduction with hiperpronation of hand. Reposition was successful and went without problem, under C-arm anatomy of DRUJ was restored. As reposition went easy, decision was made to stay with closed reduction and osteosynthesis with percutaneous K wire pinning proximal to DRUJ. Postoperative CT scan showed ulna subluxation in DRUJ. Open DRUJ revision was done after 4 days. In open revision dorsal radioulnar Līgament was torn and TFCC was dislocated in DRUJ and blocked full reposition of ulna. TFCC was sutured back to fovea ulna. Percutaneous pinning with K wire proximal to DRUJ for 3 weeks was also made for extra stability. 6 weeks after operation patient has full range flexion and extension. After pin removal slightly reduced passive protantion/supination. This case report shows importance of soft tissues and TFCC in DRUJ. Malreduction and soft tissue interposition after close reduction could be more often in such trauma . MRI should be done if there is suspicion of soft tissue trauma rather then fracture.