Presence of anomalous flexor carpi radialis brevis (FCRB) in Madelung's deformity.

An anomalous flexor carpi radialis brevis (FCRB) muscle was present in four of nine patients undergoing surgery for Madelung's deformity. This disproportionately frequent finding suggests an embryologic dysgenesis of forearm formation rather than a developmental tethering of Vicker's ligament. Level of evidence: IV (case series).