Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Mr. Gregory Roger Grenier, DO

Individual provider Orthopaedic Surgery Physician · NPI 1134512593

Mr. Gregory Roger Grenier, DO practises Orthopedic Surgery in Billings, Montana. Qualified in 2015, 11 years ago. Practices with Catholic Health Initiatives Colorado, a 1,266-clinician group, works from 2 locations and accepts Medicare assignment. Licensed in Colorado and Montana.

Years since qualifying
11
Licensed in
CO, MT
In the registry since
2015
Specialties on file
2
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

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Practice location Address checks out

2900 12th Ave N Ste 140W
Billings, MT 59101-7507
Phone: (406) 238-6726
Fax: (406) 272-3395
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Additional practice locations (1)

  • 1 Mercado St Ste 202, Durango, CO 81301-7307 — (970) 764-9400

Specialties & licences

Orthopaedic Surgery Physician (primary) Taxonomy 207X00000X · Licence 98833 (MT)
Orthopaedic Surgery Physician Taxonomy 207X00000X · Licence DR.0070117 (CO)

Record details

NPI number1134512593
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedMarch 10, 2015
Last updated in NPPESJanuary 6, 2023
Certification dateJanuary 6, 2023

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyORTHOPEDIC SURGERY
Medical schoolOTHER
Graduated 2015 (11 years in practice)
Group practice Catholic Health Initiatives Colorado — 1266 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Lower limb (leg) arthroscopy (minimally invasive joint repair) 1–10 times
Melanoma (skin cancer) excision 1–10 times
Removal of tissue 1–10 times
Upper limb (arm) arthroscopy (minimally invasive joint repair) 1–10 times

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients177
Services billed 859 a service is one billed item, such as a visit, a test or a procedure
Average patient age74

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Food and Beverage $197 6 payments · a meal or drink at a meeting or visit, not a fee

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at Catholic Health Initiatives Colorado

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 1266 clinicians in the practice; 12 are shown here.

Other providers in Billings