Coding for Impairment Rating
I am doing similar analysis. There are a couple of options based on what is being done and how impairment is being calculated.
If a history and physical examination of the patient is being performed by a physician, and the physician is using exam data (ROM method) or imaging data (DRE method)to calculate impairment then 99455/99456 would be appropriate.
A more interesting scenario is when a physician is using imaging data alone to calculate impairment using the DRE method (AMA 5th edition). The choice is either to consider that calculation of permanent impairment is in essence an analysis of a patient's capacity for physical performance (therefore possibly 97750) or is in effect the professional component of the imaging studies evaluated. While you normally would not report the professional component of an imaging study more than once (by different providers), there is some persuasive authority that suggests this is appropriate where the analysis leads to a substantively different conclusion.
I note that some commercial carriers will only pay the global service - once. They then leave it to the parties performing the respective professional and technical components of the test to do the split among themselves. In such a situation, the physician doing the DRE impairment analysis could not get paid under this billing approach.
To successfully argue in favor of 97750 would be difficult. This code is generally described as relating to the computerized analysis of muscle strength and ROM although there are any number of other physical demand tests that can be included as might be the case with an FCE. 97750, however, does not have a professional/technical component. Despite the report requirement, which simply must detail the results of the test, it is purely technical. Since the DRE analysis of images is purely a professional component analysis, it is not clear that 97750 is appropriate. Even where muscle testing/ROM is performed, 97750 is for reporting the physical capture of the data. If any interpretation is performed by a physician on the same date, then it would seem an E/M service is appropriate if an established patient because now, we have 2 of the 3 key components of an E/M (exam, decision-making) necessary to report an established patient E/M. If performed by a PT/OT, consider that as soon as analysis is performed, the services likely becomes a PT/OT eval/re-eval.
Hopefully this gives you some thoughts as you resolve this issue. As always, check any binding guidance from the carrier on this issue before making a decision and recognize that this guidance could potentially change from one carrier to the next.