Ulnar shortening to unload the ulnocarpal ligamentous complex. Clinically relevant ulnar impaction syndrome, be it congenital or posttraumatic. Concomitant pronounced malunion of the radius. Osteoarthritis of the distal radioulnar joint. Ulnopalmar approach. Oblique osteotomy of the ulna in its distal third. Removal of a bony wafer of predetermined thickness. Internal fixation with a 7-hole LD-DC plate or special plate and lag screw. 29 patients (14 men, 15 women, average age 42 years) underwent an ulnar shortening osteotomy for a therapyresistant ulnar impaction syndrome. Follow-up after an average of 25(7–37) months. Average amount of shortening 4.5 (1.5–13) mm. 72% reduction of pain as determined with a visual analog scale. The range of motion was improved by 7% in extension/flexion, by 8% in abduction/adduction, and by 11% in pronation/supination. Grip strength measured with a vigorimeter (balloon size 5) increased by 12%. Complications: three malunions, effectively treated by revision of internal fixation.