Orthopedic Coding Alert

Question: What is trephination, and how should I code for an arthroscopic knee trephination?

Georgia Subscriber

Answer: During trephination, your orthopedist uses a surgical instrument, called a trephine, to make an opening in a bone. Usually, we associate this with procedures that involve creating a hole in the cranium or facial bones to provide access to the brain or sinuses (for example, 31070, Sinusotomy frontal; external, simple [trephine operation]). But your orthopedist can use this procedure on other bones as well. When it's applied to bones other than those of the face or cranium, most orthopedic surgeons refer to this procedure as "microfracture."

With that in mind, you have to determine where the surgeon is applying the trephine in the knee to select the appropriate code. If he is trephining the meniscus, you must use the unlisted-procedure code (29999, Unlisted procedure, arthroscopy).

On the other hand, if he's trephining the bone at the insertion point of the anterior cruciate ligament to stimulate a healing process, your best code choice is 29879 (Arthroscopy, knee, surgical; abrasion arthroplasty [includes chondroplasty where necessary] or multiple drilling or microfracture) because it includes drilling.

-- Reader Questions were reviewed by Heidi Stout, CPC, CCS-P, director of orthopedic coding services at The Coding Network LLC; and Bill Mallon, MD, orthopedic surgeon and medical director at Triangle Orthopaedic Associates in Durham, N.C.