It came as a shock when Cam Newton suddenly had surgery on his ankle last week.

Now it's beginning to make sense. Panthers coach Ron Rivera told reporters that Newton has dealt with an ankle injury since his college days. Every offseason Newton would receive treatment on it. But this time, it wasn't healing properly.

"Every year rest, treatment was part of the rehab program," Rivera said, via ESPN.com. "This year they went through the program, and when he started working out it just wasn't feeling right, so he went and saw the doctor."

Newton is not expected to participate in offseason football activities as his ankle heals. He should be ready for the start of the 2014 season.

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Aaron Wilson covers the Ravens for The Baltimore Sun.