Quick answers
- Which hospitals does Leonard T. Onsen work at?
- Medicare's official clinician data lists Leonard T. Onsen at 3 hospitals: OSF Saint Clare Medical Center, OSF Saint Elizabeth MDL Center and OSF Saint Paul Medical Center. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Leonard T. Onsen see patients?
- Medicare's clinician data lists 1 practice location in Ottawa, IL. Call before your visit to confirm the address.
- What is Leonard T. Onsen's specialty?
- Medicare lists Sports Medicine as the primary specialty, and also Orthopedic Surgery.
- Does Leonard T. Onsen accept Medicare assignment?
- Yes. Medicare's clinician data says Leonard T. Onsen accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Leonard T. Onsen?
- (815) 431-5746, as listed in official Medicare / NPI Registry data.
- What is Leonard T. Onsen's NPI number?
- 1104321421. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Leonard T. Onsen works
Medicare's Facility Affiliation Data lists Leonard T. Onsen at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- OSF Saint Clare Medical CenterPrinceton, IL · Critical Access Hospital · CCN 141337
- OSF Saint Elizabeth MDL CenterPeru, IL · Acute Care Hospital · CCN 140110
- OSF Saint Paul Medical CenterMendota, IL · Critical Access Hospital · CCN 141310
Practice locations
Addresses where Leonard T. Onsen is enrolled with Medicare (CMS data updated 2026-10-02).
- 1050 E Norris Dr, Suite 3a OrthoOttawa, IL 61350 (815) 431‑5746
Group practices
Medicare enrollment lists Leonard T. Onsen as a member of this group (CMS data updated 2026-10-02).
- OSF Multi-Specialty Group2,114 clinicians in the group
Specialties
- Sports Medicineprimary
- Orthopedic Surgeryalso
Other sports medicine doctors in Illinois
Clinicians with the same Medicare primary specialty in Illinois — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2018 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1104321421 |
| 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
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- 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