Warren Hegg doubled up with a recurrence of the back spasm which he first suffered during the game against Notts last month, Wasim Akram's hopes of playing today took a fresh blow when he again felt a reaction to his shoulder problem, and pacemen Peter Martin and Richard Green were prevented from bowling by back and ankle injuries respectively.
So as well as Ridgway, Lancashire called up wicket keeper Jamie Haynes and all-rounder Darren Shadford - who share a grand total of three Championship appearances between them.
Even coach Dav Whatmore suffered an injury - a nasty split thumb while he was taking slip catching practice.
Ridgway, born in Yorkshire and educated in Settle, joined Lancashire in 1995 and has been a virtual ever-present for the second team for the past two seasons. The seconds were already in deep trouble against Gloucester after being bowled out for 45, one of their lowest-ever totals, in the first innings yesterday.
Gary Yates claimed five wickets on a turning pitch to reduce Gloucester to 113-7 in reply, but Peter Sleep's table-topping side still faced a massive battle to avoid their first defeat of the season.
But there was good news for rookie leg-spinner Chris Schofield, who has been picked for England under-19s.
There will be a strong Lancashire influence on the squad, with Andrew Flintoff captain and John Abrahams coach.
Selection continues an amazing few months for Schofield, who until the start of this season was just a promising opening batsman and leg-spinner with Littleborough.
Then he was invited for trials with Lancashire, quickly offered a contract, and almost immediately asked to join England in their Ashes preparations to help counter the threat of Shane Warne.