Spontaneous Reduction of Radial Head Dislocation by Gradual Ulnar Lengthening in Patients With Ulnar Growth Disturbance.

PURPOSE: Radial head dislocation associated with a relatively short ulna is the most severe deformity of the forearm. Surgical reduction of the radial head is challenging and often yields unpredictable results. This study investigated whether, in pediatric patients, a dislocated radial head could be spontaneously reduced through gradual ulnar lengthening.

METHODS

In this retrospective study, we reviewed patients who underwent ulnar lengthening by distraction osteogenesis from June 2008 to March 2024. Patients with short ulnas accompanied by dislocated radial heads were included. The radial head position after traction and the relationship between the radial head and capitulum were radiologically assessed at the time of external fixator removal and the final follow-up. The patients were divided into two groups according to the radial head position at the cessation of ulnar distraction: group A (at the level of, or proximal to the coronoid process) and group B (distal to the coronoid process).

RESULTS

The study included 20 patients with a mean age of 8.7 years (4.5-14.9 years) at the time of index surgery. The mean ulnar lengthening was 4.3 cm (2.3-6.8 cm). The mean follow-up time was 2.8 years (0.5-10.2 years). There were 8 patients in group A and 12 patients in group B. Radial head reduction was observed in nine patients (all from group B) at the final follow-up. Successful reduction tended to occur when the radial head was positioned distal to the coronoid process after ulnar distraction.

CONCLUSIONS

Spontaneous concentric reduction of the radial head can be achieved through gradual ulna lengthening. The position of the radial head distal to the ulnar coronoid process after traction may be the key to successful reduction.

TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.