Prutton passed that mark during the 2-0 win over Swindon Town at the weekend and United today extended his contract until the end of next season.
The former Nottingham Forest trainee has made 18 outings in all this season, scoring twice, in United's League One victories over Swansea City and Millwall.
But Prutton will miss tomorrow's FA Cup first-round replay with Hereford United after incurring a one-match ban for five bookings.