Ulster have suffered a setback after recent back-row signing Tim Boys was ruled out for the rest of the season because of a tendon injury to a toe.
Boys injured the toe on his left foot in training last week. He underwent surgery on Wednesday and will be out for the remainder of the PRO12 campaign.
"It is disappointing for both the province and the individual when a player is brought in as cover and sustains an injury that sidelines him for the duration of his short term contract," said Ulster team manager Bryn Cunningham.
"It is particularly frustrating for all involved when they get through the initial bedding in period, become accustomed to the squad and the calling structures and are ready to integrate into the Matchday 23, only to get injured that week.
"For this to happen to both Ronald Raaymakers, earlier in the season, and now Tim is exceptionally unfortunate."