Knee replacement clinicians in Berkeley, California
CMS lists 15 clinicians with a primary specialty of Orthopedic Surgery, Sports Medicine, or Hand Surgery who have billed Medicare for at least one knee replacement and practice in Berkeley, California (details below).
Knee replacement volume
| Clinician | Knee replacements billed | Percentile rank |
|---|---|---|
| Sean Griffiths, DO | 137 | 96% |
| Erik Hansen, MD | 97 | 91% |
| Basil Alwattar, MD | 73 | 85% |
| Christopher Chen, MD | 72 | 84% |
| Alexander Bradley, MD | 71 | 84% |
| Stefano Bini, MD | 55 | 77% |
| Thomas Barber, MD | 38 | 66% |
| Claudio Diaz Ledezma, MD | 24 | 52% |
| Brad Zwahlen, MD | 16 | 41% |
| Robert Eppley, MD | 15 | 39% |
| Amir Jamali, MD | 15 | 39% |
| Jeffrey Mann, MD | 12 | 33% |
| Virginia Lieu, MD | 1-10 | 31% or below |
| Adam Warren, MD | 1-10 | 31% or below |
| Steven Zourabian, DO | 1-10 | 31% or below |
Sorted by the number of knee replacements billed to Medicare, highest first, not by quality or skill. CMS suppresses counts between 1 and 10 to protect patient privacy and publishes the range instead.
Understanding CMS Data
CMS's "Knee replacement" category combines specific billing codes for knee replacement surgery to calculate the number of times each clinician billed Medicare for a "Knee replacement." These include first-time knee replacement, partial knee replacement, and revision of a previous knee replacement. CMS reports only procedures that clinicians billed to Original Medicare and Medicare Advantage. Therefore, CMS's procedure volume data does not include procedures that clinicians may have performed on patients who have other health care coverage (e.g., commercial insurance, self-pay, or the VA). Billing variation and coding errors can also affect CMS's data. Therefore, the number of procedures that CMS reports for a clinician may be higher or lower than the actual number of knee replacements a clinician performed during the reporting period. Lastly, only clinicians with a primary specialty of Orthopedic Surgery, Sports Medicine, or Hand Surgery (as reported to Medicare) are presented.
Source: Centers for Medicare & Medicaid Services (August 18, 2026 release).