Anesthesia Coding Alert

Question: A new coder in our department told us that her previous practice treated patients with tarsal tunnel syndrome (TTS). I didn’t ask her at the time, but I am wondering now: What is TTS, is it similar to carpal tunnel syndrome (CTS), and are there ICD-10 codes for the condition?

Massachusetts Subscriber

Answer: There’s a lot to unpack here, but let’s start with an affirmation of TTS. According to aapmr.org, TTS is “entrapment of the tibial nerve or branches of the nerve within or distal to the tarsal tunnel of the medial ankle. This is an extremely rare diagnosis and can reasonably be thought of as a pain syndrome.” Since TTS is so rare, it’s likely that some PM clinics have never seen a patient with the condition.

CTS comparison:  TTS is not just CTS of the lower extremities, though the conditions share some symptoms. One major way that TTS and CTS differ is that CTS is often the result of repetitive stress. According to aapmr.com, however, “compared with carpal tunnel syndrome, chronicrepetitive injury is believed to be a rare etiology” for TTS.

Some common TTS etiologies include “acute trauma, such as sprains, strains, or fractures. Other causes include mass lesions from venous varicosities, cysts, lipomas, tendon sheath ganglia, bony exostoses, or tumors. Inflammatory arthropathies may also cause tarsal tunnel syndrome,” reports aapmr.com.

Choose your diagnosis: If your PM specialist treats a patient for TTS, you’ll assign one of the following ICD-10 codes, depending on patient specifics:

• G57.50 — Tarsal tunnel syndrome, unspecified lower limb
• G57.51 — … right lower limb
• G57.52 — … left lower limb
• G57.53 — … bilateral lower limbs.