The Ospreys hooker, who last year was bizarrely sidelined after being bitten on the hand by a lion, was hurt in training and requires surgery that will keep him out of action for five months.
A Wales Rugby Union statement confirmed that Scarlets' Ryan Elias, who has two international caps, has been called up in his place.
Wales are already shorn of several players, with the likes of Sam Warburton, Taulupe Faletau, Dan Lydiate, Rhys Webb, Jonathan Davies, Liam Williams, Dan Biggar and Rhys Priestland among their absentees.
Warren Gatland's side start their Six Nations campaign against Scotland in Cardiff on Saturday.
TEAM NEWS Wales name team for @SixNationsRugby opener against @Scotlandteam , with @JoshAdams951 set for debut. Gêm enfawr yn @principalitysta !https://t.co/PnCmyDtWAa #WALvSCO pic.twitter.com/LWVDnL3tdE
— Welsh Rugby Union (@WelshRugbyUnion) January 30, 2018