What to Know About the ICD-10 Code For Impaired Mobility

Treating patients is not easy, and correct ICD-10 coding can be just as difficult—and just as essential to make sure you don’t do extra work. That’s why we’re helping you make sense of some of the more obscure ICD-10 codes and when you should use them in your practice—and when you shouldn’t. In this post, we’re looking at coding for patients with impaired mobility and activities of daily living, including some ICD-10 codes that may be similar, but different. 

How do I use the ICD 10 code for impaired mobility?

For patients experiencing impaired mobility without a specific medical diagnosis, you can use the ICD-10 code for other reduced mobility Z74.09, which is described in this resource as applicable to patients who are chair-ridden or have reduced mobility that is “NOS” (medical speak for not otherwise specified). The ICD-10 code for impaired mobility is relatively new and became reimbursable and effective on October 1, 2023.

What’s the deal with Z codes?

The name of the game in ICD-10 is to code for specificity, and to do that physical therapists (and occupational therapists) need to know the root cause of why a patient may need physical therapy (rehab) services. In ICD-10 coding, the term 'initial encounter' is used to denote the first encounter with a particular medical issue. Aftercare codes (specific to Z codes) help to provide medical billers and other medical professionals a glimpse into the nature of a patient’s dysfunction. Generally, a rehab therapist is going to apply an aftercare Z code when the patient has been adversely affected by a disruptive event—like an injury, an illness, or a surgical procedure.

In physical therapy, the aftercare codes are often applied to patients receiving aftercare for a joint replacement—or other musculoskeletal surgery—but there certainly are instances where a person needs physical therapy due to prolonged bed rest or loss of ability to ambulate resulting in otherwise impaired mobility—hello Z74.09.

Are there any exclusions with Z74.09? 

Yes, there is a Type 2 excludes note for Z74.09, other reduced mobility, and they include Z99.3, wheelchair dependence. 

When should you use ICD-10 codes for abnormalities of gait, difficulty walking, or impaired mobility?

The importance of specificity when using ICD-10 codes for a physical therapy evaluation cannot be understated. If you incorrectly use an ICD-10 code for a patient’s case, such as coding for difficulty in walking instead of a more specific condition, the result could be claim denials, disruptions in patient care, and more.

As we wrote in this ICD-10 FAQ,

“To code for weakness in a specific area, use the appropriate atrophy code (you’ll find many of these codes in the M62.5 code family). Additionally, keep in mind that the coding guidelines encourage you to code first for the underlying cause of the weakness, rather than the weakness itself. If you are able to do that, you can include the atrophy codes as secondary.”

So to help you along the way let’s delve into when a person should have a postural instability, gait disorder diagnosis vs the ICD-10 code for impaired mobility. Suppose the patient being seen for gait and mobility has difficulty with ambulation and is not confined to a chair or other impaired participation in ADLs. In that case, you should use a diagnosis reflective of a multifactorial gait disorder and problems related to a weakness gait disorder. Some sample multifactorial gait disorder diagnoses that you will find in the ICD-10 lexicon include:

• R26.2: difficulty in walking;
• R29.6: falling;
• R26.81: unsteadiness on feet;
• R26.89: other abnormalities of gait and mobility; and
• R26.9: unspecified abnormalities of gait and mobility.

Each of these diagnoses comes with its own set of quirks and rules—including R codes for abnormal clinical and laboratory findings—so be sure to read up on the codes before applying them. And when looking at a patient with a weakness gait disorder or muscle weakness, try looking at another ICD-10 cm diagnosis code.

Will my claim be denied if I use Z74.09?  

Because Z74.09 is so broad—and it’s a Z code—there is the risk of a claim denial if what you're coding for does not match the supporting documentation and there appears to be a more specific condition. Like many other billing issues, your fortunes may depend upon the payer you’re dealing with and your documentation’s ability to substantiate your coding.  

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Unfortunately, insurance rules are convoluted and don’t always adhere to best practices—nor do they provide much transparency. The best course of action is to call the specific insurance payer representative.

What about gait and mobility disorders in patients with COVID-19?

According to CMS, If you’re treating patients who have contracted COVID and are dealing with impaired mobility as a result of that, you would use U09.9 as a secondary code along with the code for the specific condition related to COVID. We should note that this code is to be used for post-COVID conditions and not for conditions associated with an ongoing COVID-19 infection. For a current COVID infection, you would use code U07.1, and instances of a current COVID infection along with symptoms from a prior infection would require both U09.9 and U07.1.   

What are good resources for rehab therapists to find ICD-10 codes?

John Wallace, PT, MS, OCS, Chief Compliance Officer at WebPT has noted the continued difficulty rehab therapists have when correctly coding ICD-10. He recommends rehab therapists use their current EMR’s tools to search for the appropriate diagnosis, or—if necessary—look to outside assistance in the form of the free database ICD10data where over 69,000 codes can be searched. Looking for a specific code that is elsewhere classified with a similar diagnosis can help you code for the most applicable code for your patient.

How can enabling machines help with ICD-10 codes?

Aside from knowing how to assign the correct ICD-10 code to each patient’s case, there are many automated workflows that the best EMRs have built into their software. Technology can also assist in accurately coding for specific developmental disorders and issues related to motor function. For example, WebPT uses an intuitive, purpose-built Practice Experience Management platform for rehab therapists that eliminates extra clicks and helps you select the correct ICD-10-CM code. After all, shouldn’t the software you use be a partner in delivering care and creating the ideal practice experience?