Surgery isn't a solution if he wants to continue playing tennis.His foot condition is something of congenital issue and started to have pain as early as the age of 7, AFAIK.
the pain grew to an unbearable one at 17 and had to take a few months off.
A lot knee pains were supposed to have been induced by his foot where he corrected via an aggressive orthotics.
But his uncle mentioned it became more and more difficult to play on grass over the years.
So I'm afraid there might be some condition in his left foot have gotten worse over the years.
And maybe only solution now is a surgery, no?