Intrasheath Tendon Subluxation Beyond the Ankle: The First Case Series in the Hand.

Peroneal tendon intrasheath subluxation is a well-established phenomenon in musculoskeletal ultrasound. However, until now, intrasheath tendon subluxation has not been described in the hand. This unique case series presents the first three reported cases of intrasheath tendon subluxation in the hand. We discuss the anatomy of the flexor and extensor tendons, highlight dynamic sonographic findings, and propose possible mechanisms for this entity. Outside of the ankle, intrasheath subluxation is an uncommon finding, infrequently considered, and easily overlooked, particularly without the use of dynamic ultrasound. Knowledge of this entity and its sonographic features is crucial for its accurate diagnosis.