HSS Ultrasound of the Month Case #107

Clinical History 75 year old female with numbness of the plantar aspect of the foot after recent ankle replacement.

Ultrasound of the Month – Case 107

1

Ultrasound of the Month – Case 107

2

Ultrasound images discussion Ultrasound images short axis (A~E) and long axis (F) to the tibial nerve (arrows) with the location of (A) through (E) indicated by dotted lines in (F) show a transected tibial nerve (arrows) within the tarsal tunnel. The nerve has normal fascicular architecture in (A) and (E) but is thickened with loss of normal fascicular architecture reflecting stump neuromas in (B) and (D) and is absent at the site of transection in (C).

Ultrasound of the Month – Case 107

3

Diagnosis: Iatrogenic Transection of the Tibial Nerve in The Tarsal Tunnel

Discussion Injury to the structures of the tarsal tunnel, including that of the tibial nerve, can occur during ankle replacement.

The tibial nerve as well as its main branches, the medial and lateral plantar nerves, can be well visualized under ultrasound.

Transection of the nerve results in disruption of all of the individual fascicles of the nerve as well as the perineurium and the epineurium.

Transection may require treatment by nerve grafting.

Other abnormalities of the tibial nerve that may be appreciated on ultrasound include incomplete laceration, neuroma formation, and extrinsic compression by pathology such as cysts, soft tissue masses, or scar tissue.

Ultrasound of the Month – Case 107

4