LAUSR

BACKGROUND We postulated that residual distal radioulnar joint (DRUJ) instability after distal diaphyseal or metaphyseal fracture in the radius or ulna may occur due to malaligned or malunited bony structures as well as primary or secondary soft issue stabiliser. Here, we report the outcomes of corrective osteotomy in a retrospective study. METHODS Patients undergoing the osteotomy for DRUJ instability between March 2000 and February 2018 were included in the study. Thirteen patients were evaluated. The initial injury occurred at a mean age of 12.3 years and corrective osteotomy was performed at a mean age of 20.8 years. The mean follow-up period was 33.1 months. The male to female ratio was 8:5 and the corrected radius/ulna ratio was 11:2. DRUJ instability was diagnosed clinically and radiologically based on the stress/clunk test and the distance between the cortex of the radius, and the radioulnar ratio. All osteotomies in the radius and ulna were of the open wedge type and were performed using plates/screws. RESULTS The radioulnar ratio was significantly higher than the normal ratio (p < 0.001). All osteotomies healed well without any serious complications. The preoperative distance between the cortex of the radius and ulna was significantly decreased at the final follow-up, from 4.74 ± 0.82 to 1.16 ± 0.46 mm (p < 0.001). Positive findings of two instability tests were all converted to negative. The ranges of motion of the flexion-extension and pronation-supination arcs were significantly improved. Finally, preoperative VAS pain and DASH scores improved to 0.23 ± 0.44 and 3.92 ± 1.84, respectively (p < 0.001). CONCLUSIONS Malunited radius or ulna plays a role in DRUJ instability, affecting the bony geometry in terms of the relationship between the sigmoid notch and ulnar head. Treatment of malunion by corrective osteotomy represents a useful option for resolving instability. LEVEL OF EVIDENCE Level IV, Retrospective therapeutic study.