Hyperextension Injury of the Thumb Causing Volar Plate and Sesamoid Displacement: Sonographic Findings

An unusual patient case is provided of combined dislocation of the volar plate and its associated sesamoid at the interphalangeal joint of the thumb. This reportedly occurred following a sudden hyperextension trauma with resultant limitation in joint range of movement. The radiographs that were taken of the thumb were interpreted as normal; however, the magnetic resonance imaging (MRI) findings were initially overlooked. The sonographic examination effectively characterized the injury and was subsequently confirmed upon review of the MRI results and subsequent clinical assessment. Surgery was avoided, as the functional limitation involved only the non-dominant hand and was well tolerated by the patient.