Just because a code is billable, doesn't make it the best possible code for a therapy diagnosis. I have certificates in billing and coding and constantly come across codes, such as 719.7, which is difficulty in walking. This can be the "catch-all" code for almost any therapy patient we see in the clinics. The same with 781.92 (abnormal posture) and 781.2 (abnormality of gait).
Perhaps 729.89 (other musculoskeletal symptoms referable to limbs) could be used because it's just as vague as the other therapy diagnoses. What I'd like to see is a separate and clearer therapy diagnosis that would better reflect why the patient is being seen for therapy.
I've come across codes like 596.0 (unspecified disorder of bladder) as the main therapy diagnosis. My first question is why would an insurance company pay for therapy services on a patient with a bladder infection? It doesn't make sense, but then again I'm not a PT who decides the diagnosis of the patients, am I? If I was the insurance carrier, I wouldn't pay for any rehab services when the best therapy diagnosis to justify treatment is a bladder infection.
If the PT isn't sure what the best diagnosis is for the patient, he should ask. Based on the evaluation, there could be several, more specific diagnoses to better justify therapy services. Some clinics may have a coder who can accurately code the patient with the best diagnosis and possibly receive a higher reimbursement rate because the patient is coded correctly. I'm sure there are many MD health clinics that hire coders specifically for that reason. With direct access, it seems that providers would want to ensure all codes are specific to the patient's condition and not some vague weakness code that seems so prevalent in the clinic today, like 780.79 (other malaise and fatigue).