French Federation doctor Bernard Montalvan said Monfils contracted Osgood-Schlatter's disease when he was a teenager.
The illness, according to Montalvan
, can cause acute inflammation in the knee that Monfils has been experiencing.
"From time to time, there is an inflammation of the kneecap tendon and it's the case now," Montalvan
told L'Equipe in an interview last month.