Q. What code should I use for an amputation of the leg through the knee joint? I can find codes for below the knee amputation and above the knee amputation, but not a specific code for an amputation through the joint. Is this is an unlisted service?
A. You can code CPT 27598 (disarticulation at knee) for an amputation of the leg through the knee joint itself. This code may not look correct on the surface because the word amputation is not included in the code descriptor. Also, if you try to look up the word “amputation” in most coding software, you may not find the code. But a little bit of research will help us arrive at this code.
The first key is understanding what the term “disarticulation” means. Per Merriam Webster, a disarticulation is the separation or amputation of a body part at a joint (https://www.merriam-webster.com/medical/disarticulation). Based on this definition, a disarticulation is a synonym for an amputation.
Another helpful resource to better understand the term disarticulation is found in the lay description of CPT 27598 in the Coder’s Desk Reference. The description starts with “to remove the leg at the knee joint….” The description goes on to explain dividing various connective tissues like ligaments and then concludes with “once all connective tissue has been divided, the lower leg is removed.” This explanation of the procedure represented by CPT 27598 also makes it clear that the goal of a disarticulation procedure is removal of the leg at the level of the knee joint (aka an amputation through the joint).
Finally, if you have a paper CPT manual, a good old fashioned index search will help you out. If you start in the index and look up amputation, leg lower, CPT 27598 is one of the options you can select. This index entry further demonstrates that CPT views the term amputation and disarticulation synonymously. If you are using coding software, you can usually go to the electronic index of your CPT manual and start your search there in a process that I call “putting your software into book format.” That type of search will get you to the same options you have in a paper CPT manual. However, if you use the quick search toolbars available in most software which function more like a Google search where you only see results that include your search term “amputation,” you won’t find this particular code.
This surgical coding example highlights the importance of good research skills and taking advantage of all resources available to you when you don’t see the code you are looking for right away. A little extra digging is always worth the effort in coding!
