Background: Extra-ocular muscle rupture is uncommon, usually seen after penetrating trauma or surgery. It is a very rare cause of diplopia following blunt orbital trauma.
Methods: A patient who presented with no inferior rectus function after blunt orbital trauma is described.
Results: Computed tomography (CT) scans demonstrated a large orbital floor fracture and suggested that the inferior rectus muscle was ruptured. This was confirmed at operation. Despite anatomical repair, there was no postoperative improvement in ocular motility.
Conclusions: Traumatic rupture of the inferior rectus is rare. Forced duction and force generation testing and CT are important in diagnosing ocular motility defects following orbital trauma.