SANTA CLARA -- Will Tukuafu, waived three months ago with a knee injury, returned to the 49ers on Wednesday to help replace injured fullback Bruce Miller, who was placed on season-ending injured reserve with a scapula injury.
Tukuafu split time last season on the defensive line and at fullback, albeit in a limited role on short-yardage and goal-line situations. He missed most of the 2011 season with a wrist injury, and he was on the practice squad most of his 2010 rookie season.
Miller fractured his left scapula in Sunday's 33-14 win at Tampa Bay.
Anthony Dixon is expected to get first crack at assuming Miller's role, which expanded this season as both Frank Gore's lead blocker and a viable passing target for Colin Kaepernick.
Regarding Dixon, Kaepernick said Wednesday: "He's someone who has no fear running through holes, taking on linebackers. He kind of lives for that type of thing. ... To see him in there as a full-time guy or however they end up working it out, it'll be interesting to see how he plays game day."
The 49ers brought in Owen Marecic on Monday but he opted not to re-sign with the club, this newspaper reported earlier Wednesday.
Also capable of picking up some of the offensive slack will be tight end Derek Carrier, whose won over Kaepernick and coaches since his promotion from the practice squad five games ago.
Kaepernick said of Carrier: "I don't want to compare him to Vernon (Davis) because he doesn't have that freakish speed. But as far as being that receiving tight end, he has a wiggle to him. He can get open, he can get separation. And I think we like him the more and more he's on the field. And he's someone who could play a role moving forward depending on how things work out."