Johnson, the first overall pick of the 2006 draft, is expected to be ready for training camp next season. He tore two ligaments when his foot got stuck in a golf cart.
The surgery was performed Wednesday by Dr. Mike Stuart at the Rochester Mayo Clinic in Minnesota. The second of the torn ligaments has healed on its own, and according a report in the St. Louis Post-Dispatch, no further damage was found during the procedure.
"Dr. Stuart was happy with it," Johnson said in the Post-Dispatch. "He said everything went great and I should have 100 percent recovery. I'm glad it's out of the way and I can focus on my rehab, gearing up toward next season and making sure my knee is strong and fit."
Information from The Associated Press was used in this report.