Quick answers
- Does Gregg P. Hartman accept Medicare assignment?
- Yes. Medicare's clinician data says Gregg P. Hartman accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Gregg P. Hartman see?
- In 2024, CMS data shows 700 Original Medicare patients and 11,868 services for Gregg P. Hartman. This counts Original Medicare only and measures volume, not quality.
- What is Gregg P. Hartman's NPI number?
- 1336105238. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Gregg P. Hartman, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 700 |
|---|---|
| Services billed to Medicare | 11,868 |
| Different services or procedures | 82 |
| Participating Medicare provider | Yes |
| Average age of these patients | 75 |
Most frequent services
- Hyaluronan or derivative, durolane, for intra-articular injection, 1 mg (J7318)5,580 services
- Injection, triamcinolone acetonide, preservative-free, extended-release, microsphere formulation, 1 mg (J3304)2,080 services
- Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)454 services
- Injection, betamethasone acetate 3 mg and betamethasone sodium phosphate 3 mg (J0702)444 services
- Injection, gadolinium-based magnetic resonance contrast agent, not otherwise specified (nos), per ml (A9579)349 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High cholesterol75%
- Arthritis75%
- High blood pressure71%
- Ischemic heart disease29%
- Diabetes25%
- Depression22%
Practice locations
Addresses where Gregg P. Hartman is enrolled with Medicare (CMS data updated October 2, 2026).
- 137 E Thousand Oaks BlvdThousand Oaks, CA 91360 (805) 379‑4574
- 2525 Erringer RdSimi Valley, CA 93065 (805) 527‑1404
Group practices
Medicare enrollment lists Gregg P. Hartman as a member of this group (CMS data updated October 2, 2026).
- Ventura Orthopedics Medical Group Inc72 clinicians in the group
Specialties
- Sports Medicineprimary
- Orthopedic Surgeryalso
Other sports medicine doctors in California
Clinicians with the same Medicare primary specialty in California — not a recommendation.
Other clinicians in Ventura Orthopedics Medical Group Inc
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Tulane University School Of Medicine |
| Graduation year | 1992 (34 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1336105238 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians