How to Determine if OS Site is Primary or Secondary?

Q: “Can we discuss coding osteoarthritis? I often see it diagnosed as osteoarthritis with a specified site but not if it is primary or secondary.”

A: This one is pretty simple. A primary osteoarthritis is considered wear and tear, and is the most frequently diagnosed by healthcare providers. Secondary osteoarthritis has a specific cause, such as an injury or resulting from obesity, genetics, inactivity or other diseases. Then, there’s also post-traumatic osteoarthritis, which is the wearing out of a joint that has had any kind of physical injury.

What exactly is osteoarthritis? It’s the breakdown of cartilage causing the bones to react to those areas, often developing bone spurs or growths. The joints may become inflamed and swollen. When the bones touch without the protective cartilage, pain and stiffness result. When we’re coding for osteoarthritis, we have a site and laterality designations.

VIDEO: How to Determine if OS Site is Primary or Secondary

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I find that doctors such as orthopedics, podiatrist, chiropractors, they tend to be much more specific with laterality and the site; however, primary care has a tendency to just write osteoarthritis.

Primary osteoarthritis typically develops around 55-60 and it is associated with aging. The longer you use your joints, the more likely you are to get this type of arthritis.

Secondary osteoarthritis is either from an injury, if you fracture a bone playing sports or are in a motor vehicle accident, you will most likely develop osteoarthritis in that joint. Obesity – the extra weight bears down on the joints every day causing the joint to wear away faster. Inactivity – if you are inactive, you have weaker muscles and tendons that surround the joint. Strong muscles keep the joints properly aligned.

Genetics – you may carry genes that put you at risk. Then, inflammation from other diseases – rheumatoid arthritis can increase your risk of getting osteoarthritis later in life.

How to Determine if OS Site is Primary or Secondary?The next page is a picture of osteoarthritis of the hip. You can actually look at the two and you can see the difference between the normal side of the hip and the one with the osteoarthritis. The code range for osteoarthritis is M15 to M19. I just happened to pick the M16 – osteoarthritis of the hip, and the laterality is identified within the category. This is not even all of them, I just picked these particular codes just to show you how they’re labeled.

M16.0 will be bilateral primary osteoarthritis of the hip, and then .10 is the unilateral primary, unspecified hip; .11 is primary unilateral, right hip; .12 is unilateral primary, left hip; .4 is unilateral post-traumatic, unspecified hip; and .7 is secondary arthritis of hip, other unilateral. There are a lot more in the M16 as well as the other codes, but I just wanted to point out those key words: primary, post-traumatic, and secondary.

Now, what you need to look for and one of the things you learn with ICD-10 is that you’re not only learning the coding, but you’re also learning the pathophysiology. First, when you’re looking at the documentation, before you query the physician, wanted to see if it’s in the documentation, is the hip, the knee, the carpometacarpal joint? Does it indicate in the documentation, even if the doctor just chose osteoarthritis, if it’s left, right or bilateral?

If the physician does not provide information regarding being primary, secondary, or
post-traumatic, you may reference that in the note. He may indicate age, or wear and tear. He may indicate that the patient is obese and gives a body mass index and so forth. You may be able to determine from the documentation if it’s a primary or secondary. Does the note indicate stiffness or joint enlargement? Is there lab work indicating a white blood count or x-rays taken? Things like that.

If you cannot figure it out based on this type of information, then you have to query the physician. I can tell you firsthand that these unspecified codes are not going well with the insurance companies so you really want to be specific.

How_to_Determine_if_OS_Site_is_Primary_or_Secondary_-_YouTube-2In the last slide it will show the synovial joint, and again, it just shows you what a healthy joint looks like and then when you look at the osteoarthritis illustration, you can look at where the cartilage is not there and the whole joint cavity with synovial fluid is just very thin, so the bones rubbing together and that’s basically what it is.

So, the primary is wear and tear, secondary is due to a lot of other factors. If you can’t determine based on documentation, I would query the doctor unless you want to use unspecified. They’re there, but as a biller, I don’t recommend it. It’s a pain to have to appeal a claim and they’re not liking the unspecified diagnosis codes in most cases.

Laureen: That was one of the questions in the chat. If they just say osteoarthritis, do you code it as unspecified? Your advice is to query the physician, but if you can’t do that then you have to go with unspecified, right?

JoAnne: Right. Again, it really depends on the insurance company, but I can tell you 8 out of 10 times any unspecified codes that the billers that I know used end up having to appeal the claim, that insurances don’t like it, particularly when it comes to the bones. Just saying. That’s pretty much it.

Laureen: Thanks JoAnne.

JoAnne: You’re welcome.

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10 thoughts on “How to Determine if OS Site is Primary or Secondary?”

  1. Great information. I enjoyed reading the discussion. Orthopedic issues in medical coding is somewhat bit tricky too, and this information is a great help.

  2. Great information… THANK YOU! I am still a little confused in regard to “secondary” versus “post-traumatic,” as the slide indicates that osteoarthritis as a result of an injury would be secondary rather than post-traumatic. Again, great information!

  3. Very good information. I am still a bit unclear as to how to differentiate between secondary (when due to an injury) and post-traumatic, if not specified by the provider. As well, I have issues when a provider gives the osteoarthritis diagnosis with the site (ie left knee osteoarthritis) the encoder defaults to “primary” however I am unaware of any guideline that directs the coder to default to primary in order to specify site. Thanks again for the information!

  4. Primary osteoarthritis is more about wear and tear and is associated with aging.
    Secondary osteoarthritis has a specific “cause”. Let’s say you fracture a bone playing football or broke a leg in an automobile accident. Inactivity and obesity are secondary reasons as well. Osteoarthritis is also something that occurs if a patient has another disease such as rheumatoid arthritis.
    I have typically seen primary OS diagnosed in primary care offices and secondary OS in specialists’ offices because they are dealing more specifically with a problem.
    In truth, without any indication in the progress report/documentation, I would lean towards Primary OS just like Encoder suggests.


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