The team of authors presents a case of the patient who suffered an isolated unstable extra-articular distal ulnar fracture, the surgical treatment of which was affected by a postponed management in consequence of inadequate primary treatment. The primary non-operative treatment resulted in a complex malunion ad latus, ad axim and ad peripheriam. The malunion which led to a painful restricted range of motion of the forearm (59%), decreased hand grip strength and significant limitation of activities of daily living was surgically treated by a triplane corrective osteotomy at 11 months after injury. At 12 months after surgery, a complete ulnar bone union was observed, the patient showed no residual wrist pain, the range of motion of the injured forearm reached 97 % of the range of motion of the unaffected forearm (side), and the hand grip strength was 95% of the hand grip strength in contralateral limb. The treatment outcome can be assessed as very good based on the Quick DASH score. Displaced isolated distal ulnar fractures cause a change in the axial position of the distal end of the bone and can be associated with an injury to the stabilizers of the DRUJ. Thus, they can result in a limited range of motion of the forearm due to the impaired DRUJ biomechanics and development of early post-traumatic osteoarthritis of the DRUJ. The non-operative treatment is recommended only for stable and non-displaced fractures as well as fractures in which surgical treatment is contraindicated. Corrective osteotomy of the distal ulna is the method of choice in managing distal ulna malunion as a result of isolated distal ulnar shaft fractures in symptomatic patients. Good functional outcomes may be achieved if the anatomical position of DRUJ is restored. Key words:corrective osteotomy, distal ulnar fracture.

Klinika úrazové chirurgie Masarykova nemocnice v Ústí nad Labem a Univerzita Jana Evangelisty Purkyně v Ústí nad Labem