Leonard Onsen
Leonard Onsen is a Sports Medicine (Orthopaedic Surgery) Physician in Los Angeles, CA, registered under NPI 1104321421. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 6801 PARK TER STE 400, Los Angeles, CA 90045. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| A185557 | CA | Sports Medicine (Orthopaedic Surgery)… primary |
| 036171278 | IL | Sports Medicine (Orthopaedic Surgery)… |
| 036171278 | IL | Orthopaedic Surgery Physician |
Licences are recorded in 2 states: CA, IL. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
- Status
- Approved
- Provider type
- Practitioner - Sports Medicine
- PAC ID
- 0648528497
Medicare enrolment is recorded as approved under the provider type Practitioner - Sports Medicine. This means the provider is enrolled to bill Medicare, though it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
Licensed in 2 states
This provider holds licences in 2 states: California and Illinois. The practice address on file is in Los Angeles, CA, but a licence in another state usually means they see patients there too — either at a second location or by telehealth. If the address above is far from you, it is worth calling to ask whether they practise closer to where you live.
- Licence
- A185557
- Specialty
- Sports Medicine (Orthopaedic Surgery)…
- Licence
- 036171278
- Specialty
- Sports Medicine (Orthopaedic Surgery)…
Licence numbers are self-reported to NPPES at registration. They do not confirm a licence is currently active, in good standing, or valid for the specialty shown — only the state board can tell you that, which is why we link to each one.
What Sports Medicine covers
An orthopaedic surgeon trained in sports medicine provides appropriate care for all structures of the musculoskeletal system directly affected by participation in sporting activity. This specialist is proficient in areas including conditioning, training and fitness, athletic performance and the impact of dietary supplements, pharmaceuticals, and nutrition on performance and health, coordination of care within the team setting utilizing other health care professionals, field evaluation and management, soft tissue biomechanics and injury healing and repair. Knowledge and understanding of the principles and techniques of rehabilitation, athletic equipment and orthotic devices enables the specialist to prevent and manage athletic injuries. NUCC Health Care Provider Taxonomy, code 207XX0005X
All registered taxonomy codes
This provider registers 3 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 207XX0005X | Sports Medicine (Orthopaedic Surgery) Physician Sports Medicine | A185557 | CA | primary |
| 207XX0005X | Sports Medicine (Orthopaedic Surgery) Physician Sports Medicine | 036171278 | IL | |
| 207X00000X | Orthopaedic Surgery Physician | 036171278 | IL |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1104321421 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Mar 28, 2018 |
| Last updated | Nov 17, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Practice address |
6801 PARK TER STE 400 Los Angeles, CA 90045 (310) 665-7200 |
| Mailing address |
370 W OAK ST Coal City, IL 60416 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 1 | 0 | 4 | 3 | 2 | 1 | 4 | 2 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 1 | 0 | 4 | 6 | 2 | 2 | 4 | 4 |
Sum = 49 · next multiple of 10 = 50 · check digit = 1 · actual last digit = 1
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.