Sudden Release of a Fixed Contracture as a Clue to Occult Humeral Fracture in a Neonate With Arthrogryposis Multiplex Congenita.

A neonate with multiple congenital contractures consistent with arthrogryposis multiplex congenita was found to have an initially clinically occult humeral shaft fracture immediately after axillary cleansing. The first abnormal sign was the sudden release of a previously fixed upper-limb posture, which initially resembled improvement in contracture, before swelling, erythema, or deformity became apparent. Radiography confirmed a spiral fracture of the midshaft of the left humerus, which healed with conservative treatment. This case highlights that an abrupt apparent improvement in a fixed contracture after handling should prompt consideration of occult long-bone fracture and targeted radiographic assessment. Careful support of the entire long bone and avoidance of rotational force across stiff joints may help reduce the risk of a handling-related injury during routine neonatal care.