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Podiatry Coding & Billing Alert

Surgical Coding:

Keep Your Os Trigonum Excision Coding Straight for Maximum Benefit

Published on Sun Dec 02, 2012

Hint: Look for your podiatrist's note of a posterior tibial impingement.

If you can narrow your coding options by immediately recognizing an os trigonum procedure, then you're in for fewer headaches. All you have to do is be on the lookout for the podiatrist's note of a posterior tibial impingement.

Our expert advice will show you how to turn this coding challenge into a success.

Make Sure Dx Code Matches Clinical Findings

Your first real challenge with an os excision procedure involves choosing the right ICD-9 code. Why? Because no specific diagnosis code is intended for os trigonum syndrome.

Usually, you'd choose between 726.70 (Enthesopathy of ankle and tarsus) or 726.71 (Achilles bursitis or tendonitis). "I would use the ICD-9 code for accessory bone of the foot, which is 755.67 (Congenital anomalies of foot not elsewhere classified)," suggests Arnold Beresh, DPM, CPC, podiatrist of Peninsula Foot and Ankle Specialists PLC in Hampton, Va.

Your other options include the more non-specific diagnoses -- usually secondary findings -- 729.5 (Pain in limb), 719.57 (Stiffness of joint, not elsewhere classified; ankle and foot), 755.67 (Congenital anomalies of foot, not elsewhere classified), 959.7 (Injury; knee, leg, ankle and foot), 726.72 (Tibialis tendonitis), 727.68 (Nontraumatic rupture of other tendons of foot and ankle), 727.81 (Contracture of tendon [sheath]), and 727.89 (Other disorders of synovium, tendon and bursa; other). Whichever of these codes you have in mind, the key word that will define your selection is "match." Make sure the ICD-9 code you use matches the clinical findings, signs, and/or symptoms.

What it is: Os trigonum is a small bone that lies behind the ankle joint that exists when one area of bone does not fuse with the rest of the talus (ankle bone) during growth. It is considered the second most common accessory bone of the foot. Symptomatic os trigonum usually requires treatment, especially when the pain arises from an ankle injury makes it difficult to discern between os trigonum and a fracture of the posterolateral process of the talus (Stieda's process). Podiatrists might refer to this condition as os trigonum syndrome, posterior ankle impingement (PAI) syndrome, or posterior tibiotalar impingement syndrome (PTTIS).

Surgical Excision Is Not the Only Option

At times, conservative therapy will solve the problem. This includes immobilization, activity modification, athletic taping to prevent end range of plantar flexion, and possible steroid injection. Only when conservative treatment methods do not help the condition your podiatrist would opt to excise the small bone.

How-to: A podiatrist makes an incision behind the ankle, identifies the os trigonum,and dissects it free of its surrounding soft-tissue attachment. For this procedure, you have 28120 (Partial excision [craterization, saucerization, sequestrectomy, or diaphysectomy] bone [e.g., osteomyelitis or bossing]; talus or calcaneus) as an option.

Catch: CPT® has no code for removing an accessory bone, so your payer may give you a hard time approving 28120, especially if the podiatrist isn't dealing with osteomyelitis or other diseased bone conditions. In this case, you can report 28899 (Unlisted procedure, foot or toes). Make sure you arm your report with good documentation explaining an excision of an accessory foot bone.

If the podiatrist reconstructs the patient's tendon, you would code 28238 (Reconstruction [advancement], posterior tibial tendon with excision of accessory tarsal navicular bone [e.g., Kidner type procedure]).

Remember, payers consider 28238 a greater component of the following codes:

  • 27690 -- Transfer or transplant of single tendon (with muscle redirection or rerouting); superficial (e.g., anterior tibial extensors into midfoot)
  • 27691 -- ... deep (e.g., anterior tibial or posterior tibial through interosseous space, flexor digitorum longus, flexor hallucis longus, or peroneal tendon to midfoot or hindfoot)
  • 28262 -- Capsulotomy, midfoot; extensive, including posterior talotibial capsulotomy and tendon(s) lengthening (e.g., resistant clubfoot deformity)
  • 28730 -- Arthrodesis, midtarsal or tarsometatarsal, multiple or transverse
  • 28737 --  Arthrodesis, with tendon lengthening and advancement, midtarsal, tarsal navicular-cuneiform (e.g., Miller type procedure).

That means you cannot report 28238 and get paid separately for it if the podiatrist did any of these five procedures.

Learn More From This Example

How would you report the following scenario involving the removal of os trigonum in this clinical note? Patient has a subtalar joint (STJ) cyst located on the posterior facet. In addition she has os trigonum syndrome due to a severe ankle injury. The podiatry surgeon repairs the STJ cyst, and removes the os trigonum.

Code it: To report the procedure, you would bill two codes in your claim: 28100 (Excision or curettage bone cyst, or benign tumor, talus or calcaneus), and 28120. Don't forget your ICD-9 code for os trigonum, which should support 28120, and which you should base on medical findings and symptoms. In addition, you should report 213.8 (Benign neoplasm of short bones of lower limb) in support of 28100.

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