Subsequent investigation has diagnosed a lateral collateral ligament tear, and the player is expected to be unavailable for selection for up to eight weeks.
Tight-head prop Kalman reported a back complaint in the aftermath of the recent friendly against Sale Sharks.
The 30-year-old has since undergone surgery on his back, and is expected to be unavailable for selection for at least three months.
Hooker MacArthur, meanwhile, has been diagnosed with a fractured foot after coming off prematurely in the Scarlets match. The injury requires surgery, and the player is expected to be unavailable for selection for at least three to four months.
63x46.png){kind=logo}