Chapter 9, section H.14, of the National Correct Coding Initiative Policy Manual states, "Although it may be medically reasonable and necessary to report both axial and peripheral bone density studies on the same date of service, NCCI edits prevent the reporting of multiple CPT codes for the axial bone density study or multiple CPT codes for the peripheral site bone density study on the same date of service."
Experts indicate this means that you should be able to append modifier 59 (Distinct procedural service) to override the edit when you meet the "reasonable and necessary" criteria.
Snag: You will need to check your payer's policy on when it considers 77080 and 77081 performed on the same date to be reasonable and necessary.
For example, WPS Medicare states, "Medicare will not reimburse for both axial and appendicular testing on the same date of service or within 30 days of each other, unless the medical records substantiate that the BMM initially obtained was unreadable. Conditions that verify to Medicare that a BMM is unreadable and a second BMM is medically necessary include documentation the patient has artificial instrumentation in place in either hip or spine, or other conditions that preclude a reading in those locations"