A Hidden “Suspender” in Irreducible Isolated Anteromedial Radial Head Dislocations – A Case Report and Review

INTRODUCTION: Isolated anteromedial radial head dislocations are rare and are infrequently associated with hidden musculotendinous sling of superficial brachialis or biceps tendon impeding closed reduction. Failure to identify this impeding tendon can lead an unsuccessful and unstable open reduction surgery. This is the first case of its kind where the delayed presenting patient was treated without resection of the tendon. CASE REPORT: We describe a case of an irreducible neglected isolated anteromedial radial head dislocation in a 7-year-old male child presenting 2 months following injury with features of active heterotrophic ossification (HO). Open surgical exploration 4 months following the injury through the Boyd’s approach revealed a hidden musculotendinous sling of superficial brachialis suspending the radial head anteromedially. Releasing the adhesions and relocation of the tendon allowed spontaneous radiocapitellar joint reduction. The joint congruency was maintained at 18 months and the functional outcome was excellent with a mild flexion-pronation deficit. CONCLUSION: Awareness of the rare impeding biceps/brachialis tendinous sling in cases of isolated anteromedial radial head dislocation can guide the surgeon to order an indicated preoperative magnetic resonance imaging and plan an early open reduction. HO may occur frequently with such an injury considering the severity of the associated soft-tissue injury.