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

Dr. John Nicholas Harker, DO

Individual provider Orthopaedic Surgery Physician · NPI 1013026269

Dr. John Nicholas Harker, DO practises Orthopedic Surgery in Largo, Florida. Graduated from Nova Southeastern College of Osteo Medicine in 1989, 37 years ago. Practices with Paul J Wisniewski DO Inc, a 19-clinician group, works from 2 locations and accepts Medicare assignment. Licensed in California and Florida.

Years since qualifying
37
Trained at
Nova Southeastern College of Osteo Medicine
Licensed in
CA, FL
In the registry since
2006
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

12955 Seminole Blvd
Largo, FL 33778-2399
Phone: (727) 586-4752
Show map & directions

Directions in Google Maps · Apple Maps · OpenStreetMap

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Additional practice locations (1)

  • 18523 Corwin Rd Ste A, Apple Valley, CA 92307-2300 — (909) 712-2764

Specialties & licences

Orthopaedic Surgery Physician (primary) Taxonomy 207X00000X · Licence OS-0006819 (FL)
Orthopaedic Surgery Physician Taxonomy 207X00000X · Licence 20A23999 (CA)

Record details

NPI number1013026269
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorYes
NPI enumeratedAugust 30, 2006
Last updated in NPPESSeptember 12, 2025
Certification dateSeptember 12, 2025

Medicare enrollment

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

Medicare specialtyORTHOPEDIC SURGERY
Medical schoolNOVA SOUTHEASTERN COLLEGE OF OSTEO MEDICINE
Graduated 1989 (37 years in practice)
Group practice Paul J Wisniewski Do Inc — 19 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations3 on file with Medicare

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.

Knee replacement 1–10 times
Lower limb (leg) arthroscopy (minimally invasive joint repair) 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 610 a service is one billed item, such as a visit, a test or a procedure
Average patient age77

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 $3,264 54 payments · a meal or drink at a meeting or visit, not a fee
Travel and Lodging $2,317 4 payments · travel or lodging paid or reimbursed, such as to attend a conference
Long term medical supply or device loan $536 2 payments · a device or supply lent for a long period, not cash
Education $73 1 payment · educational material or training, 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. Those with a page here are linked.

  • Providence St Mary Medical Center Hospital · Apple Valley, CA · listed as St Mary Medical Center
  • Hca Florida Largo Hospital Hospital · Largo, FL
  • Enhabit Home Health Home health agency · Clearwater, FL

Colleagues at Paul J Wisniewski DO Inc

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 19 clinicians in the practice; 12 are shown here.

Other providers in Largo