Kyle Mills is contemplating a summer on the sidelines.

The Black Caps seamer will have knee surgery on Friday and a shoulder operation a week later, putting him out of action for at least four months.

Mills says he has been battling patella tendonitis for the last two years.

"And then I did my shoulder at the start of the year in the T20 World Cup up in England, I've tried to play through that but that's just really got to the stage where it's really affecting my bowling. It's just an opportunity to get both of them done at the same time."

The 30-year-old concedes his age may be a factor in his injuries.

"Once I did hit 30 these sort of things became a bit more frequent, a bit more painful actually. So I think that's probably telling me something within itself."

Mills is targeting to return to cricket in March and be back playing for the Black Caps for the World Twenty20 tournament in the Caribbean in late April.